View source for Thomas Aquinas

{{Short description|Italian Dominican theologian and philosopher (1225–1274)}}
{{redirect|Aquinas|the ship that sank in 2013|MV St. Thomas Aquinas{{!}}MV ''St. Thomas Aquinas''|other uses}}
{{Medieval Italian name|Aquinas|Thomas}} 
{{Use dmy dates|date=February 2023}}
{{Infobox saint
|honorific-prefix = [[Saint#Catholic Church|Saint]]
|name= Thomas Aquinas
|honorific-suffix= [[Order of Preachers|OP]]
|image=St-thomas-aquinasFXD.jpg
|caption=Panel of an altarpiece from [[Ascoli Piceno]], Italy, by [[Carlo Crivelli]] (15th century)
|major_shrine=[[Church of the Jacobins]], [[Toulouse]], France
|titles= [[Confessor]]<br />[[Doctor of the Church]]
|birth_name = Tommaso d'Aquino
|birth_date = 1225
|birth_place = [[Roccasecca]], [[Kingdom of Sicily]]
|death_date = 7 March {{death year and age|1274|1225}}
|death_place = [[Fossanova Abbey|Fossanova]], [[Papal States]]
|beatified_date=
|beatified_place=
|beatified_by=
|canonized_date= 18 July 1323
|canonized_place=[[Avignon]], [[Papal States]]
|canonized_by= [[Pope John XXII]]
|feast_day= 28 January, 7 March (pre-1969 Roman calendar/traditional Dominican calendar)
|venerated_in=[[Catholic Church]]<br />[[Anglican Communion]]<ref name=diobeth /><br />[[Lutheranism]]<ref name=resurrectionpeople.org />
|attributes=The ''[[Summa Theologica|Summa Theologiae]]'', a model church, the sun on the chest of a [[Dominican Order|Dominican]] [[friar]]
|patronage=Academics; against storms; against lightning; apologists; Aquino, Italy; [[Belcastro, Italy]]; booksellers; Catholic academies, schools, and universities; chastity; Falena, Italy; learning; pencil makers; philosophers; Saint Philip Neri Seminary; publishers; scholars; students; [[University of Santo Tomas]]; [[Santo Tomas, Batangas|Sto. Tomas, Batangas]]; [[Mangaldan, Pangasinan]]; theologians<ref name=catholicsaints.info />
|module = {{Infobox philosopher
|embed=yes
|region = [[Western philosophy]]
|era = [[Medieval philosophy]]
|name = Thomas Aquinas
|other_names = ''Doctor Angelicus'' (the Angelic Doctor)
|education = [[Abbey of Monte Cassino]]<br />[[University of Naples Federico II|University of Naples]]<br />[[University of Paris]]
|notable_works = {{Unbulleted list|''[[Summa Theologica|Summa Theologiae]]''|''[[Summa contra Gentiles]]''}}
|school_tradition = [[Scholasticism]]<br />[[Thomism]]<br />[[Aristotelianism]]<br />[[Medieval theological intellectualism|Theological intellectualism]]<br />[[Moderate realism]]<ref>{{cite book |last=Maritain |first=Jacques |author-link=Jacques Maritain |translator-last=Watkin |translator-first=E. I. |translator-link= E. I. Watkin |year=2005 |title=An Introduction to Philosophy |url=https://books.google.com/books?id=A60EaqmQ9-EC |location=[[Lanham, Maryland]] |publisher=[[Rowman & Littlefield|Rowman & Littlefield Publishers, Inc.]] |page=112 |isbn=9781461667377}}</ref><br />[[Virtue ethics]]<br />[[Natural law]]<br />[[Correspondence theory of truth]]<ref name="SEP" />
|main_interests =
{{flatlist|
* [[Metaphysics]]
* [[Logic]]
* [[Catholic theology|Theology]]
* [[philosophy of mind|Mind]]
* [[Epistemology]]
* [[Ethics]]
* [[political philosophy|Politics]]
* [[Aristotelian theology]]
}}
|notable_ideas = {{plainlist|
* [[Natural law]]
* [[Five Ways (Aquinas)|Five proofs of God's existence]]
* ''[[Analogia entis]]''
* [[Hylomorphism#Thomistic hylomorphism|Thomistic hylomorphism]]
* [[Divine simplicity]]
* [[Peripatetic axiom]]
* [[Principle of double effect]]
* ''[[Homo unius libri]]''
* [[Infused righteousness]]
* [[Medieval theological intellectualism|Theological intellectualism]]
* [[Quiddity]]
* [[Just price]]
* ''[[Determinatio]]''
* ''[[Actus purus]]''
* ''[[Actus essendi]]''
* [[Thomistic sacramental theology]]
}}
}}
}}

'''Thomas Aquinas''' {{post-nominals|post-noms=[[Dominican Order|OP]]}} ({{IPAc-en|ə|ˈ|k|w|aɪ|n|ə|s|audio=En-us-Aquinas.oga}} {{respell|ə|KWY|nəs}}; {{langx|it|Tommaso d'Aquino|lit=Thomas of [[Aquino, Italy|Aquino]]}}; {{circa|1225}} – 7 March 1274) was an Italian{{sfnm |1a1=Conway |1y=1911 |1p= |2a1=Vaughan |2y=1871 |2p=}} [[Dominican Order|Dominican]] [[friar]] and [[Catholic priest|priest]], the foremost [[Scholasticism|Scholastic]] thinker,<ref>{{cite encyclopedia |title=Thomas Aquinas |encyclopedia= Encyclopedia Britannica|date= |year= |last= |first= |publisher= |location= |id= |url= https://www.britannica.com/biography/Saint-Thomas-Aquinas|access-date=October 9, 2024 |quote= Thomas Aquinas... was an Italian Dominican theologian, the foremost medieval Scholastic.}}</ref> as well as one of the most influential philosophers and theologians in the Western tradition.<ref>{{cite encyclopedia |year= |title=Thomas Aquinas (1224/6–1274) |encyclopedia=Internet Encyclopedia of Philosophy |publisher= |location= |id= |url=https://iep.utm.edu/thomas-aquinas/ |access-date=October 10, 2024 |last= |first= |date= |quote=However, it also seems right to say—if only from the sheer influence of his work on countless philosophers and intellectuals in every century since the 13th, as well as on persons in countries as culturally diverse as Argentina, Canada, England, France, Germany, India, Italy, Japan, Poland, Spain, and the United States—that, globally, Thomas is one of the 10 most influential philosophers in the Western philosophical tradition.}}</ref> He was from the county of [[Aquino, Italy|Aquino]] in the [[Kingdom of Sicily]].

Thomas was a proponent of [[natural theology]] and the father of a school of thought (encompassing both theology and philosophy) known as [[Thomism]]. Central to his thought was the doctrine of [[natural law]], which he argued was accessible to [[Reason|human reason]] and grounded in the very nature of human beings, providing a basis for understanding [[individual rights]] and [[Moral duty|moral duties]].<ref>{{cite book |last=Finnis |first=John |title=Aquinas: Moral, Political, and Legal Theory |publisher=Oxford University Press |year=1998 |isbn=978-0198780854}}</ref> He argued that God is the source of the light of natural reason and the light of faith.<ref>{{Cite web |url=https://isidore.co/aquinas/english/BoethiusDeTr.htm#23 |title=Thomas Aquinas, Commentary on the De Trinitate of Boethius, quest. 2, art. 3 |access-date=22 February 2021 |archive-date=18 September 2021 |archive-url=https://web.archive.org/web/20210918062212/https://isidore.co/aquinas/english/BoethiusDeTr.htm#23 |url-status=live }}</ref> He embraced<ref name="SEP3" /> several ideas put forward by [[Aristotle]] and attempted to synthesize [[Aristotelianism|Aristotelian philosophy]] with the principles of Christianity.<ref>{{cite web |url= http://www.dartmouthapologia.org/articles/show/125 |title=Reason and Faith: The Thought of Thomas Aquinas |last=Blair |first= Peter |website=The Dartmouth Apologia |url-status=dead |archive-url= https://web.archive.org/web/20130913011656/http://www.dartmouthapologia.org/articles/show/125 |archive-date=13 September 2013 |access-date=18 December 2013}}</ref> Aquinas' natural law theory has been influential in shaping ideas about [[Liberty|human liberty]] and the [[Limited government|moral limits of government authority]].<ref>{{cite book |last=McInerny |first=Ralph |title=Aquinas on Human Action: A Theory of Practice |publisher=Catholic University of America Press |year=1992 |isbn=978-0813207612}}</ref><ref>{{cite book |last=Schall |first=James V. |title=Thomas Aquinas: Scholar, Theologian, and Political Thinker |publisher=Rowman & Littlefield Publishers |year=1996 |isbn=978-0847681903}}</ref> He has been described as "the most influential thinker of the [[medieval period]]"<ref>[[John F. Wippel|Wippel, John F.]] (1995) 2nd ed., "Aquinas, Saint Thomas", ''[[The Cambridge Dictionary of Philosophy]]'', Cambridge University Press. p. 36.</ref> and "the greatest of the [[medieval philosophy|medieval philosopher]]-theologians".<ref>[[Alexander Broadie|Broadie, Alexander]] (1999). "Aquinas, St Thomas", ''[[The Oxford Companion to Philosophy]]'', Oxford University Press, p. 43.</ref> 

Thomas's best-known works are the unfinished ''[[Summa Theologica]]'', or ''Summa Theologiae''<!-- Keep both titles here as both titles are used throughout both the body text and the references. If one title is chosen to be used throughout the body text, don't change the ones in the references and therefore still keep both terms here. The citations need to match the titles or quoted text of the reference's source. --> (1265–1274), the ''[[Quaestiones Disputatae de Veritate|Disputed Questions on Truth]]'' (1256–1259) and the ''[[Summa contra Gentiles]]'' (1259–1265). His commentaries on [[Bible|Christian Scripture]] and on Aristotle also form an important part of his body of work. He is also notable for his [[Eucharist]]ic hymns, which form a part of the Church's liturgy.<ref>{{cite web |url=https://www.britannica.com/biography/Saint-Thomas-Aquinas |title=St. Thomas Aquinas {{!}} Biography, Philosophy, & Facts |website=Encyclopædia Britannica  |access-date=20 January 2020}}</ref>

As a [[Doctor of the Church]], Thomas Aquinas is considered one of the Catholic Church's greatest theologians and philosophers.<ref>{{Cite book |title=Selected Philosophical Writings |last=Aquinas |first=Thomas |year=1993 |publisher=Oxford University Press |isbn=0-19-283585-8 |pages=Xi}}</ref> He is known in Catholic theology as the {{lang|la|Doctor Angelicus}} ("Angelic Doctor", with the title "doctor" meaning "teacher"), and the {{lang|la|Doctor Communis}} ("Universal Doctor").{{efn|name=Pius XI}} In 1999, [[John Paul II]] added a new title to these traditional ones: {{lang|la|Doctor Humanitatis}} ("Doctor of Humanity/Humaneness").<ref>{{Cite web |title=Inter Munera Academiarum (January 28, 1999) &#124; John Paul II |url=https://www.vatican.va/content/john-paul-ii/en/apost_letters/1999/documents/hf_jp-ii_apl_19990128_inter-munera-academiarum.html |website=www.vatican.va}}</ref>

==Biography==

===Early life (1225–1244)===
Thomas Aquinas was most likely born in the family castle of [[Roccasecca]],<ref>{{cite book |last1=Walz |first1=Angelus |title=Saint Thomas Aquinas: A Biographical Study |date=1951 |publisher=Newman Press |page=5 |url=https://archive.org/details/saintthomasaquin0000walz/page/4/mode/2up}}</ref> near [[Aquino, Italy|Aquino]], controlled at that time by the [[Kingdom of Sicily]] (in present-day [[Lazio]], Italy), {{circa|1225}}.<ref>{{Cite web |url=https://www.iep.utm.edu/aquinas/ |title=Internet Encyclopedia of Philosophy August 17, 2019 |access-date=17 August 2019 |archive-date=27 July 2019 |archive-url=https://web.archive.org/web/20190727011537/https://www.iep.utm.edu/aquinas/ |url-status=live }}</ref> He was born to the most powerful branch of the family, and his father, Landulf of Aquino, was a man of means. As a knight in the service of [[Emperor Frederick II]], Landulf of Aquino held the title ''[[Knight|miles]]''.<ref>Norman Geisler, ''Thomas Aquinas: An Evangelical Appraisal'', Wipf and Stock Publishers, 2003, p. 26.</ref> Thomas's mother, Theodora, belonged to the Rossi branch of the [[Naples|Neapolitan]] Caracciolo family.{{sfn|Torrell|2005|p=3}} Landulf's brother Sinibald was [[abbot]] of [[Monte Cassino]], the oldest [[Order of St. Benedictine|Benedictine]] [[monastery]]. While the rest of the family's sons pursued military careers,{{sfn|Hampden|1848|p=14}} the family intended for Thomas to follow his uncle into the abbacy;{{sfn|Stump|2003|p= 3}} this would have been a normal career path for a younger son of Southern Italian nobility.<ref name="schaff-422">{{Cite encyclopedia |year=1953 |title= Thomas Aquinas |encyclopedia=The New Schaff-Herzog Encyclopedia of Religious Knowledge |publisher=Baker Book House |location= Grand Rapids, Michigan |last=Schaff |first=Philip |volume=126 |pages=422–423 |bibcode=1930Natur.126..951G |doi=10.1038/126951c0 |issue=3190|s2cid= 4140923 |doi-access=free  |issn=0028-0836}}</ref>

At the age of five Thomas began his early education at Monte Cassino, but after the military conflict between [[Frederick II, Holy Roman Emperor|Emperor Frederick II]] and [[Pope Gregory IX]] spilt into the abbey in early 1239, Landulf and Theodora had Thomas enrolled at the ''[[studium generale]]'' ([[University of Naples Federico II|university]]) established by Frederick in [[Naples]].{{sfn|Davies|2004|pp=1–2}} There, his teacher in arithmetic, geometry, astronomy, and music was [[Petrus de Ibernia]].{{sfn|Grabmann|1963|p=2}} It was at this university that Thomas was presumably introduced to [[Aristotle]], [[Averroes]] and [[Maimonides]], all of whom would influence his theological philosophy.{{sfn|Davies|2004|p=2}} During his study at Naples, Thomas also came under the influence of John of St. Julian, a Dominican preacher in Naples, who was part of the active effort by the [[Dominican Order]] to recruit devout followers.{{sfn|Hampden|1848|pp=21–22}}

[[File:Castello di Monte San Giovanni Campano 9.JPG|thumb|The Castle of [[Monte San Giovanni Campano]]]]

At the age of nineteen, Thomas resolved to join the Dominican Order. His change of heart, however, did not please his family.<ref>Collison, Diane, and Kathryn Plant. ''Fifty Major Philosophers''. 2nd ed. New York: [[Routledge]], 2006.</ref> In an attempt to prevent Theodora's interference in Thomas's choice, the Dominicans arranged to move Thomas to Rome, and from Rome, to Paris.{{sfn|Hampden|1848|p=23}} However, while on his journey to Rome, per Theodora's instructions, his brothers seized him as he was drinking from a spring and took him back to his parents at the castle of [[Monte San Giovanni Campano]].{{sfn|Hampden|1848|p=23}}

Thomas was held prisoner for almost one year in the family castles at Monte San Giovanni and Roccasecca in an attempt to prevent him from assuming the Dominican habit and to push him into renouncing his new aspiration.{{sfn|Davies|2004|p=2}} Political concerns prevented the Pope from ordering Thomas's release, which had the effect of extending Thomas's detention.{{sfn|Hampden|1848|p=24}} Thomas passed this time of trial tutoring his sisters and communicating with members of the Dominican Order.{{sfn|Davies|2004|p=2}}

Family members became desperate to dissuade Thomas, who remained determined to join the Dominicans. At one point, two of his brothers resorted to the measure of hiring a prostitute to seduce him, presumably because sexual temptation might dissuade him from a life of celibacy. According to the official records for his canonization, Thomas drove her away wielding a burning log—with which he inscribed a cross onto the wall—and fell into a mystical ecstasy; two angels appeared to him as he slept and said, "Behold, we gird thee by the command of God with the girdle of chastity, which henceforth will never be imperilled. What human strength can not obtain, is now bestowed upon thee as a celestial gift." From then onwards, Thomas was given the grace of perfect chastity by Christ, a girdle he wore till the end of his life. The girdle was given to the ancient monastery of [[Vercelli]] in Piedmont, and is now at [[Chieri]], near [[Turin]].{{sfn|Hampden|1848|p=25}}<ref>{{cite web|last=Marshall|first=Taylor|date=26 January 2011|title=The Miraculous Cord of Saint Thomas Aquinas and the Angelic Warfare|url=https://taylormarshall.com/2011/01/miraculous-cord-of-saint-thomas-aquinas.html|access-date=22 March 2021|website=Taylor Marshall|language=en-US}}</ref>

[[File:Saint Thomas Aquinas Diego Velázquez.jpg|right|thumb|Thomas is girded by angels with a mystical belt of purity after his proof of [[chastity]]. Painting by [[Diego Velázquez]].]]

By 1244, seeing that all her attempts to dissuade Thomas had failed, Theodora sought to save the family's dignity, arranging for Thomas to escape at night through his window. In her mind, a secret escape from detention was less damaging than an open surrender to the Dominicans. Thomas was sent first to Naples and then to Rome to meet [[Johannes von Wildeshausen]], the [[Master General of the Dominican Order]].{{sfn|Hampden|1848|pp=27–28}}

===Paris, Cologne, Albert Magnus, and first Paris regency (1245–1259)===
[[File:Bernardo Daddi - The Virgin Mary with Saints Thomas Aquinas and Paul - 93.PB.16 - J. Paul Getty Museum.jpg|thumb|right|''The Virgin Mary with s. [[Paul of Tarsus|Paul]] and s. Thomas Aquinas'' ([[altarpiece]] portable to [[triptych]], to [[tempera painting|tempera]] on wood, work by [[Bernardo Daddi]], {{Circa|1330|lk=no}}). The Virgin Mary holds in her hand a text that contains the first words of the ''[[Magnificat]]'', while Thomas, author of one of the most important medieval commentaries on the Pauline epistolary, holds one of his works in her hand.]]
{{Christianity sidebar}}

In 1245, Thomas was sent to study at the Faculty of the Arts at the [[University of Paris]], where he most likely met Dominican scholar [[Albertus Magnus]],{{sfn|Healy|2003|p=2}} then the holder of the Chair of Theology at the College of St. James in Paris.{{sfn|Hampden|1848|p=33}} When Albertus was sent by his superiors to teach at the new ''studium generale'' at [[Cologne]], in 1248,{{sfn|Healy|2003|p=2}} Thomas followed him, declining [[Pope Innocent IV]]'s offer to appoint him abbot of Monte Cassino as a Dominican.{{sfn|Stump|2003|p=3}} Albertus then appointed the reluctant Thomas ''magister studentium''.<ref name="schaff-422" /> Because Thomas was quiet and did not speak much, some of his fellow students thought he was slow. But Albertus prophetically exclaimed: "You call him the dumb ox [''bos mutus''], but in his teaching he will one day produce such a bellowing that it will be heard throughout the world".{{sfn|Stump|2003|p=3}}

Thomas taught in Cologne as an apprentice professor (''baccalaureus biblicus''), instructing students on the books of the [[Old Testament]] and writing ''Expositio super Isaiam ad litteram'' (''Literal Commentary on Isaiah''), ''Postilla super Ieremiam'' (''Commentary on Jeremiah''), and ''Postilla super Threnos'' (''Commentary on Lamentations'').{{sfn|Stump|2003|p=xvi}} In 1252, he returned to Paris to study for a master's degree in theology. He lectured on the Bible as an apprentice professor, and upon becoming a ''baccalaureus Sententiarum'' (bachelor of the ''Sentences''){{sfn|Davies|1993|p=5}} he devoted his final three years of study to commenting on [[Peter Lombard]]'s ''[[Sentences]]''. In the first of his four theological syntheses, Thomas composed a massive commentary on the ''Sentences'' entitled ''Scriptum super libros Sententiarium'' (''Commentary on the Sentences''). Aside from his master's writings, he wrote ''De ente et essentia'' (''On Being and Essence'') for his fellow Dominicans in Paris.{{sfn|Stump|2003|p=3}}

In the spring of 1256, Thomas was appointed regent master in theology at Paris and one of his first works upon assuming this office was ''Contra impugnantes Dei cultum et religionem'' (''Against Those Who Assail the Worship of God and Religion''), defending the [[mendicant order]]s, which had come under attack by [[William of Saint-Amour]].<ref>{{Cite book |title=On Evil |url=https://archive.org/details/onevil00aqui |url-access=limited |last1=Aquinas |first1=Thomas |last2=Regan |first2=Richard J. |last3=Davies |first3=Brian |publisher=Oxford University Press US |year=2003 |isbn=0-19-509183-3 |page=[https://archive.org/details/onevil00aqui/page/n23 5]}}</ref> During his tenure from 1256 to 1259, Thomas wrote numerous works, including: ''[[Quaestiones Disputatae de Veritate]]'' (''Disputed Questions on Truth''), a collection of twenty-nine disputed questions on aspects of faith and the human condition{{sfn|Stump|2003|p=4}} prepared for the public university debates he presided over during [[Lent]] and [[Advent]];{{sfn|Davies|2004|pp=3–4}} ''Quaestiones quodlibetales'' (''Quodlibetal Questions''), a collection of his responses to questions ''[[Quodlibeta|de quodlibet]]'' posed to him by the academic audience;{{sfn|Stump|2003|p=4}} and both ''Expositio super librum Boethii De trinitate'' (''Commentary on Boethius's De trinitate'') and ''Expositio super librum Boethii De hebdomadibus'' (''Commentary on Boethius's De hebdomadibus''), commentaries on the works of 6th-century Roman philosopher [[Anicius Manlius Severinus Boethius|Boethius]].{{sfn|Stump|2003|p=xvii}} By the end of his regency, Thomas was working on one of his most famous works, ''[[Summa contra Gentiles]]''.{{sfn|Davies|2004|p=4}}

===Naples, Orvieto, Rome (1259–1268)===
In 1259, Thomas completed his first regency at the ''[[studium generale]]'' and left Paris so that others in his order could gain this teaching experience. He returned to Naples where he was appointed as general preacher by the provincial chapter of 29 September 1260. In September 1261 he was called to [[Orvieto]] as conventual lector, where he was responsible for the pastoral formation of the friars unable to attend a ''studium generale''. In Orvieto, Thomas completed his ''[[Summa contra Gentiles]]'', wrote the ''[[Catena (biblical commentary)|Catena aurea]]'' (''The Golden Chain''),{{sfn|Healy|2003|p=4}} and produced works for [[Pope Urban IV]] such as the liturgy for the newly created [[feast of Corpus Christi]] and the ''[[Contra Errores Graecorum|Contra errores graecorum]]'' (''Against the Errors of the Greeks'').{{sfn|Davies|2004|p=4}} Some of the hymns that Thomas wrote for the feast of Corpus Christi are still sung today, such as the ''[[Pange lingua gloriosi corporis mysterium|Pange lingua]]'' (whose final two verses are the famous ''[[Tantum ergo]]''), and ''[[Panis angelicus]]''. Modern scholarship has confirmed that Thomas was indeed the author of these texts, a point that some had contested.{{sfn|Torrell|2005|pp=129–132}}

In February 1265, the newly elected [[Pope Clement IV]] summoned Thomas to Rome to serve as papal theologian. This same year, he was ordered by the Dominican Chapter of Anagni<ref>{{cite web |url=http://www.corpusthomisticum.org/a65.html |title=Acta Capituli Provincialis OP Anagnie 1265 |website= corpusthomisticum.org}}</ref> to teach at the ''[[Medieval university|studium]]'' ''conventuale'' at the Roman [[convent]] of [[Santa Sabina]], founded in 1222.<ref name="auto">{{cite web |url=http://archive.org/details/MN5081ucmf_3 |title=Compendium historiae Ordinis Praedicatorum [microform] |last=Walz |first=Angelus |date=4 December 1930 |publisher=Romae : Herder |via=Internet Archive}}</ref> The ''studium'' at Santa Sabina now became an experiment for the Dominicans, the Order's first ''studium provinciale'', an intermediate school between the ''studium conventuale'' and the ''studium generale''. Prior to this time, the Roman Province had offered no specialized education of any sort, no arts, no philosophy; only simple convent schools, with their basic courses in theology for resident friars, were functioning in Tuscany and the meridionale during the first several decades of the order's life. The new ''studium provinciale'' at Santa Sabina was to be a more advanced school for the province.{{sfn|Mulchahey|1998|p=279}} [[Bartholomew of Lucca|Tolomeo da Lucca]], an associate and early biographer of Thomas, tells us that at the Santa Sabina ''studium'' Thomas taught the full range of philosophical subjects, both moral and natural.<ref>{{cite book| chapter-url= http://www.third-millennium-library.com/PDF/Authors/Gregorovius/history-of-rome-city_5_2.pdf | first= Ferdinand | last= Gregorovius|quote= Tenuit studium Rome, quasi totam Philosophiam, sive Moralem, sive Naturalem exposuit| chapter= Ptolomaei Lucensis historia ecclesiastica nova, xxii, c. 24| title= History of the City of Rome in the Middle Ages| volume= V| number= Part II, 617, Note 2 |archive-url= https://web.archive.org/web/20111005105213/http://www.third-millennium-library.com/PDF/Authors/Gregorovius/history-of-rome-city_5_2.pdf| archive-date=5 October 2011}}</ref>

While at the Santa Sabina ''studium provinciale'', Thomas began his most famous work, the ''[[Summa Theologica|Summa Theologiae]]'',{{sfn|Healy|2003|p=4}} which he conceived specifically suited to beginner students: "Because a doctor of Catholic truth ought not only to teach the proficient, but to him pertains also to instruct beginners. As the Apostle says in 1 Corinthians 3:1–2, ''as to infants in Christ, I gave you milk to drink, not meat'', our proposed intention in this work is to convey those things that pertain to the Christian religion in a way that is fitting to the instruction of beginners."<ref>''Summa theologiae'', I, 1, prooemium: "Quia Catholicae veritatis doctor non-solum provectos debet instruere, sed ad eum pertinet etiam incipientes erudire, secundum illud apostoli I ad Corinth. III, tanquam parvulis in Christo, lac vobis potum dedi, non-escam; propositum nostrae intentionis in hoc opere est, ea quae ad Christianam religionem pertinent, eo modo tradere, secundum quod congruit ad eruditionem incipientium."</ref> While there he also wrote a variety of other works like his unfinished ''[[Compendium Theologiae (Aquinas)|Compendium Theologiae]]'' and ''Responsio ad fr. Ioannem Vercellensem de articulis 108 sumptis ex opere Petri de Tarentasia'' (''Reply to Brother John of Vercelli Regarding 108 Articles Drawn from the Work of Peter of Tarentaise'').{{sfn|Stump|2003|p=xvii}}

In his position as head of the ''studium'', Thomas conducted a series of important disputations on the power of God, which he compiled into his ''De potentia''.{{sfn|Davies|2004|p=5}} Nicholas Brunacci [1240–1322] was among Thomas's students at the Santa Sabina ''studium provinciale'' and later at the Paris ''studium generale''. In November 1268, he was with Thomas and his associate and secretary [[Reginald of Piperno]] as they left Viterbo on their way to Paris to begin the academic year.<ref>{{cite web |url= http://www.brunacci.it/s--tommaso.html |title=Brunacci.it – Le famiglie Brunacci |website= brunacci.it}}</ref> Another student of Thomas's at the Santa Sabina ''studium provinciale'' was [[Beatification|Blessed]] Tommasello da Perugia.<ref>{{cite web |url= http://www.santiebeati.it/dettaglio/92060 |title=Beato Tommasello da Perugia su santiebeati.it |website=Santiebeati.it}}</ref>

Thomas remained at the ''studium'' at Santa Sabina from 1265 until he was called back to Paris in 1268 for a second teaching regency.{{sfn|Davies|2004|p=5}} With his departure for Paris in 1268 and the passage of time, the pedagogical activities of the ''studium provinciale'' at Santa Sabina were divided between two campuses. A new [[convent]] of the Order at the Church of [[Santa Maria sopra Minerva]] began in 1255 as a community for women converts but grew rapidly in size and importance after being given over to the Dominicans friars in 1275.<ref name="auto" /> In 1288, the theology component of the provincial curriculum for the education of the friars was relocated from the Santa Sabina ''studium provinciale'' to the ''studium conventuale'' at Santa Maria sopra Minerva, which was redesignated as a ''studium particularis theologiae''.{{sfn|Mulchahey|1998|p=323}} This ''studium'' was transformed in the 16th century into the College of Saint Thomas ({{langx|la|Collegium Divi Thomæ}}). In the 20th century, the college was relocated to the convent of [[Santi Domenico e Sisto|Saints Dominic and Sixtus]] and was transformed into the [[Pontifical University of Saint Thomas Aquinas]], (aka the ''Angelicum'').

===Quarrelsome second Paris regency (1269–1272)===
{{See also|Eternity of the world}}
[[File:Benozzo Gozzoli - Triumph of St Thomas Aquinas - WGA10334.jpg|thumb|''Triumph of St Thomas Aquinas'', {{lang|la|Doctor Communis}}, between Plato and Aristotle, [[Benozzo Gozzoli]], 1471. [[Louvre]], Paris.]]

In 1268, the Dominican Order assigned Thomas to be regent master at the University of Paris for a second time, a position he held until the spring of 1272. Part of the reason for this sudden reassignment appears to have arisen from the rise of "[[Averroism]]" or "radical [[Aristotelianism]]" in the universities. In response to these perceived errors, Thomas wrote two works, one of them being ''De unitate intellectus, contra Averroistas'' (''On the Unity of Intellect, against the Averroists'') in which he reprimands Averroism as incompatible with Christian doctrine.{{sfn|Stump|2003|pp=10–11}} During his second regency, he finished the second part of the ''Summa'' and wrote ''De virtutibus'' and ''De aeternitate mundi, contra murmurantes'' (''On the Eternity of the World, against Grumblers''),{{sfn|Davies|2004|p=5}} the latter of which dealt with controversial Averroist and Aristotelian ''beginninglessness'' of the world.{{sfn|Stump|2003|pp=11–12}}

Disputes with some important [[Franciscans]] conspired to make his second regency much more difficult and troubled than the first. A year before Thomas re-assumed the regency at the 1266–67 Paris disputations, Franciscan master William of Baglione accused Thomas of encouraging Averroists, most likely counting him as one of the "blind leaders of the blind". [[Eleonore Stump]] says, "It has also been persuasively argued that Thomas Aquinas's ''De aeternitate mundi'' was directed in particular against his Franciscan colleague in theology, [[John Pecham]]."{{sfn|Stump|2003|pp=11–12}}

Thomas was deeply disturbed by the spread of Averroism and was angered when he discovered [[Siger of Brabant]] teaching Averroistic interpretations of Aristotle to Parisian students.<ref>{{cite book| author= Thomas Aquinas| title= Reader| pages= 9–11}}</ref> On 10 December 1270, the Bishop of Paris, [[Étienne Tempier]], issued an edict condemning thirteen Aristotelian and Averroistic propositions as heretical and excommunicating anyone who continued to support them.<ref>McInerney, ''Against the Averroists'', p. 10.</ref> Many in the ecclesiastical community, the so-called [[Augustinians]], were fearful that this introduction of Aristotelianism and the more extreme Averroism might somehow contaminate the purity of the Christian faith. In what appears to be an attempt to counteract the growing fear of Aristotelian thought, Thomas conducted a series of disputations between 1270 and 1272: ''De virtutibus in communi'' (''On Virtues in General''), ''De virtutibus cardinalibus'' (''On Cardinal Virtues''), and ''De spe'' (''On Hope'').<ref>{{cite book| author= Thomas Aquinas| title= Reader| page= 11}}</ref>

===Late career and cessation of writing (1272–1274)===
[[File:Saint Patrick Church (Columbus, Ohio) - stained glass, St. Thomas Aquinas, detail.jpg|thumb|An icon of the crucifixion speaking to Thomas Aquinas is depicted on this stained glass window in [[Saint Patrick Church (Columbus, Ohio)]].]]

In 1272, Thomas took leave from the University of Paris when the Dominicans from his home province called upon him to establish a ''studium generale'' wherever he liked and staff it as he pleased. He chose to establish the institution in Naples and moved there to take his post as regent master.{{sfn|Davies|2004|p=5}} He took his time at Naples to work on the third part of the ''Summa'' while giving lectures on various religious topics. He also preached to the people of Naples every day in Lent of 1273. These [[s:Ninety-nine Homilies of S. Thomas Aquinas Upon the Epistles and Gospels for Forty-nine Sundays of the Christian Year|sermons]] on the Commandments, the Creed, the Our Father, and Hail Mary were very popular.<ref>{{cite book| first= James |last= Weisheipl| title= Friar Thomas D'Aquino: His Life, Thought, and Work| publisher=Doubleday| year= 1974| page= 319}}</ref>

Thomas has been traditionally ascribed with the ability to [[Levitation (paranormal)|levitate]] and as having had various mystical experiences. For example, [[G. K. Chesterton]] wrote that "His experiences included well-attested cases of levitation in ecstasy; and the Blessed Virgin appeared to him, comforting him with the welcome news that he would never be a Bishop."<ref>{{cite journal| first= G. K. |last= Chesterton| author-link= G. K. Chesterton| url= http://chesterton.org/gkc/theologian/aquinas.htm |title= Essay on St. Thomas Aquinas| journal= [[The Spectator]]| date= 27 February 1932| via= chesterton.org}}</ref> It is traditionally held that on one occasion, in 1273, at the Dominican convent of Naples in the chapel of [[Saint Nicholas]],<ref>{{cite web| url= http://www4.desales.edu/~philtheo/loughlin/ATP/Sermons/Nicholas_Essay.pdf| title= A Tale of Two Wonderworkers: St. Nicholas of Myra in the Writings and Life of St. Thomas Aquinas| first= Peter A.| last= Kwasniewski| publisher= International Theological Institute for Studies on Marriage and the Family Gaming, Austria| via= desales.edu| access-date= 19 March 2016| archive-date= 19 November 2018| archive-url= https://web.archive.org/web/20181119214628/http://www4.desales.edu/~philtheo/loughlin/ATP/Sermons/Nicholas_Essay.pdf| url-status= dead}}</ref> after [[Matins]], Thomas lingered and was seen by the [[sacristan]] Domenic of Caserta to be levitating in prayer with tears before an icon of the crucified Christ. Christ said to Thomas, "You have written well of me, Thomas. What reward would you have for your labor?" Thomas responded, "Nothing but you, Lord."{{sfnm |1a1=de Tocco |1a2=Le Brun-Gouanvic |1y=1996|1p= |2a1=Kennedy |2y=1912}}

On 6 December 1273, another mystical experience took place. While Thomas was celebrating Mass, he experienced an unusually long ecstasy.{{sfn|Kennedy|1912}} Because of what he saw, he abandoned his routine and refused to dictate to his ''socius'' [[Reginald of Piperno]]. When Reginald begged him to get back to work, Thomas replied: "Reginald, I cannot, because all that I have written seems like straw to me"{{sfn|Davies|1993|p=9}} (''mihi videtur ut palea'').<ref>{{Cite book |title=The Development and Meaning of Twentieth-century Existentialism |last=McBride |first=William Leon |publisher=Taylor and Francis |year=1997 |isbn=0-8153-2491-X |page=131}}</ref> As a result, the ''Summa Theologica'' would remain uncompleted.{{sfn|Murray|2013|p=27|loc=Ch. 10}} What exactly triggered Thomas's change in behaviour is believed by some to have been some kind of supernatural experience of God.<ref name="SEP2" /> After taking to his bed, however, he did recover some strength.{{sfn|Healy|2003|p=7}}

In 1274, [[Pope Gregory X]] summoned Thomas to attend the [[Second Council of Lyon]]. The council was to open 1 May 1274, and it was Gregory's attempt to try to heal the [[East-West Schism|Great Schism]] of 1054, which had divided the [[Catholic Church]] in the West from the [[Eastern Orthodox Church]].{{sfn|Nichols|2002|p=18}} At the meeting, Thomas's work for Pope Urban IV concerning the Greeks, ''Contra errores graecorum'', was to be presented.{{sfn|Hampden|1848|p=46}} However, on his way to the council, riding on a donkey along the [[Appian Way]],{{sfn|Nichols|2002|p=18}} he struck his head on the branch of a fallen tree and became seriously ill again. He was then quickly escorted to [[Monte Cassino]] to convalesce.{{sfn|Healy|2003|p=7}} After resting for a while, he set out again but stopped at the [[Cistercian]] [[Fossanova Abbey]] after again falling ill.{{sfn|Healy|2003|p=8}} The monks nursed him for several days,<ref>Thomas Aquinas, ''Reader'', p. 12.</ref> and as he received his [[last rites]] he prayed: "I have written and taught much about this very holy Body, and about the other sacraments in the faith of Christ, and about the Holy Roman Church, to whose correction I expose and submit everything I have written."{{sfn|Torrell|2005|p=292}} He died on 7 March 1274{{sfn|Healy|2003|p=8}} while giving commentary on the [[Song of Songs]].{{sfn|Hampden|1848|p=47}}

== Legacy, veneration, and modern reception ==

===Condemnation of 1277===
{{see also|Condemnations of 1210–1277}}

In 1277, [[Étienne Tempier]], the same bishop of Paris who had issued the condemnation of 1270, issued another, more extensive, condemnation. One aim of this condemnation was to clarify that God's absolute power transcended any principles of logic that [[Aristotle]] or [[Averroes]] might place on it.<ref>{{Cite book |title=The Foundations of Modern Science in the Middle Ages: Their Religious, Institutional, and Intellectual Contexts |last=Grant |first=Edward |publisher=Cambridge University Press |year=1996 |isbn=0-521-56762-9 |pages=81–82}}</ref> More specifically, it contained a list of 219 propositions, including twenty Thomistic propositions, that the bishop had determined to violate the omnipotence of God. The inclusion of the Thomistic propositions badly damaged Thomas's reputation for many years.{{sfn|Küng|1994|p=112<!--assumed from original ref name-->}}

===Canonization===
{{main|Canonization of Thomas Aquinas}}
[[File:Andrea di Bonaiuto. Santa Maria Novella 1366-7 fresco 0001.jpg|thumb|right|''Triumph of St. Thomas Aquinas'', {{lang|la|Doctor Angelicus}}, with saints and angels, [[Andrea di Bonaiuto]], 1366. [[Basilica of Santa Maria Novella]], fresco.]]
[[File:Nef-jacobins-toulouse.jpg|thumb|left|The remains of Thomas Aquinas are buried in the [[Church of the Jacobins]] in [[Toulouse]].]]

By the 1300s, however, Thomas's theology had begun its rise to prestige. In the ''[[Divine Comedy]]'' (completed {{Circa|1321|lk=no}}), [[Dante Alighieri|Dante]] sees the glorified soul of Thomas in the [[Paradiso (Dante) #Fourth Sphere (The Sun: The Wise)|Heaven of the Sun]] with the other great exemplars of religious wisdom.<ref>{{Cite book |author=Dante |title=Divine Comedy |title-link=Divine Comedy |chapter=''Parad''. x. 99 |author-link=Dante Alighieri |access-date=17 January 2010 |chapter-url=http://www.divinecomedy.org/divine_comedy.php3?display?Enface?Paradiso?10???148?1???0??1?1 |archive-url=https://web.archive.org/web/20110726001218/http://www.divinecomedy.org/divine_comedy.php3?display%3FEnface%3FParadiso%3F10%3F%3F%3F148%3F1%3F%3F%3F0%3F%3F1%3F1 |archive-date=26 July 2011 |url-status=dead |via=Divinecomedy.org}}</ref> [[Dante]] asserts that Thomas died by poisoning, on the order of [[Charles of Anjou]];<ref>{{Cite book |author=Dante Alighieri |title=Divine Comedy |chapter=''Purg''. xx. 69 |access-date=17 January 2010 |chapter-url=http://www.divinecomedy.org/divine_comedy.php3?display?Enface?Purgatorio?20???151?1???0??1?1 |archive-url=https://web.archive.org/web/20110726001228/http://www.divinecomedy.org/divine_comedy.php3?display%3FEnface%3FPurgatorio%3F20%3F%3F%3F151%3F1%3F%3F%3F0%3F%3F1%3F1 |archive-date=26 July 2011 |url-status=dead |via=Divinecomedy.org}}</ref> Villani{{who|date=January 2025}} cites this belief,{{citation needed|date=January 2025|reason=broken ref "Villani (ix. 218)."}} and the ''[[Anonimo Fiorentino]]'' describes the crime and its motive. But the historian [[Ludovico Antonio Muratori]] reproduces the account made by one of Thomas's friends, and this version of the story gives no hint of foul play.<ref name="britannica-250">{{EB1911|wstitle=Thomas Aquinas|volume=2|last1=Lindsay|first1=Thomas Martin|author1-link=Thomas Martin Lindsay|last2=Mitchell|first2=John Malcolm|author2-link=|pages=250–252|short=1}}</ref>

When the [[devil's advocate]] at his [[canonization]] process objected that there were no [[miracle]]s, one of the cardinals answered, "{{lang|la|Tot miraculis, quot articulis}}"—"there are as many miracles (in his life) as articles (in his [[Summa Theologica|''Summa'']])".<ref name="Mullady" /> Fifty years after Thomas's death, on 18 July 1323, [[Pope John XXII]], seated in [[Avignon]], pronounced Thomas a [[saint]].{{sfn|Hampden|1848|p=54}}

A monastery at Naples, Italy, near [[Naples Cathedral]], shows a cell in which he supposedly lived.<ref name="britannica-250" /> His remains were translated from Fossanova to the [[Church of the Jacobins]] in [[Toulouse]], France, on 28 January 1369. Between 1789 and 1974, they were held in the [[Basilica of Saint-Sernin, Toulouse|Basilica of Saint-Sernin]]. In 1974, they were returned to the Church of the Jacobins, where they have remained ever since.

When he was canonized, his feast day was inserted in the [[General Roman Calendar]] for celebration on 7 March, the day of his death. Since this date commonly falls within [[Lent]], the [[Mysterii Paschalis|1969 revision of the calendar]] moved his [[memorial (liturgy)|memorial]] to 28 January, the date of the translation of his relics to [[Church of the Jacobins]], [[Toulouse]].<ref>''Calendarium Romanum'' Libreria Editrice Vaticana 1969, p. 86</ref><ref>''Liturgy of the Hours'' Volume III, Proper of Saints, 28 January.</ref>

Thomas Aquinas is honored with a [[feast day]] in some churches of the [[Anglican Communion]] with a [[Lesser Festival (Anglicanism)|Lesser Festival]] on 28 January.<ref>{{cite web |title=The Calendar |url=https://www.churchofengland.org/prayer-and-worship/worship-texts-and-resources/common-worship/churchs-year/calendar |access-date=27 March 2021 |website=The Church of England |language=en}}</ref>

The Catholic Church honours Thomas Aquinas as a [[saint]] and regards him as the model teacher for those studying for the priesthood. In modern times, under papal directives, the study of his works was long used as a core of the required program of study for those seeking ordination as priests or deacons, as well as for those in religious formation and for other students of the sacred disciplines (philosophy, Catholic theology, church history, liturgy, and [[canon law (Catholic Church)|canon law]]).<ref>Code of [[Canon Law]], Can. 252, §3 {{cite web |url= https://www.vatican.va/archive/ENG1104/__PW.HTM |title=Code of Canon Law |website=vatican.va |url-status=dead |archive-url= https://web.archive.org/web/20110508022209/https://www.vatican.va/archive/ENG1104/__PW.HTM |archive-date=8 May 2011 |access-date=22 March 2011}}</ref>

=== Doctor of the Church and second scholasticism ===
[[Pope Pius V]] proclaimed St. Thomas Aquinas a [[Doctor of the Church]] on 15 April 1567,<ref>{{cite book |last=Torrell |first=Jean-Pierre |translator-last1=Minerd |translator-first1=Matthew K. |translator-last2=Royal |translator-first2=Robert |translator-link2=Robert Royal (author) |date=2023 |title=Saint Thomas Aquinas, Vol. 1: The Person and His Work |url=https://books.google.com/books?id=Gvi0EAAAQBAJ |location= |publisher=[[The Catholic University of America Press]] |page=376 |isbn=978-0-8132-3560-8}}</ref> and ranked his feast with those of the four great Latin fathers: [[Ambrose]], [[Augustine of Hippo]], [[Jerome]], and [[Pope Gregory I|Gregory]].<ref name="britannica-250" /> At the [[Council of Trent]], Thomas had the honour of having his ''Summa Theologiae'' placed on the altar alongside the Bible and the [[Decretals]].{{sfn|Küng|1994|p=112<!--assumed from original ref name-->}}<ref name="Mullady">{{cite web |url= http://www.holyspiritinteractive.net/columns/guests/brianmullady/thomasaquinas.asp |title=The Angelic Doctor – Thomas Aquinas |last= Mullady |first=Brian |year=2006 |url-status=dead |archive-url= https://web.archive.org/web/20081007031948/http://www.holyspiritinteractive.net/columns/guests/brianmullady/thomasaquinas.asp |archive-date=7 October 2008 |access-date=11 June 2011}}</ref> This happened within the historical timeframe of the "[[second scholasticism]]", a trend during the 16th and 17th centuries that saw renewed interest in the works of scholars of the 12th, 13th, and 14th centuries, in spite of [[humanism]] as a contrary trend. Second scholasticism gave special emphasis to the works of Thomas Aquinas and [[Duns Scotus|John Duns Scotus]], with more Franciscans following Duns Scotus, and more Dominicans and Carmelites following Thomas.<ref>{{Cite journal |last=Heider |first=Daniel |date=2012 |title=The Variety of Second Scholasticism: Introduction |journal=[[Res Philosophica|The Modern Schoolman]] |volume=89 |issue=1/2 |pages=3–7 |doi=10.5840/schoolman2012891/22}}</ref> "Thomists", or those following Thomas, included [[Francisco de Vitoria]], [[Thomas Cajetan]], [[Francesco Silvestri|Franciscus Ferrariensis]], [[Domingo de Soto]], [[Domingo Báñez]], [[João Poinsot]], the [[Complutenses]] and others.

=== Neo-scholasticism and Catholic ''Nouvelle théologie'' ===
During the 19th century, a movement that came to be known as [[neo-scholasticism]] revived Catholic scholarly interest in scholasticism generally and Thomas in particular, as well as the work of the Thomists of second scholasticism. The systematic work of Thomas was valued in part as a foundation for arguing against [[Early modern philosophy|early modern philosophers]] and "modernist" theologians. A good example is ''[[Aeterni Patris]]'', the 1879 [[encyclical]] by [[Pope Leo XIII]] stating that Thomas's theology was a definitive exposition of Catholic doctrine. Leo XIII directed the clergy to take the teachings of Thomas as the basis of their theological positions. Leo also decreed that all Catholic seminaries and universities must teach Thomas's doctrines, and where Thomas did not speak on a topic, the teachers were "urged to teach conclusions that were reconcilable with his thinking." In 1880, Thomas Aquinas was declared the patron saint of all Catholic educational establishments.<ref name="britannica-250" /> Similarly, in ''[[Pascendi Dominici gregis]]'', the 1907 encyclical by [[Pope Pius X]], the Pope said, "...let Professors remember that they cannot set St. Thomas aside, especially in metaphysical questions, without grave detriment."<ref>{{Citation |last=Pius X |title=Pascendi Dominicis gregis |date=8 September 1907 |url=https://www.vatican.va/content/pius-x/en/encyclicals/documents/hf_p-x_enc_19070908_pascendi-dominici-gregis.html |author-link=Pope Pius X}}</ref> On 29 June 1923, on the sixth centenary of his canonisation, [[Pope Pius XI]] dedicated the encyclical ''[[Studiorum Ducem]]'' to him.

In response to neo-scholasticism, Catholic scholars who were more sympathetic to modernity gained influence during the early 20th century in the ''[[nouvelle théologie]]'' movement (meaning "new theology"). It was closely associated with a movement of ''ressourcement'', meaning "back to sources", echoing the phrase "''[[ad fontes]]''" used by Renaissance humanists. Although ''nouvelle théologie'' disagreed with neo-scholasticism about modernity, arguing that theology could learn much from modern philosophy and science, their interest in also studying "old" sources meant that they found common ground in their appreciation of scholastics like Thomas Aquinas.<ref name=":0">{{Cite book |last=Mettepenningen |first=Jürgen |title=Nouvelle théologie – new theology : inheritor of modernism, precursor of Vatican II |publisher=[[T&T Clark]] |year=2002 |isbn=9780567697301 |location=London, England}}</ref> The [[Second Vatican Council]] generally adopted the stance of the theologians of ''nouvelle théologie,'' but the importance of Thomas was a point of agreement.<ref name=":0" /> The council's decree ''[[Optatam Totius]]'' (on the formation of priests, at No. 15), proposed an authentic interpretation of the popes' teaching on Thomism, requiring that the theological formation of priests be done with Thomas Aquinas as teacher.<ref>{{cite web|url=https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_decree_19651028_optatam-totius_en.html|quote=Next, in order that they may illumine the mysteries of salvation as completely as possible, the students should learn to penetrate them more deeply with the help of speculation, under the guidance of St. Thomas, and to perceive their interconnections.|title=Optatam Totius}}</ref>

With 70 quotes, prevalently in the field of [[Catholic liturgy]], Aquinas is one of the most frequently cited authors of the 1997 [[Catechism of the Catholic Church]].<ref>{{cite journal | jstor=44617298 | title=La teologia nella liturgia e la liturgia nella teologia in san Tommaso d'Aquino | last1=Fuente | first1=Antolín González | journal=Angelicum | date=1997 | volume=74 | issue=3 | pages=359–417 }}</ref>

General Catholic appreciation for Thomas has remained strong in the 20th century, as seen in the praise offered by Pope John Paul II in the 1998 encyclical ''[[Fides et ratio]],''<ref>{{cite web |title=Fides et ratio (14 September 1998) |url=https://www.vatican.va/content/john-paul-ii/en/encyclicals/documents/hf_jp-ii_enc_14091998_fides-et-ratio.html}} (at No. 43).</ref> and similarly in [[Pope Benedict XV]]'s 1921 encyclical ''Fausto Appetente Die.''<ref>[[Pope Benedict XV|Benedict XV]], Encyclical [https://www.vatican.va/holy_father/benedict_xv/encyclicals/documents/hf_ben-xv_enc_29061921_fausto-appetente-die_en.html ''Fausto appetente die'']. {{Webarchive|url=https://web.archive.org/web/20140221101408/http://www.vatican.va/holy_father/benedict_xv/encyclicals/documents/hf_ben-xv_enc_29061921_fausto-appetente-die_en.html|date=21 February 2014}}. 29 June 1921, AAS 13 (1921), p. 332; [[Pius XI]], Encyclical ''Studiorum Ducem,'' §11, 29 June 1923, AAS 15 (1923), cf. AAS 17 (1925), p. 574; [[Paul VI]], 7 March 1964, AAS 56 (1964), p. 302 (Bouscaren, vol. VI, pp. 786–788).</ref>

=== Modern philosophical influence ===
[[File:Saint Joseph's Catholic Church (Central City, Kentucky) - stained glass, St. Thomas Aquinas, detail.jpg|thumb|A stained glass window of Thomas Aquinas in St. Joseph's Catholic Church ([[Central City, Kentucky]])]]

Some modern ethicists within the Catholic Church (notably [[Alasdair MacIntyre]]) and outside it (notably [[Philippa Foot]]) have recently commented on the possible use of Thomas's [[virtue ethics]] as a way of avoiding [[utilitarianism]] or Kantian "sense of duty" (called [[deontology]]).<ref>{{cite book |editor1-last=Snow |editor1-first=Nancy E. |title=The Oxford Handbook of Virtue |date=2018 |publisher=Oxford University Press |isbn=9780199385195 |page=322 |url=https://books.google.com/books?id=g8Q9DwAAQBAJ&pg=PA322}}</ref> Through the work of twentieth-century philosophers such as [[G. E. M. Anscombe|Elizabeth Anscombe]] (especially in her book ''Intention''), Thomas's [[principle of double effect]] specifically and his theory of intentional activity generally have been influential.{{Citation needed|date=October 2019}}

The cognitive neuroscientist [[Walter J. Freeman (neuroscientist)|Walter Freeman]] has proposed that Thomism is the philosophical system explaining cognition that is most compatible with [[neurodynamics]].<ref>{{Cite journal |last=Freeman |first=Walter |date=2008-01-01 |title=Nonlinear Brain Dynamics and Intention According to Aquinas |url=https://www.ingentaconnect.com/content/imp/mm/2008/00000006/00000002/art00005 |journal=Mind and Matter |volume=6 |issue=2 |pages=207–234}}</ref>

[[Henry Adams]]'s ''[[Mont Saint Michel and Chartres]]'' ends with a culminating chapter on Thomas, in which Adams calls Thomas an "artist" and constructs an extensive analogy between the design of Thomas's "Church Intellectual" and that of the gothic cathedrals of that period. [[Erwin Panofsky]] later would echo these views in ''Gothic Architecture and Scholasticism'' (1951).<ref>{{Cite book|url=https://archive.org/details/gothicarchitectu0000unse_e4n9 |title=Gothic Architecture and Scholasticism|last=Panofsky|first=Erwin|date=1957 |orig-date=1951 |publisher=Meridian Books |location=New York |isbn=978-0-529-02092-5|language=en}}</ref>

Thomas's aesthetic theories, especially the concept of ''claritas'', deeply influenced the literary practice of modernist writer [[James Joyce]], who used to extol Thomas as being second only to Aristotle among Western philosophers. Joyce refers to Thomas's doctrines in ''Elementa philosophiae ad mentem D. Thomae Aquinatis doctoris angelici'' (1898) of Girolamo Maria Mancini, professor of theology at the [[Pontifical University of Saint Thomas Aquinas|Collegium Divi Thomae de Urbe]].{{sfn|Anon.|1899|p=570}} For example, Mancini's ''Elementa'' is referred to in Joyce's ''[[Portrait of the Artist as a Young Man]]''.<ref>{{Cite book |last=Joyce |first=James |url=https://archive.org/details/portraitofartist00jame |title=A Portrait of the Artist as a Young Man |publisher=Wordsworth Editions |year=1992 |isbn=978-1853260063 |page=[https://archive.org/details/portraitofartist00jame/page/221 221] |url-access=registration |via=Internet Archive}}</ref>

The influence of Thomas's aesthetics can also be found in the works of the Italian [[semiotics|semiotician]] [[Umberto Eco]], who wrote an essay on aesthetic ideas in Thomas (published in 1956 and republished in 1988 in a revised edition).<ref>{{Cite book |last=Umberto |first=Eco |title=The Aesthetics of Thomas Aquinas |publisher=[[Harvard University Press]] |year=1988 |isbn=978-0674006768 |translator-last=Bredin |translator-first=Hugh}}</ref>

=== Modern criticism ===

Twentieth-century philosopher [[Bertrand Russell]] criticized Thomas's philosophy, stating that:

<blockquote>He does not, like the Platonic Socrates, set out to follow wherever the argument may lead. He is not engaged in an inquiry, the result of which it is impossible to know in advance. Before he begins to philosophize, he already knows the truth; it is declared in the Catholic faith. If he can find apparently rational arguments for some parts of the faith, so much the better; if he cannot, he need only fall back on revelation. The finding of arguments for a conclusion given in advance is not philosophy, but [[special pleading]]. I cannot, therefore, feel that he deserves to be put on a level with the best philosophers either of Greece or of modern times.<ref>{{harv|Russell|1967|p=463}}. ''[[A History of Western Philosophy]]'', Ch. 34, "St. Thomas Aquinas", Allen & Unwin, London, England; Simon & Schuster, New York 1946, pp. 484–.</ref>
</blockquote>

This criticism is illustrated with the following example: according to Russell, Thomas advocates the indissolubility of marriage "on the ground that the father is useful in the education of the children, (a) because he is more rational than the mother, (b) because, being stronger, he is better able to inflict physical punishment."<ref name="Russell 1967 462">{{harv|Russell|1967|p=462}}.</ref> Even though modern approaches to education do not support these views, "No follower of Saint Thomas would, on that account, cease to believe in lifelong monogamy, because the real grounds of belief are not those which are alleged".<ref name="Russell 1967 462" />

===In arts===
According to Alfredo Cattabiani<sub>[[w:it:Alfredo Cattabiani|it]]</sub>:<ref>Alfredo Cattabiani, ''Santi d'Italia. Vite, leggende, iconografia, feste, patronati, culto'', [[w:it:Biblioteca Universale Rizzoli|Biblioteca Universale Rizzoli]], [[Milan|Milano]] 1993, p. 895. ({{ISBN|9788817068345}}, {{OCLC|493456561}}, related to 2004 edition). 

As quoted in {{cite journal|first1=Mauro (Pontifical Salesian University and Prefect of the Vatican Library)|last1=Mantovani|language=it|url=https://www.academia.edu/76977750|journal=Salesianum|publisher=[[Salesian Pontifical University]]|title=Tommaso d'Aquino: sapienza e carità nella ricerca di Dio|trans-title=Thomas Aquinas: wisdom and charity in the search for God|format=PDF|date=September 1, 2022|volume=64|issue=3|pages=431–444|issn=3035-4293|doi=10.63343/nf2321qw|access-date=March 27, 2025|archive-url=https://web.archive.org/web/20250327170029/https://www.academia.edu/76977750/Tommaso_dAquino_sapienza_e_carit%C3%A0_nella_ricerca_di_Dio?email_work_card=title|archive-date=March 27, 2025|url-status=live}} ({{oclc|10704458408}}, also freely available on [[Academia.edu]]) (''ivi'': pp. 1-2 of the PDF file)</ref>
{{blockquote|An attribute often found in his portraits is a ray of light on the saint's chest or shoulder: often the rays emanate from the book of the Summa that is open on his chest. But the radiating light [...] is not the only attribute: often a [[Doves as symbols#Christianity|dove]] appears as a symbol of the Holy Spirit, sometimes a [[lily]] to emphasise his [[chastity]] or a [[chalice#Christian|chalice]]; and finally a model of a church as in the panel of the Dominican saints in the [[sacristy]] of [[Santa Maria Novella]] in [[Florence]].}}
Aquinas is often depicted in a Dominican habit with a [[cincture]] that refers to his prayers to God for being kept in perpetual virginity. Chalice refers to his doctrine of Eucharistic [[transubstantiation]].<ref>In the [[Berlin Museum]], for example, there is a panel depicting Saint Thomas: the artist, from the school of [[Bernardo Daddi]], imagines and depicts angels girding the hips of the saint, absorbed in prayer, while they communicate to him that his prayer to the Lord for the ''perpetuae virginitatis cingulum'' had been accepted. Cfr. C.M.J.Vanstenkiste - M.C. Celletti, ''Tommaso d'Aquino'', in ''Bibliotheca Sanctorum'' XII, Roma 1969, coll. 544-566, specialmente 563-566; P.
Amargier, ''Tommaso d’Aquino'', in A. Vauchez (ed.), ''Storia dei santi e della santità cristiana'' Ch. VI. ''L'epoca del rinnovamento evangelico 1054-1274'', Milano 1991, pp. 245-260.</ref>

==Theology==
{{Catholic philosophy}}

Thomas Aquinas viewed theology, "the sacred [[doctrine]]", as a science,<ref name="SEP2" /> by which he meant a field of study in which humanity could learn more by its own efforts (as opposed to being totally dependent on having divine revelation planted into our minds). For Thomas, the raw material data of this field consists of written [[Sacred Tradition|scripture]] and the tradition of the Catholic Church. These sources of data were produced by the self-revelation of God to individuals and groups of people throughout history. Faith and reason, being distinct but related, are the two primary tools for processing the data of theology. Thomas believed both were necessary—or, rather, that the ''confluence'' of both was necessary—for one to obtain true knowledge of God.<ref name="SEP2" />

Thomas blended Greek philosophy and Christian doctrine by suggesting that rational thinking and the study of nature, like revelation, were valid ways to understand truths pertaining to God. According to Thomas, God reveals himself through nature, so to study nature is to study God. The ultimate goals of theology, in Thomas's mind, are to use reason to grasp the truth about God and to experience salvation through that truth. The central thought is "[[gratia non tollit naturam, sed perficit]]" ('[[divine grace|grace]] does not destroy nature, but perfects it').<ref name="SEP2" />

===Revelation===
Thomas believed that truth is known through reason, rationality ([[natural revelation]]) and faith ([[supernatural revelation]]). ''Supernatural'' revelation has its origin in the inspiration of the Holy Spirit and is made available through the teaching of the prophets, summed up in Holy Scripture, and transmitted by the [[Magisterium]], the sum of which is called "Tradition". ''Natural'' revelation is the truth available to all people through their human nature and powers of reason. For example, he felt this applied to rational ways to know the existence of God.

Though one may deduce the existence of God and his Attributes (Unity, Truth, Goodness, Power, Knowledge) through reason, certain specifics may be known only through the special revelation of God through [[Jesus Christ]]. The major theological components of Christianity, such as the [[Trinity]], the [[Incarnation]], and charity are revealed in the teachings of the church and the [[scripture]]s and may not otherwise be deduced.<ref>{{Cite book |last=Hankey |first=Wayne |title=The Routledge Companion to Philosophy of Religion |publisher=Routledge |year=2013 |isbn=978-0-415-78295-1 |edition=Second |location=CSU East Bay |pages=134–135}}</ref> However, Thomas also makes a distinction between "demonstrations" of sacred doctrines and the "persuasiveness" of those doctrines.<ref name="autogenerated1">{{cite web |date= |title=Aquinas' Philosophical Theology &#124; Internet Encyclopedia of Philosophy |url=https://iep.utm.edu/thomas-aquinas-political-theology/#SH3c |access-date=7 August 2022 |publisher=Iep.utm.edu}}</ref> The former is akin to something like "certainty", whereas the latter is more probabilistic in nature.<ref name="autogenerated1" />

In other words, Thomas thought Christian doctrines were "fitting" to reason (i.e. reasonable), even though they cannot be demonstrated beyond a reasonable doubt.<ref name="autogenerated1" /> In fact, the ''Summa Theologica'' is filled with examples of Thomas arguing that we would expect certain Christian doctrines to be true, even though these expectations are not demonstrative (i.e. 'fitting' or reasonable).<ref name="Iep.utm.edu">{{cite web |date= |title=Aquinas' Philosophical Theology &#124; Internet Encyclopedia of Philosophy |url=https://iep.utm.edu/thomas-aquinas-political-theology/#H4 |access-date=7 August 2022 |publisher=Iep.utm.edu}}</ref> For example, Thomas argues that we would expect God to become incarnate, and we would expect a resurrected Christ to ''not'' stay on Earth.<ref name="Iep.utm.edu" /><ref>{{cite web |date= |title=Summa Theologiae: The ascension of Christ (Tertia Pars, Q. 57) |url=https://www.newadvent.org/summa/4057.htm#article1 |access-date=7 August 2022 |publisher=Newadvent.org}}</ref>

====Reconciling faith and reason====
According to Thomas, faith and reason complement rather than [[Fideism|contradict each other]], each giving different views of the same truth. A discrepancy between faith and reason arises from a shortcoming of either natural science or scriptural interpretation. Faith can reveal a divine mystery that eludes scientific observation. On the other hand, science can suggest where fallible humans misinterpret a scriptural metaphor as a literal statement of fact.<ref>{{cite news |last=Beattie |first=Tina |date=13 February 2012 |title=Thomas Aquinas, part 3: scripture, reason and the being of God |newspaper=The Guardian |publisher=www.theguardian.com |url=https://www.theguardian.com/commentisfree/belief/2012/feb/13/scripture-reason-god-thomas-aquinas |access-date=25 March 2023}}</ref>

=== God ===
[[Augustine of Hippo]]'s reflection on divine essentiality or [[essentialist]] theology would influence [[Richard of St. Victor]], [[Alexander of Hales]], and [[Bonaventure]]. By this method, the [[essence]] of God is defined by what God is, and also by describing what God is not ([[negative theology]]). Thomas took the text of [[Book of Exodus|Exodus]] beyond the explanation of essential theology. He bridged the gap of understanding between the being of essence and the being of existence. In [[Summa Theologica]], the way is prepared with the proofs for the existence of God. All that remained was to recognize the God of [[Book of Exodus|Exodus]] as having the nature of "Him Who is the supreme act of being". God is simple, there is no composition in God. In this regard, Thomas relied on [[Boethius]] who in turn followed the path of [[Platonism]], something Thomas usually avoided.<ref name="Gilson, Etienne 1994, pp. 84">Gilson, Etienne, ''The Christian Philosophy of St. Thomas Aquinas'', University of Notre Dame Press, 1994, pp.&nbsp;84–95.</ref>

The conclusion was that the meaning of "I Am Who I Am" is not an enigma to be answered, but a statement of the essence of God. This is the discovery of Thomas: the essence of God is not described by negative analogy, but the "essence of God is to exist". This is the basis of "[[existential theology]]" and leads to what Gilson calls the first and only [[existential philosophy]]. In Latin, this is called "Haec Sublimis Veritas", "the sublime truth". The revealed essence of God is to exist, or in the words of Thomas, "I am the pure Act of Being". This has been described as the key to understanding [[Thomism]]. Thomism has been described (as a philosophical movement), as either the emptiest or the fullest of philosophies.<ref name="Gilson, Etienne 1994, pp. 84" />

===Creation===
[[File:Tommaso - Super libros de generatione et corruptione - 4733257 00007.tif|thumb|''Super libros de generatione et corruptione'']]
{{further|abiogenesis|spontaneous generation}}

As a Catholic, Thomas believed that God was the "maker of heaven and earth, of all that is visible and invisible." But he thought that this fact can be proved by natural reason; indeed, in showing that it is necessary that any existent being has been created by God, he uses only philosophical arguments, based on his metaphysics of participation.<ref>See Thomas Aquinas, {{lang|la|Summa Theologiae}} I, q. 44, a. 1, co ([https://www.corpusthomisticum.org/sth1044.html#30287 Latin] and [https://isidore.co/aquinas/english/summa/FP/FP044.html#FPQ44A1THEP1 English]).</ref> He also maintains that God creates {{lang|la|ex nihilo}}, from nothing, that is he does not make use of any preexisting matter.<ref>See {{lang|la|Summa Theologiae}} I, q. 44, a. 2 ([https://www.corpusthomisticum.org/sth1044.html#30291 Latin] and [https://isidore.co/aquinas/english/summa/FP/FP044.html#FPQ44A2THEP1 English]), and q. 45, a. 1 ([https://www.corpusthomisticum.org/sth1044.html#30320 Latin] and [https://isidore.co/aquinas/english/summa/FP/FP045.html#FPQ45A1THEP1 English]).</ref> On the other hand, Thomas thought that the fact that the world started to exist by God's creation and is not eternal is only known to us by faith; it cannot be proved by natural reason.<ref>See {{lang|la|Summa Theologiae}} I, q. 46, aa. 1–2 ([https://www.corpusthomisticum.org/sth1044.html#30388 Latin] and [https://isidore.co/aquinas/english/summa/FP/FP046.html#FPQ46A1THEP1 English]).</ref>

Like Aristotle, Thomas posited that life could form from non-living material or plant life:

{{blockquote|Since the generation of one thing is the corruption of another, it was not incompatible with the first formation of things, that from the corruption of the less perfect the more perfect should be generated. Hence animals generated from the corruption of inanimate things, or of plants, may have been generated then.<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter-url= https://www3.nd.edu/~afreddos/summa-translation/Part%201/st1-ques72.pdf |chapter= On the Work of the Sixth Day, Reply to Objection 5| translator=| via= NDPR}}</ref>}}
[[File:Tommaso d'Aquino – Super Physicam Aristotelis, 1595 – BEIC 4733624.jpg|thumb|''Super Physicam Aristotelis'', 1595]]
Additionally, Thomas considered [[Empedocles]]'s theory that various mutated [[species]] emerged at the dawn of Creation. Thomas reasoned that these species were generated through [[mutation]]s in animal [[sperm]], and argued that they were not unintended by [[nature]]; rather, such species were simply not intended for perpetual existence. That discussion is found in his commentary on Aristotle's ''[[Physics (Aristotle)|Physics]]'':

{{blockquote|The same thing is true of those substances Empedocles said were produced at the beginning of the world, such as the 'ox-progeny', i.e., half ox and half-man. For if such things were not able to arrive at some end and final state of nature so that they would be preserved in existence, this was not because nature did not intend this [a final state], but because they were not capable of being preserved. For they were not generated according to nature, but by the corruption of some natural principle, as it now also happens that some monstrous offspring are generated because of the corruption of seed.<ref>Saint Thomas Aquinas, [http://dhspriory.org/thomas/Physics2.htm#14 Physica] {{Webarchive|url=https://web.archive.org/web/20141228130315/http://dhspriory.org/thomas/Physics2.htm#14 |date=28 December 2014 }}, ''Book 2, Lecture 14'', Fathers of the English Dominican Province</ref>}}

===Nature of God===
Thomas believed that the [[existence of God]] is self-evident in itself, but not to us. "Therefore, I say that this proposition, "God exists", of itself is self-evident, for the predicate is the same as the subject{{nbsp}}... Now because we do not know the essence of God, the proposition is not self-evident to us; but needs to be demonstrated by things that are more known to us, though less known in their nature—namely, by effects."<ref>{{Cite book |author=Thomas Aquinas |title=Summa Theologica |chapter=The Existence of God (Prima Pars, Q. 2) |chapter-url=http://www.newadvent.org/summa/1002.htm#article1 |via=newadvent.org}}</ref>

Thomas believed that the existence of God can be demonstrated. Briefly in the ''Summa Theologiae'' and more extensively in the ''[[Summa contra Gentiles]]'', he considered in great detail five arguments for the existence of God, widely known as the ''[[quinque viae]]'' (Five Ways).

# Motion: Some things undoubtedly move, though cannot cause their own motion. Since, as Thomas believed, there can be no infinite chain of causes of motion, there must be a [[Unmoved mover|First Mover]] not moved by anything else, and this is what everyone understands by God.
# Causation: As in the case of motion, nothing can cause itself, and an infinite chain of causation is impossible, so there must be a [[Prima causa|First Cause]], called God.
# Existence of necessary and the unnecessary: Our experience includes things certainly existing but apparently unnecessary. Not everything can be unnecessary, for then once there was nothing and there would still be nothing. Therefore, we are compelled to suppose something that exists necessarily, having this necessity only from itself; in fact itself the cause for other things to exist.
# Gradation: If we can notice a gradation in things in the sense that some things are more hot, good, etc., there must be a superlative that is the truest and noblest thing, and so most fully existing. This then, we call God.{{efn|name=qualities}}
# Ordered tendencies of nature: A direction of actions to an end is noticed in all bodies following natural laws. Anything without awareness tends to a goal under the guidance of one who is aware. This we call God.{{efn|name=objects}}<ref>''Summa of Theology'' I, q.2, "The Five Ways Philosophers Have Proven God's Existence".</ref>

Thomas was receptive to and influenced by [[Avicenna]]'s [[Proof of the Truthful]].<ref>Adamson, Peter (2013). "From the necessary existent to God". In Adamson, Peter (ed.). ''Interpreting Avicenna: Critical Essays''. Cambridge University Press. {{ISBN|978-0521190732}}.</ref> Concerning the nature of God, Thomas, like Avicenna felt the best approach, commonly called the ''[[negative theology|via negativa]]'', was to consider what God is not. This led him to propose five statements about the divine qualities:
# [[divine simplicity|God is simple]], without composition of parts, such as body and soul, or matter and form.{{sfn|Kreeft|1990|pp=74–77}}
# God is perfect, lacking nothing. That is, God is distinguished from other beings on account of God's complete actuality.{{sfn|Kreeft|1990|pp=86–87}} Thomas defined God as the Ipse [[Actus Essendi]] subsistens, subsisting act of being.<ref>''Actus Essendi'' and the Habit of the First Principle in Thomas Aquinas (New York: Einsiedler Press, 2019).</ref>
# God is infinite. That is, God is not finite in the ways that created beings are physically, intellectually, and emotionally limited. This infinity is to be distinguished from infinity of size and infinity of number.{{sfn|Kreeft|1990|pp=97–99}}
# God is immutable, incapable of change on the levels of God's essence and character.{{sfn|Kreeft|1990|p=105}}
# God is one, without diversification within God's self. The unity of God is such that God's essence is the same as God's existence. In Thomas's words, "in itself the proposition 'God exists' is [[logical truth|necessarily true]], for in it subject and predicate are the same."{{sfn|Kreeft|1990|pp=111–112}}

===Nature of sin===
Following [[Augustine of Hippo]], Thomas defines [[sin]] as "a word, deed, or desire, contrary to the [[Divine law|eternal law]]."<ref>{{Cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II-I |chapter=Question 71, Article 6 |access-date=17 January 2010 |chapter-url=http://www.newadvent.org/summa/2071.htm#article6 |via=newadvent.org}}</ref> It is important to note the analogous nature of law in Thomas's legal philosophy. Natural law is an instance or instantiation of eternal law. Because natural law is what human beings determine according to their own nature (as rational beings), disobeying reason is disobeying natural law and eternal law. Thus eternal law is logically prior to reception of either "natural law" (that determined by reason) or "divine law" (that found in the Old and New Testaments). In other words, God's will extends to both reason and revelation. Sin is abrogating either one's own reason, on the one hand, or revelation on the other, and is synonymous with "evil" ([[privation]] of good, or ''[[privatio boni]]''<ref>{{cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II-I |chapter=Question 75, Article 1 |quote=For evil is the absence of the good, which is natural and due to a thing. |chapter-url=http://www.newadvent.org/summa/2075.htm#article1}}</ref>). Thomas, like all Scholastics, generally argued that the findings of reason and data of revelation cannot conflict, so both are a guide to God's will for human beings.

===Nature of the Trinity===
Thomas argued that God, while perfectly united, also is perfectly described by [[Trinity|Three Interrelated Persons]]. These three persons (Father, Son, and Holy Spirit) are constituted by their relations within the essence of God. Thomas wrote that the term "Trinity" "does not mean the relations themselves of the Persons, but rather the number of persons related to each other; and hence it is that the word in itself does not express regard to another."<ref>{{Cite book |author=Thomas Aquinas |title=Summa Theologica |chapter=The unity or plurality in God (Prima Pars, Q. 31) |chapter-url=http://www.newadvent.org/summa/1031.htm#article3 |via=newadvent.org}}</ref> The Father generates the Son (or the Word) by the relation of self-awareness. This eternal generation then produces an eternal Spirit "who enjoys the divine nature as the Love of God, the Love of the Father for the Word."

This Trinity exists independently from the world. It transcends the created world, but the Trinity also decided to give grace to human beings. This takes place through the [[Incarnation (Christianity)|Incarnation]] of the Word in the person of [[Jesus Christ]] and through the indwelling of the [[Holy Spirit in Christianity|Holy Spirit]] within those who have experienced [[salvation]] by God; according to Aidan Nichols.{{sfn|Nichols|2002|pp=173–174}}

===''Prima causa'' (first cause)===
Thomas's five proofs for the existence of God take some of Aristotle's assertions concerning the principles of being. For God as ''[[prima causa]]'' ("first cause") comes from Aristotle's concept of the [[unmoved mover]] and asserts that God is the ultimate cause of all things.{{sfn|Nichols|2002|pp=80–82}}

===Nature of Jesus Christ===
[[File:Bartolomé Esteban Murillo Santo Tomás de Aquino.jpg|thumb|left|''Thomas Aquinas'' by [[Bartolomé Esteban Murillo]], 1650]]

In the ''Summa Theologica,'' Thomas begins his discussion of Jesus Christ by recounting the biblical story of [[Adam and Eve]] and by describing the negative effects of [[original sin]]. The purpose of Christ's Incarnation was to restore human nature by removing ''the contamination of sin'', which humans cannot do by themselves. "Divine Wisdom judged it fitting that God should become man, so that thus one and the same person would be able both to restore man and to offer satisfaction."<ref>Thomas Aquinas, pp. 228–229.</ref> Thomas argued in favour of the [[atonement (satisfaction view)|satisfaction view of atonement]]; that is, that [[Christian views of Jesus|Jesus Christ]] [[death of Jesus|died]] "to satisfy for the whole human race, which was sentenced to die on account of sin."<ref>{{Cite book |author=Thomas Aquinas |title=Summa Theologica |volume=III |chapter=Question 50, Article 1 |access-date=17 January 2010 |chapter-url=http://www.newadvent.org/summa/4050.htm#article1 |via=newadvent.org}}</ref>

Thomas argued against several specific contemporary and historical theologians who held differing views about Christ. In response to [[Photinus]], Thomas stated that Jesus was truly divine and not simply a human being. Against [[Nestorius]], who suggested that the Son of God was merely conjoined to the man Christ, Thomas argued that the fullness of God was an integral part of Christ's existence. However, countering [[Apollinaris of Laodicea|Apollinaris]]' views, Thomas held that Christ had a truly human (rational) [[soul]], as well. This produced a duality of nature in Christ. Thomas argued against [[Eutyches]] that this duality persisted after the Incarnation. Thomas stated that these two natures existed simultaneously yet distinguishably in one real human body, unlike the teachings of [[Manichaeus]] and [[Valentinus (Gnostic)|Valentinus]].<ref>Thomas Aquinas, pp. 231–239.</ref>

With respect to [[Paul the Apostle|Paul]]'s assertion that Christ, "though he was in the form of God{{nbsp}}... emptied himself" ([[Philippians]] 2:6–7) in becoming human, Thomas offered an articulation of divine [[kenosis]] that has informed much subsequent Catholic [[Christology]]. Following the [[First Council of Nicaea|Council of Nicaea]], [[Augustine of Hippo]], as well as the assertions of Scripture, Thomas held the doctrine of [[Immutability (theology)|divine immutability]].<ref>{{cite web |date=20 May 325 |title=First Council of Nicaea – 325 AD |url=https://www.papalencyclicals.net/councils/ecum01.htm |via=papalencyclicals.net}}</ref><ref>Augustine, Sermo VII, 7.</ref><ref>For instance, Malachi 3:6 and James 1:17</ref> Hence, in becoming human, there could be no change in the divine person of Christ. For Thomas, "the mystery of Incarnation was not completed through God being changed in any way from the state in which He had been from eternity, but through His having united Himself to the creature in a new way, or rather through having united it to Himself."<ref>ST III.1.1.</ref>

Similarly, Thomas explained that Christ "emptied Himself, not by putting off His divine nature, but by assuming a human nature."<ref name="dhspriory.org">{{cite web |title=Commentary on Saint Paul's Letter to the Philippians, available at §2–2. |url=http://dhspriory.org/thomas/english/SSPhilippians.htm |url-status=dead |archive-url=https://web.archive.org/web/20171020002518/http://dhspriory.org/thomas/english/SSPhilippians.htm |archive-date=20 October 2017 |access-date=19 June 2015}}</ref> For Thomas, "the divine nature is sufficiently full, because every perfection of goodness is there. But human nature and the soul are not full, but capable of fulness, because it was made as a slate not written upon. Therefore, human nature is empty."<ref name="dhspriory.org" /> Thus, when Paul indicates that Christ "emptied himself" this is to be understood in light of his assumption of a human nature.

In short, "Christ had a ''real body'' of the same nature of ours, a ''true rational soul'', and, together with these, ''perfect Deity''". Thus, there is both unity (in his one ''[[hypostasis (philosophy)|hypostasis]]'') and composition (in his two natures, human and Divine) in Christ.<ref>Thomas Aquinas, pp. 241, 245–249. Emphasis is the author's.</ref>

{{blockquote|I answer that, The Person or hypostasis of Christ may be viewed in two ways. First as it is in itself, and thus it is altogether simple, even as the Nature of the Word. Secondly, in the aspect of person or hypostasis to which it belongs to subsist in a nature; and thus the Person of Christ subsists in two natures. Hence though there is one subsisting being in Him, yet there are different aspects of subsistence, and hence He is said to be a composite person, insomuch as one being subsists in two.<ref>{{Cite book |chapter-url=http://www.newadvent.org/summa/4002.htm#article4 | author= Thomas Aquinas| title= Summa Theologica | chapter= The mode of union of the Word incarnate (Tertia Pars, Q. 2) | via= New Advent}}</ref>}}

Echoing [[Athanasius of Alexandria]], he said that "The only begotten Son of God{{nbsp}}... assumed our nature, so that he, made man, might make men gods."<ref>{{Cite book |last=Weigel |first=George |url=https://archive.org/details/truthofcatholici00weig/page/9 |title=The Truth of Catholicism |publisher=[[HarperCollins]] |year=2001 |isbn=0-06-621330-4 |location=New York |page=[https://archive.org/details/truthofcatholici00weig/page/9 9] |author-link=George Weigel}}</ref>

===Goal of human life===
[[File:Thomas von Aquin 17th century sculpture.jpeg|thumb|A 17th-century sculpture of Thomas Aquinas]]
Thomas Aquinas identified the goal of human existence as union and eternal fellowship with God. This goal is achieved through the [[beatific vision]], in which a person experiences perfect, unending happiness by seeing the essence of God. The vision occurs after death as a gift from God to those who in life experienced salvation and redemption through Christ.

The goal of union with God has implications for the individual's life on earth. Thomas stated that an individual's [[Free Will|will]] must be ordered toward the right things, such as charity, peace, and [[Sacred|holiness]]. He saw this orientation as also the way to happiness. Indeed, Thomas ordered his treatment of the moral life around the idea of happiness. The relationship between will and goal is antecedent in nature "because rectitude of the will consists in being duly ordered to the last end [that is, the beatific vision]." Those who truly seek to understand and see God will necessarily love what God loves. Such love requires morality and bears fruit in everyday human choices.{{sfn|Kreeft|1990|p=383}}

===Treatment of heretics===
Thomas Aquinas belonged to the Dominican Order (formally ''[[Ordo Praedicatorum]]'', the Order of Preachers) which began as an order dedicated to the conversion of the [[Albigensians]] and other heterodox factions, at first by peaceful means; later the Albigensians were dealt with by means of the [[Albigensian Crusade]]. In the ''Summa Theologiae'', he wrote:
<blockquote>With regard to heretics two points must be observed: one, on their own side; the other, on the side of the Church. On their own side there is the sin, whereby they deserve not only to be separated from the Church by excommunication, but also to be severed from the world by death. For it is a much graver matter to corrupt the faith that quickens the soul, than to forge money, which supports temporal life. Wherefore if forgers of money and other evil-doers are forthwith condemned to death by the secular authority, much more reason is there for heretics, as soon as they are convicted of heresy, to be not only excommunicated but even put to death.

On the part of the Church, however, there is mercy, which looks to the conversion of the wanderer, wherefore she condemns not at once, but "after the first and second admonition", as [[Paul of Tarsus|the Apostle]] directs: after that, if he is yet stubborn, the Church no longer hoping for his conversion, looks to the salvation of others, by excommunicating him and separating him from the Church, and furthermore delivers him to the secular tribunal to be exterminated thereby from the world by death.<ref>{{cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II–II |chapter=Question 11, Article 3 |chapter-url=http://www.newadvent.org/summa/3011.htm#article3}}</ref></blockquote>

Heresy was a capital offence against the secular law of most European countries of the 13th century. Kings and emperors, even those at war with the papacy, listed heresy first among the crimes against the state. Kings claimed power from God according to the Christian faith. Often enough, especially in that age of papal claims to universal worldly power, the rulers' power was tangibly and visibly legitimated directly through coronation by the pope.

Simple theft, forgery, fraud, and other such crimes were also capital offences; Thomas's point seems to be that the gravity of this offence, which touches not only the material goods but also the spiritual goods of others, is at least the same as forgery. Thomas's suggestion specifically demands that heretics be handed to a "secular tribunal" rather than [[magisterium|magisterial]] authority. That Thomas specifically says that heretics "deserve{{nbsp}}... death" is related to his theology, according to which all sinners have no intrinsic right to life ("For the wages of sin is death; but the free gift of God is eternal life in Christ Jesus our Lord"<ref>{{bibleverse|Romans|6:23|ASV}}</ref>). Although the life of a heretic who repents should be spared, the former heretic should be executed if he relapses into heresy. Thomas elaborates on his opinion regarding heresy in the next article, when he says:<blockquote>In God's tribunal, those who return are always received, because God is a searcher of hearts, and knows those who return in sincerity. But the Church cannot imitate God in this, for she presumes that those who relapse after being once received, are not sincere in their return; hence she does not debar them from the way of salvation, but neither does she protect them from the sentence of death.

For this reason the Church not only admits to Penance those who return from heresy for the first time, but also safeguards their lives, and sometimes by dispensation, restores them to the ecclesiastical dignities which they may have had before, should their conversion appear to be sincere: we read of this as having frequently been done for the good of peace. But when they fall again, after having been received, this seems to prove them to be inconstant in faith, wherefore when they return again, they are admitted to Penance, but are not delivered from the pain of death.<ref>{{cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II–II |chapter=Question 11, Article 4 |chapter-url=http://www.newadvent.org/summa/3011.htm#article4}}</ref></blockquote>

For Jews, Thomas argues for toleration of both their persons and their religious rites.<ref>Novak, Michael (December 1995), [http://www.firstthings.com/article/1995/12/003-aquinas-and-the-heretics "Aquinas and the Heretics"] {{Webarchive|url=https://web.archive.org/web/20160409052324/http://www.firstthings.com/article/1995/12/003-aquinas-and-the-heretics|date=9 April 2016}}, ''First Things''.</ref>

==== Forced baptism of children of Jews and heretics ====
The position taken by Thomas was that if children were being reared in error, the Church had no authority to intervene. From ''[[Summa Theologica]]'' II-II Q. 10 Art. 12:

: Injustice should be done to no man. Now it would be an injustice to Jews if their children were to be baptized against their will, since they would lose the rights of parental authority over their children as soon as these were Christians. Therefore, these should not be baptized against their parent's will. The custom of the Church has been given very great authority and ought to be jealously observed in all things, since the very doctrine of Catholic Doctors derives its authority from the Church. Hence we ought to abide by the authority of the Church rather than that of an [[Augustine of Hippo|Augustine]] or a [[Jerome]] or any doctor whatever. Now it was never the custom of the Church to baptize the children of Jews against the will of their parents. There are two reasons for this custom. One is on account of the danger to faith. For children baptized before coming into the use of reason, might easily be persuaded by their parents to renounce what they had unknowingly embraced; and this would be detrimental to the faith. The other reason is that it is against natural justice. For a child is by nature part of its father: at first, it is not distinct from its parents as to its body, so long as it is enfolded within the mother's womb and later on after birth, and before it has the use of [[free will]], it is enfolded in the care of its parents, like a spiritual womb. So long as a man does not have the use of reason, he is no different from an irrational animal. Hence, it would be contrary to natural justice, if a child, before coming to the use of reason, were to be taken away from its parent's custody, or anything done against its parent's wish.

The question was again addressed by Thomas in ''[[Summa Theologica]]'' III Q. 68 Art. 10:

: It is written in the Decretals (Dist. xiv), quoting the [[Council of Toledo]]: In regard to the Jews the holy synod commands that henceforth none of them be forced to believe; for such are not to be saved against their will, but willingly, that their righteousness may be without flaw. Children of non-believers either have the use of reason or they have not. If they have, then they already begin to control their own actions, in things that are of Divine or natural law. And therefore, of their own accord, and against the will of their parents, they can receive Baptism, just as they can contract in marriage. Consequently, such can be lawfully advised and persuaded to be baptized. If, however, they have not yet the use of free-will, according to the natural law they are under the care of their parents as long as they cannot look after themselves. For which reason we say that even the children of the ancients were saved through the faith of their parents.

The issue was discussed in a papal bull by [[Pope Benedict XIV]] (1747) where both schools were addressed. The pope noted that the position of Aquinas had been more widely held among theologians and [[canon lawyers]], than that of [[John Duns Scotus]].<ref>Denzinger, Henry, [[Enchiridion symbolorum, definitionum et declarationum de rebus fidei et morum|''The Sources of Catholic Dogma'']], B. Herder Book Company, St. Louis, Missouri, 1955, p.&nbsp;364.</ref>

===Magic and its practitioners===
Regarding magic, Thomas wrote that:
* only God can perform miracles, create and transform.<ref>''[[Summa contra gentiles]],'' p. 102.</ref>
* angels and demons ("spiritual substances") may do wonderful things, but they are not miracles and merely use natural things as instruments.<ref>''Summa contra gentiles,'' p. 103.</ref>
* any efficacy of magicians does not come from the power of particular words, or celestial bodies, or special figures, or sympathetic magic, but by bidding (ibid., 105)
* "demons" are intellective substances which were created good and have chosen to be bad, it is these who are bid.<ref>''Summa contra gentiles,'' pp. 106–108.</ref>
* if there is some transformation that could not occur in nature it is either the demon working on human imagination or arranging a fake.<ref>{{cite book |author=Thomas Aquinas |title=Summa Theologica |volume=I |chapter=Question 114, Article 4}}</ref>

A mention of witchcraft appears in the ''Summa Theologicae''<ref>{{cite book |title=Summa theologica Supplement |chapter=Question 38, Article 2 |quote=Whether a spell can be in impediment to marriage.}} Note this Supplement was written or compiled by others after Thomas's death.</ref> and concludes that the church does not treat temporary or permanent impotence attributed to a spell any differently to that of natural causes, as far as an impediment to marriage.

Under the ''[[canon Episcopi]]'', church doctrine held that witchcraft was not possible and any practitioners of sorcery were deluded and their acts an illusion. Thomas Aquinas was cited in a new doctrine that included the belief in witches. This was a departure from the teachings of his master [[Albertus Magnus]] whose doctrine was based in the ''Episcopi''.<ref name="Burr17374">{{cite book |last=Burr |first=G. L. |title=Selected Writings |year=1943 |editor=L. O. Gibbons |place=New York |pages=173–174}} Original essay (1890) available here [https://play.google.com/store/books/details?id=6ZUlAQAAMAAJ] {{Webarchive|url=https://web.archive.org/web/20210225085817/https://play.google.com/store/books/details?id=6ZUlAQAAMAAJ|date=25 February 2021}}.</ref> "To what extent Dominican inquisitors such as Heinrich Kramer really found support in Thomas is irrelevant in this context, thus associating Thomas's name with the whole aspect of witchcraft and the persecution of witches."<ref name=Haustein>{{Cite book|url=https://books.google.com/books?id=8ETPEAAAQBAJ&dq=Thomas+Aquinas+++witches&pg=PA54|title=Encyclopedia of Witchcraft: The Western Tradition [4 volumes]|first=Richard M. Golden Director, Jewish Studies|last=Program|date=30 January 2006|publisher=Bloomsbury Publishing USA|isbn=978-1-85109-512-4 |via=Google Books}}</ref>

The famous 15th-century witch-hunter's manual, the ''[[Malleus Maleficarum]]'', also written by a member of the Dominican Order, begins by quoting Thomas Aquinas ("Commentary on Pronouncements" Sent.4.34.I.Co.) refuting the ''Episcopi'' and goes on to cite Thomas Aquinas over a hundred times.<ref>{{cite book |last=Kramer |first=Heinrich |title=Malleus Maleficarum |year=2009 |place=Cambridge |pages=91–92 |translator=Christopher Mackay}}</ref> Promoters of the witch hunts that followed often quoted Thomas more than any other source.<ref name="Burr17374" /> "Thomas Aquinas's statements remain essentially theoretical and lack any direct relation to the subsequent persecution of witches."<ref name=Haustein/>

===Thoughts on the afterlife and resurrection===
[[File:Santo Tomás de Aquino - Antonio del Castillo Saavedra.jpg|thumb|Portrait of St. Thomas by [[Antonio del Castillo y Saavedra]], {{Circa|1649|lk=no}}]]
A grasp of Thomas's psychology is essential for understanding his beliefs about the afterlife and resurrection. Thomas, following church doctrine, accepts that the soul continues to exist after the death of the body. Because he accepts that the soul is the form of the body, then he also must believe that the human being, like all material things, is form-matter composite. The substantial form (the human soul) configures prime matter (the physical body) and is the form by which a material composite belongs to that species it does; in the case of human beings, that species is a rational animal.{{sfn|Stump|2003|p=194}} So, a human being is a matter-form composite that is organized to be a rational animal. Matter cannot exist without being configured by form, but form can exist without matter—which allows for the separation of soul from body. Thomas says that the soul shares in the material and spiritual worlds, and so has some features of matter and other, immaterial, features (such as access to universals). The human soul is different from other material and spiritual things; it is created by God, but also comes into existence only in the material body.

Human beings are material, but the human person can survive the death of the body through the continued existence of the soul, which persists. The human soul straddles the spiritual and material worlds, and is both a configured subsistent form as well as a configurer of matter into that of a living, bodily human.{{sfn|Stump|2003|p=200}} Because it is spiritual, the human soul does not depend on matter and may exist separately. Because the human being is a soul-matter composite, the body has a part in what it is to be human. Perfected human nature consists in the human dual nature, embodied and intellecting.

Resurrection appears to require dualism, which Thomas rejects. Yet Thomas believes the soul persists after the death and corruption of the body, and is capable of existence, separated from the body between the time of death and the [[resurrection of the flesh]]. Thomas believes in a different sort of dualism, one guided by Christian scripture. Thomas knows that human beings are essentially physical, but physicality has a spirit capable of returning to God after life.{{sfn|Stump|2003|p=192}} For Thomas, the rewards and punishment of the afterlife are not ''only'' spiritual. Because of this, resurrection is an important part of his philosophy on the soul. The human is fulfilled and complete in the body, so the hereafter must take place with souls enmattered in resurrected bodies. In addition to spiritual reward, humans can expect to enjoy material and physical blessings. Because Thomas's soul requires a body for its actions, during the afterlife, the soul will also be punished or rewarded in corporeal existence.

Thomas states clearly his stance on resurrection, and uses it to back up his philosophy of justice; that is, the promise of resurrection compensates Christians who suffered in this world through a heavenly union with the divine. He says, "If there is no resurrection of the dead, it follows that there is no good for human beings other than in this life."{{sfn|Stump|2003|pp=461, 473}} Resurrection provides the impetus for people on earth to give up pleasures in this life. Thomas believes the human who prepared for the afterlife both morally and intellectually will be rewarded more greatly; however, all reward is through the grace of God. Thomas insists beatitude will be conferred according to merit, and will render the person better able to conceive the divine.

Thomas accordingly believes punishment is directly related to earthly, living preparation and activity as well. Thomas's account of the soul focuses on epistemology and metaphysics, and because of this, he believes it gives a clear account of the immaterial nature of the soul. Thomas conservatively guards Christian doctrine and thus maintains physical and spiritual reward and punishment after death. By accepting the essentiality of both body and soul, he allows for a [[Heaven]] and [[Hell]] described in scripture and church [[dogma]].

==Philosophy==
{{Thomism}}
{{Main|Thomism}}
[[File:Friesach - Dominikanerkirche - Hochaltar - Hl Thomas von Aquin1.jpg|thumb|Thomas Aquinas and the Pope]]

Thomas Aquinas was a theologian and a [[Scholasticism|Scholastic]] philosopher.{{sfn|Jordan|2006|p=154}} He never considered himself a philosopher, and criticized philosophers whom he saw as pagans, for always "falling short of the true and proper wisdom to be found in Christian revelation".{{sfn|Davies|2004|p=14}} With this in mind, Thomas did have respect for Aristotle, so much so that in the ''Summa'', he often cites Aristotle simply as "the Philosopher", a designation frequently used at that time. However, Thomas "never compromised Christian doctrine by bringing it into line with current Aristotelianism; rather, he modified and corrected the latter whenever it clashed with Christian belief".<ref>{{Cite book |title=The History of Philosophy, Medieval Philosophy, from 500 to 1500 CE |publisher=Britannica Educational Publishing |year=2011 |isbn=978-1-61530-244-4 |editor=Duignan |editor-first=Brian |location=New York |chapter=Age of the Schoolmen}}</ref>

Much of Thomas's work bears upon philosophical topics, and in this sense may be characterized as philosophical. His philosophical thought has exerted enormous influence on subsequent Christian theology, especially that of the Catholic Church, extending to Western philosophy in general.

=== Commentaries on Aristotle ===
Thomas Aquinas wrote several important commentaries on [[Aristotle]]'s works, including ''[[On the Soul]]'', ''[[On Interpretation]]'', ''[[Posterior Analytics]]'', ''[[Nicomachean Ethics]]'', [[Physics (Aristotle)|''Physics'']] and ''[[Metaphysics (Aristotle)|Metaphysics]]''. His work is associated with [[William of Moerbeke]]'s translations of Aristotle from [[Ancient Greek|Greek]] into [[Latin]].

===Epistemology===
{{see also|Double truth}}

Thomas Aquinas believed "that for the knowledge of any truth whatsoever man needs divine help, that the intellect may be moved by God to its act."<ref>{{cite web |url=http://saints.sqpn.com/saint-thomas-aquinas/ |title=Blog Archive " Saint Thomas Aquinas |date=22 October 1974 |publisher=Saints.SQPN.com |access-date=17 January 2010}}</ref> However, he believed that human beings have the natural capacity to know many things without special [[divine revelation]], even though such revelation occurs from time to time, "especially in regard to such (truths) as pertain to faith."<ref name="Summa I-II Q109a1">{{cite web |url= http://ccel.org/ccel/aquinas/summa.FS_Q109_A1.html#FS_Q109_A1-p9 |title=''Summa'', I–II, Q109a1 |via =ccel.org |access-date=25 March 2012}}</ref> But this is the light that is given to man by God according to man's nature: "Now every form bestowed on created things by God has power for a determined act[uality], which it can bring about in proportion to its own proper endowment; and beyond which it is powerless, except by a superadded form, as water can only heat when heated by the fire. And thus the human understanding has a form, viz. intelligible light, which of itself is sufficient for knowing certain intelligible things, viz. those we can come to know through the senses."<ref name="Summa I-II Q109a1" />

===Ethics===
{{see also|Christian ethics}}
{{Redirect|Eternal law|2012 fantasy drama series|Eternal Law}}
Thomas was aware that the Albigensians and the Waldensians challenged moral precepts concerning marriage and ownership of private property and that challenges could ultimately be resolved only by logical arguments based on self-evident norms. He accordingly argued, in the Summa Theologiae, that just as the [[first principle]] of demonstration is the self-evident principle of noncontradiction ("the same thing cannot be affirmed and denied at the same time"), the first principle of action is the self-evident ''Bonum'' precept ("good is to be done and pursued and evil avoided").<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica, I-II q. 94, a. 2c |publisher= |url=https://www.newadvent.org/summa/2094.htm}}</ref>

This natural law precept prescribes doing and pursuing what reason knows is good while avoiding evil. Reason knows what is objectively good because good is naturally beneficial and evil is the contrary. To explain goods that are naturally self-evident, Thomas divides them into three categories: substantial goods of self-preservation desired by all; the goods common to both animals and humans, such as procreation and education of offspring; and goods characteristic of rational and intellectual beings, such as living in community and pursuing the truth about God.<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica I-II q. 94, a. 2.}}</ref>

To will such natural goods to oneself and to others is to love. Accordingly, Thomas states that the love precept obligating loving God and neighbour are "the first general principles of the natural law, and are self-evident to human reason, either through nature or through faith. Wherefore all the precepts of the decalogue are referred to these, as conclusions to general principles."<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica I-II q. 100, a. 3 ad 1.}}</ref><ref>{{Cite journal |last=Lemmons |first=R. Mary Hayden |date=1992 |title="Are the Love Precepts Really Natural Law's Primary Precepts?" |url=https://www.pdcnet.org/acpaproc/Proceedings-of-the-American-Catholic-Philosophical-Association |journal=Proceedings of the American Catholic Philosophical Association |volume=LXVI |pages=45–71 |doi=10.5840/acpaproc1992661 |via=Philosophy Documentation Center}}</ref>

To so focus on lovingly willing good is to focus natural law on acting virtuously. In his ''Summa Theologiae'', Thomas wrote:

{{blockquote|Virtue denotes a certain perfection of a power. Now a thing's perfection is considered chiefly in regard to its end. But the end of power is act. Wherefore power is said to be perfect, according as it is determinate to its act.<ref>{{Cite book |chapter-url= http://ccel.org/ccel/aquinas/summa.FS_Q55_A1.html#FS_Q55_A1-p8 | author= Thomas Aquinas| title= Summa Theologica | chapter= Question 55, Reply 1 |via= ccel.org |access-date=2012-02-02}}</ref>}}

Thomas emphasized that "[[Synderesis]] is said to be the law of our mind, because it is a habit containing the precepts of the natural law, which are the first principles of human actions."<ref name=SEP4 /><ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica| volume= First Part of the Second Part| chapter= Question 94, Reply Obj. 2}}</ref>

According to Thomas "...{{nbsp}}all acts of virtue are prescribed by the natural law: since each one's reason naturally dictates to him to act virtuously. But if we speak of virtuous acts, considered in themselves, i.e., in their proper species, thus not all virtuous acts are prescribed by the natural law: for many things are done virtuously, to which nature does not incline at first; but that, through the inquiry of reason, have been found by men to be conducive to well living." Therefore, we must determine if we are speaking of virtuous acts as under the aspect of virtuous or as an act in its species.<ref name="Thomas Aquinas">{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 3}}</ref>

Thomas defined the four [[cardinal virtues]] as [[prudence]], [[temperance (virtue)|temperance]], [[justice]], and [[courage|fortitude]]. The cardinal virtues are natural and revealed in nature, and they are binding on everyone. There are, however, three [[theological virtues]]: [[faith]], [[hope]], and [[charity (virtue)|charity]]. Thomas also describes the virtues as imperfect (incomplete) and perfect (complete) virtues. A perfect virtue is any virtue with charity, charity completes a cardinal virtue. A non-Christian can display courage, but it would be courage with temperance. A Christian would display courage with charity. These are somewhat supernatural and are distinct from other virtues in their object, namely, God:

{{blockquote|Now the object of the theological virtues is God Himself, Who is the last end of all, as surpassing the knowledge of our reason. On the other hand, the object of the intellectual and moral virtues is something comprehensible to human reason. Therefore the theological virtues are specifically distinct from the moral and intellectual virtues.<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 62, Article 2| chapter-url=http://ccel.org/ccel/aquinas/summa.FS_Q62_A2.html#FS_Q62_A2-p6 | via= ccel.org |access-date=2012-02-02}}</ref>}}

Thomas Aquinas wrote "[Greed] is a sin against God, just as all mortal sins, in as much as man condemns things eternal for the sake of temporal things."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | volume= Second Part of the Second Part| chapter= Question 118, Article 1 |chapter-url= http://www.ccel.org/a/aquinas/summa/SS/SS118.html#SSQ118A1THEP1 |via= ccel.org| access-date= 26 October 2018}}</ref>

Furthermore, in his ''[[Treatise on Law]]'', Thomas distinguished four kinds of law: eternal, [[Natural law|natural]], human, and [[Divine law|divine]]. ''Eternal law'' is the decree of God that governs all creation: "That Law which is the Supreme Reason cannot be understood to be otherwise than unchangeable and eternal."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 91, Article 1}}</ref> ''Natural law'' is the human "participation" in the ''eternal law'' and is discovered by [[reason]].<ref>{{Cite book |url=https://archive.org/details/ethics00loui |title=Ethics: Discovering Right and Wrong |last=Pojman |first=Louis |publisher=Wadsworth Publishing Company |year=1995 |isbn=0-534-56138-1 |location=Belmont, California |author-link=Louis Pojman}}</ref> ''Natural law'' is based on "[[first principles]]":

{{blockquote|. . . this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this . . .<ref>{{Cite book |chapter-url= http://ccel.org/ccel/aquinas/summa.FS_Q94_A2.html#FS_Q94_A2-p7 | author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 2 |via= ccel.org |access-date=2012-02-02}}</ref>}}

Whether the natural law contains several precepts, or one only is explained by Thomas, "All the inclinations of any parts whatsoever of human nature, e.g., of the concupiscible and irascible parts, in so far as they are ruled by reason, belong to the natural law, and are reduced to one first precept, as stated above: so that the precepts of the natural law are many in themselves, but are based on one common foundation."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Second Article, Reply Obj. 2}}</ref>

[[File:Tommaso Aquino - Francisco de Zurbarán.jpg|thumb|upright=.7|Detail of ''[[The Apotheosis of Saint Thomas Aquinas]]'' by [[Francisco de Zurbarán]], 1631]]
The desires to live and to procreate are counted by Thomas among those basic (natural) human values on which all human values are based. According to Thomas, all human tendencies are geared towards real human goods. In this case, the human nature in question is marriage, the total gift of oneself to another that ensures a family for children and a future for mankind.<ref>{{Cite book |chapter-url= http://www.corpusthomisticum.org/snp4027.html |volume= IV, Commentary| title=In Sententiae |chapter= d. 27 q. 1 a.1 |last=Aquinas |first=Thomas |via= corpusthomisticum.org |access-date=21 September 2011}}</ref> He defined the dual inclination of the action of love: "towards the good which a man wishes to someone (to himself or to another) and towards that to which he wishes some good".<ref name="newadvent.org">{{Cite book |chapter-url=http://www.newadvent.org/summa/2026.htm#article4 | author= Thomas Aquinas| title= Summa Theologica | chapter= STh I–II, 26, 4, corp. art |via= New Advent |access-date=30 October 2010}}</ref>

Concerning Human Law, Thomas concludes, "...{{nbsp}}that just as, in the speculative reason, from naturally known indemonstrable principles, we draw the conclusions of the various sciences, the knowledge of which is not imparted to us by nature, but acquired by the efforts of reason, so to it is from the precepts of the natural law, as from general and indemonstrable principles, that human reason needs to proceed to the more particular determination of certain matters. These particular determinations, devised by human reason, are called human laws, provided the other essential conditions of law be observed{{nbsp}}..." Human law is [[positive law]]: the natural law applied by governments to societies.<ref name="Thomas Aquinas"/>

Natural and human law is not adequate alone. The need for human behaviour to be directed made it necessary to have Divine law. Divine law is the specially revealed law in the [[scriptures]]. Thomas quotes, "The Apostle says (Hebrews 7.12): The priesthood being translated, it is necessary that a translation also be made of the law. But the priesthood is twofold, as stated in the same passage, viz, the levitical priesthood, and the priesthood of Christ. Therefore, the Divine law is twofold, namely, the Old Law and the New Law."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 5}}</ref>

Thomas also greatly influenced Catholic understandings of [[mortal sin|mortal]] and [[venial sin]]s.

Thomas Aquinas refers to animals as dumb and that the natural order has declared animals for man's use. Thomas denied that human beings have any duty of charity to animals because they are not persons. Otherwise, it would be unlawful to kill them for food. But humans should still be charitable to them, for "cruel habits might carry over into our treatment of human beings."<ref>{{Cite book |title=The Oxford Companion to Philosophy |year=1995 |editor-last=Honderich |editor-first=Ted |location=Oxford |pages=35–36 |chapter=Animals: Peter Singer |chapter-url=http://www.utilitarian.net/singer/by/1995----04.htm |via=utilitarian.net |access-date=30 November 2006 |archive-date=13 October 2009 |archive-url=http://arquivo.pt/wayback/20091013000816/http://www.utilitarian.net/singer/by/1995----04.htm |url-status=dead }}</ref><ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | volume= Second Part of the Second Part| chapter= Question 64. Article 1}}</ref>

Thomas contributed to [[History of economic thought#Economic thought in the Middle Ages (500–1500 AD)|economic thought]] as an aspect of ethics and justice. He dealt with the concept of a [[just price]], normally its market price or a regulated price sufficient to cover seller [[costs of production]]. He argued it was immoral for sellers to raise their prices simply because buyers were in pressing need of a product.<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter-url= http://www.saylor.org/site/wp-content/uploads/2012/06/ECON301-2.1.2-1st.pdf |chapter= Of Cheating, Which Is Committed in Buying and Selling| translator= The Fathers of the English Dominican Province| access-date= 19 June 2012}}</ref><ref>{{Cite book |last=Gordon |first=Barry |title=The New Palgrave: A Dictionary of Economics |title-link=The New Palgrave: A Dictionary of Economics |year=2009 |volume=1 |page=100 |chapter=Aquinas, St. Thomas (1225–1274) |orig-year=1987}}</ref>

===Political order===
Thomas's theory of political order became highly influential. He sees man as a social being who lives in a community and interacts with its other members. That leads, among other things, to the [[division of labour]].

Thomas made a distinction between a good man and a good citizen, which was important to the development of [[libertarian]] theory. That indicates, in the eyes of the atheist libertarian writer [[George H. Smith]], that the sphere of [[individual autonomy]] was one which the state could not interfere with.{{sfn|Smith |2008|p=18}}

Thomas thought that monarchy was the best form of government because a monarch does not have to form compromises with other persons. Thomas, however, held that monarchy in only a very specific sense was the best form of government—only when the king was virtuous is it the best form; otherwise if the monarch is vicious it is the worst kind (see De Regno I, Ch. 2). Moreover, according to Thomas, [[oligarchy]] degenerates more easily into [[tyranny]] than monarchy. To prevent a king from becoming a tyrant, his political powers must be curbed. Unless an agreement of all persons involved can be reached, a tyrant must be tolerated, as otherwise, the political situation could deteriorate into anarchy, which would be even worse than tyranny. In his political work ''[[List of works by Thomas Aquinas#De Regno, to the King of Cyprus|De Regno]]'', Thomas subordinated the political power of the king to the primacy of the divine and human law of [[Creator deity#Christianity|God the creator]]. For example, he affirmed:
{{blockquote|Just as the government of a king is the best, so the government of a tyrant is the worst.|{{cite web|url=https://isidore.co/aquinas/DeRegno.htm#4|title=''De Regno'', Ch. 4, n. 21|language=Latin, English}}}}
{{blockquote|It is plain, therefore, from what has been said, that a king is one who rules the people of one city or province, and rules them for the common good.|{{cite web|url=https://isidore.co/aquinas/DeRegno.htm#2|title=''De Regno'', Ch. 2, n. 15|language=Latin, English}}}}

According to Thomas, monarchs are God's representatives in their territories, but the church, represented by the popes, is above the kings in matters of doctrine and ethics. As a consequence, worldly rulers are obliged to adapt their laws to the Catholic Church's doctrines and determinations.

Thomas said slavery was not the natural state of man.<ref>Weithman, Paul J. (1992). [https://www3.nd.edu/~pweithma/My%20Papers/Augustine%20and%20Aquinas%20on%20Political%20Authority.pdf "Augustine and Aquinas on Original Sin and the Function of Political Authority"] {{Webarchive|url=https://web.archive.org/web/20211209001913/https://www3.nd.edu/~pweithma/My%20Papers/Augustine%20and%20Aquinas%20on%20Political%20Authority.pdf |date=9 December 2021 }}, p. 356.</ref> He also held that a slave is by nature equal to his master (''Summa Theologiae Supplement'', Q52, A2, ad 1). He distinguished between 'natural slavery', which is for the benefit of both master and slave, and 'servile slavery', which removes all autonomy from the slave and is, according to Thomas, worse than death.<ref>{{cite web |url=http://ldysinger.stjohnsem.edu/@texts2/1271_aquinas/08_aq_slavery-ST3.htm |title=Aquinas on Slavery |website=stjohnsem.edu |access-date=26 November 2019 |archive-date=5 January 2021 |archive-url=https://web.archive.org/web/20210105224611/http://ldysinger.stjohnsem.edu/@texts2/1271_aquinas/08_aq_slavery-ST3.htm |url-status=dead }}</ref> Aquinas' doctrines of the Fair Price,<ref>{{cite journal|author1=Nureev Rustem, M.|title=Doctrine of "Fair Price" by Thomas Aquinas: background, laws of development and specific interpretation|journal=Journal of Institutional Studies|issue=1|volume=7|date=1 March 2015|pages=6–24|doi=10.17835/2076-6297.2015.7.1.006-024|issn= 2076-6297|oclc= 8773558345|doi-access=free}}</ref> of the right of [[tyrannicide]] and of the equality of all the baptized sons of God in the [[Communion of saints]] established a limit to the political power to prevent it from degenerating into tyranny. This system had a concern in the Protestant opposition to the Catholic Church and in "disinterested" replies to Thomism carried out by [[Immanuel Kant|Kant]] and by [[Baruch Spinoza|Spinoza]].

==== Death penalty ====
In [[Summa Contra Gentiles]], Book 3, Chapter 146, which was written by Thomas prior to writing the [[Summa Theologica]], Thomas allowed the judicial death penalty. He stated:<ref>Summa Conta Gentiles, Book III, Chapter 146, paragraphs 2–5, https://isidore.co/aquinas/ContraGentiles3b.htm#146. {{Webarchive|url=https://web.archive.org/web/20221030102342/https://isidore.co/aquinas/ContraGentiles3b.htm#146|date=30 October 2022}}.</ref>

{{Blockquote|[M]en who are in authority over others do no wrong when they reward the good and punish the evil.

[…] for the preservation of concord among men it is necessary that punishments be inflicted on the wicked. Therefore, to punish the wicked is not in itself evil.

Moreover, the common good is better than the particular good of one person. So, the particular good should be removed in order to preserve the common good. But the life of certain pestiferous men is an impediment to the common good which is the concord of human society. Therefore, certain men must be removed by death from the society of men.

Furthermore, just as a physician looks to health as the end in his work, and health consists in the orderly concord of humors, so, too, the ruler of a state intends peace in his work, and peace consists in "the ordered concord of citizens." Now, the physician quite properly and beneficially cuts off a diseased organ if the corruption of the body is threatened because of it. Therefore, the ruler of a state executes pestiferous men justly and sinlessly in order that the peace of the state may not be disrupted.}}

However, in the same discussion:
{{Blockquote| The unjust execution of men is prohibited…Killing which results from anger is prohibited…The execution of the wicked is forbidden wherever cannot be done without danger to the good. }}

===Just war===
{{See also|Just War}}

While it would be contradictory to speak of a "just schism", a "just brawling" or a "just sedition", the word "war" permits sub-classification into good and bad kinds. Thomas Aquinas, centuries after [[Augustine of Hippo]], used the authority of Augustine's arguments in an attempt to define the conditions under which a war could be [[Just war theory|just]].<ref>{{Cite web |title=The Just War |url=http://www.catholiceducation.org/articles/politics/pg0029.html |url-status=live |archive-url=https://web.archive.org/web/20210423100800/https://www.catholiceducation.org/articles/politics/pg0029.html |archive-date=23 April 2021 |access-date=24 February 2012}}</ref> He laid these out in his work ''[[Summa Theologica]]'':
* First, war must occur for a good and just purpose rather than the pursuit of wealth or power.
* Second, just war must be waged by a properly instituted authority such as the state.
* Third, peace must be a central motive even in the midst of violence.<ref>{{Cite book |last=Gonzalez |first=Justo L. |url=https://archive.org/details/storyofchristian01gonz |title=The Story of Christianity |publisher=HarperSanFrancisco |year=1984 |url-access=registration}}</ref>

===Psychology and anthropology===
Thomas Aquinas maintains that a human is a single material substance. He understands the soul as the form of the body, which makes a human being the composite of the two. Thus, only living, form-matter composites can truly be called human; dead bodies are "human" only analogously. One actually existing substance comes from body and soul. A human is a single material substance, but still should be understood as having an immaterial soul, which continues after bodily death.

In his ''Summa Theologiae'' Thomas states his position on the nature of the soul; defining it as "the first principle of life".<ref>{{Cite book |title=Summa Theologiae of St. Thomas Aquinas |last=Aquinas |first=Thomas |year=1920 |edition=Second and Revised |translator-last=The Fathers of the English Dominican Province |chapter=Question 75, Article 1}}</ref> The soul is not corporeal, or a body; it is the act of a body. Because the intellect is incorporeal, it does not use the bodily organs, as "the operation of anything follows the mode of its being".<ref>{{Cite book |title=Summa Theologiae of St. Thomas Aquinas |last=Aquinas |first=Thomas |year=1920 |edition=Second and Revised |translator-last=The Fathers of the English Dominican Province |chapter=Question 75, Article 3}}</ref>

[[File:Luis muñoz-santo tomás de aquino.jpg|thumb|right|Saint Thomas Aquinas by Luis Muñoz Lafuente]]
According to Thomas, the soul is not matter, not even incorporeal or spiritual matter. If it were, it would not be able to understand universals, which are immaterial. A receiver receives things according to the receiver's own nature, so for the soul (receiver) to understand (receive) universals, it must have the same nature as universals. Yet, any substance that understands universals may not be a matter-form composite. So, humans have rational souls, which are abstract forms independent of the body. But a human being is one existing, single material substance that comes from body and soul: that is what Thomas means when he writes that "something one in nature can be formed from an intellectual substance and a body", and "a thing one in nature does not result from two permanent entities unless one has the character of substantial form and the other of matter."<ref>{{Cite book |title=Summa Contra Gentiles |last=Aquinas |first=Thomas |publisher=U. of Notre Dame Press |year=1975 |location=Notre Dame, Ind. |translator-last=Anton C. Pegis |chapter=5 volumes. |display-authors=etal}}</ref>

===Economics===
Thomas Aquinas addressed most economic questions within the framework of justice, which he contended was the highest of the moral virtues.<ref>{{Cite web |url=https://www.newadvent.org/summa/2066.htm#article4 |title=''Summa Theologica'', Question 64, Article 4, "Whether justice is the chief of the moral virtues?" |access-date=29 May 2020 |archive-date=19 April 2021 |archive-url=https://web.archive.org/web/20210419033704/https://www.newadvent.org/summa/2066.htm#article4 |url-status=live }}</ref> He says that justice is "a habit whereby man renders to each his due by a constant and perpetual will."<ref>{{Cite book |title=Summa Theologica |last=Aquinas |first=Thomas |publisher=English Dominican Fathers |year=1981 |location=New York |pages=II-II, Q58, A1}}</ref> He argued that this concept of justice has its roots in natural law. Joseph Schumpeter, in his ''History of Economic Analysis'', concluded that "All the economic questions put together matters less to him than did the smallest point of theological or philosophical doctrine, and it is only where economic phenomena raise questions of moral theology that he touches upon them at all."<ref>{{Cite book |title=History of Economic Analysis |last=Schumpeter |first=Joseph |publisher=Oxford University Press |year=1954 |location=New York |page=90}}</ref>

Modern Western views concerning [[capitalism]], [[unfair labor practice]], [[living wage]], [[price gouging]], monopolies, fair trade practices, and [[predatory pricing]], inter alia, are remnants of the inculcation of Aquinas' interpretation of natural moral law.<ref>[[Marcia Colish|Colish, Marcia]], ''Medieval Foundations of the Western Intellectual Tradition, 400–1400'', Yale University Press, 1997, pp. 333–334.</ref>

====Just price====
Thomas Aquinas distinguished the [[Just price|just]], or natural, price of a good from that price which manipulates another party. He determines the just price from a number of things. First, the just price must be relative to the worth of the good. Thomas held that the price of a good measures its quality: "the quality of a thing that comes into human use is measured by the price given for it".<ref>{{Cite book |title=Summa Theologica |last=Aquinas |first=Thomas |publisher=English Dominican Fathers |year=1981 |location=New York |pages=II-II, Q77, A1}}</ref> The price of a good, measured by its worth, is determined by its usefulness to man. This worth is subjective because each good has a different level of usefulness to every man. The price should reflect the current value of a good according to its usefulness to man. "Gold and silver are costly not only on account of the usefulness of the vessels and other like things made from them, but also on account of the excellence and purity of their substance."<ref>{{Cite book |title=Summa Theologica |last=Aquinas |first=Thomas |publisher=English Dominican Fathers |year=1981 |location=New York |pages=II-II, Q77, A2}}</ref>

==== Social justice ====
{{Integralism |expanded=people}}
Thomas defines [[distributive justice]] as follows:<ref>{{Cite web |title=Summa Theologiae: The parts of Justice (Secunda Secundae Partis, Q. 61) |url=https://www.newadvent.org/summa/3061.htm |access-date=30 August 2022 |website=www.newadvent.org}}</ref><blockquote>[I]n distributive justice something is given to a private individual, in so far as what belongs to the whole is due to the part, and in a quantity that is proportionate to the importance of the position of that part in respect of the whole. Consequently, in distributive justice a person receives all the more of the common goods, according as he holds a more prominent position in the community. This prominence in an aristocratic community is gauged according to virtue, in an oligarchy according to wealth, in a democracy according to liberty, and in various ways according to various forms of community. Hence in distributive justice the mean is observed, not according to equality between thing and thing, but according to proportion between things and persons: in such a way that even as one person surpasses another, so that which is given to one person surpasses that which is allotted to another.</blockquote>Thomas asserts that Christians have a duty to distribute with provision to the poorest of society.<ref>Gilson, Etienne, ''The Christian Philosophy of St. Thomas Aquinas'', University of Notre Dame Press, 1994.</ref>

"[[Social justice]]" is a term that arose in the 19th century in the writings of Luigi Taparelli,<ref>{{Cite web |date=8 October 2014 |title=The Origins of Social Justice: Taparelli d'Azeglio |url=https://isi.org/intercollegiate-review/the-origins-of-social-justice-taparelli-dazeglio/}}</ref> and it was his term for the reality Thomas Aquinas called "legal justice" or "general justice". Legal or social justice is the contribution of the individual to the common good. So for Thomas, distributive justice goes in the direction from the [[common good]] to the individual, and is a proportional distribution of common goods, to individuals based on their contribution to the community. Legal or general justice, or what came to be called social justice, goes in the other direction, from the individuals to the common good.<ref>{{Cite web|url=https://aquinas.cc/la/en/~Eth.Bk5|title=Aquinas|website=aquinas.cc}}</ref>

It is helpful to understand as well other related types of justice: if social justice is from the individual to the community, and distributive justice is from the community to the individual, there is also commutative justice (between two individuals, as in buying and selling, or stealing and returning) as well as retributive justice (rectifications that occur to restore justice, once justice has been violated).<ref>{{Cite web|url=https://aquinas.cc/la/en/~ST.II-II.Q61|title=Aquinas|website=aquinas.cc}}</ref><ref>{{Cite web|url=https://www.newadvent.org/summa/3061.htm|title=SUMMA THEOLOGIAE: The parts of Justice (Secunda Secundae Partis, Q. 61)|website=www.newadvent.org}}</ref>

==== Usury ====
The [[Second Lateran Council]] called the practice of loaning money "detestable and shameful... insatiable rapacity of money lenders, forbidden both by divine and human laws throughout the Old and New Testament, we condemn, and separate from the ecclesiastical consolation".<ref>{{Cite web |title=Denzinger EN 712 |url=http://www.clerus.org/bibliaclerusonline/en/dwy.htm |access-date=30 August 2022 |website=www.clerus.org}}</ref> The [[Fifth Lateran Council]] defined [[usury]] as "when, from its use, a thing which produces nothing is applied to the acquiring of gain and profit without any work, any expense or any risk".<ref>{{Cite web |title=The Red Herring of Usury |url=https://www.catholic.com/magazine/print-edition/the-red-herring-of-usury |access-date=30 August 2022 |website=Catholic Answers|last1=Palm|first1=David J. }}</ref>

Thomas Aquinas also wrote extensively on [[usury]], that is, the lending of money with interest. He condemned its practice: "to take usury for money lent is unjust in itself, because this is to sell what does not exist, and this evidently leads to inequality which is contrary to justice".<ref>{{Cite book |title=Summa Theologica |author=Thomas Aquinas |publisher=English Dominican Fathers |year=1981 |location=New York |pages=II-II, Q78, A1}}</ref> Money, and other similar goods, are consumed only when they are used. Charging a premium for money lent is a charge for ''more'' than the use of the good. Thus, Thomas Aquinas concluded that the lender is charging for something not his own, in other words, not rendering to each his due.

==Works==
{{main|List of works by Thomas Aquinas}}

Although he died before his fiftieth birthday, and was only writing actively for about two decades, Thomas managed to write over eight million words.<ref>{{Citation |last=Pasnau |first=Robert |title=Thomas Aquinas |date=2024 |editor-last=Zalta |editor-first=Edward N. |url=https://plato.stanford.edu/archives/sum2024/entries/aquinas/ |access-date=2024-07-27 |edition=Summer 2024 |publisher=Metaphysics Research Lab, Stanford University |editor2-last=Nodelman |editor2-first=Uri |encyclopedia=The Stanford Encyclopedia of Philosophy}}.</ref> Thomas's systematic works, particularly the ''Summa Theologiae'', are his best-known, but collections of his complete works are dozens of volumes long. His works can be grouped into six categories:

# Works written in direct connection to his teaching, including seven systematic disputations and twelve [[quodlibeta]]l collections.
# Philosophical commentaries – eleven on Aristotle, and two each on Boethius and [[Proclus]].
# Lesser tracts, including polemic writings, letters, expert opinions, homilies, and his "catena aurea" collection of glosses on the Gospels.
# His systemic works: the ''Summa Theologiae'', ''Summa contra Gentiles'', and his commentary on Peter Lombard's ''Sentences''.
# His biblical commentaries.
# His liturgical works.

The first edition of Thomas's [[The Complete Works|complete works]], the so-called ''editio Piana'' (from [[Pius V]], the Pope who commissioned it), was produced in 1570 at the ''studium'' of the Roman convent at [[Santa Maria sopra Minerva]], the forerunner of the [[Pontifical University of Saint Thomas Aquinas|Pontifical University of Saint Thomas Aquinas, ''Angelicum'']].{{sfn|Renz|2009|p=42}}

The critical edition of Thomas's works is the ongoing edition commissioned by [[Pope Leo XIII]] (1882–1903) under the title ''Sancti Thomae Aquinatis Doctoris Angelica Opera Omnia'', the so-called [[Leonine Edition]]. Most of his major works have now been edited for the Leonine Edition. They include Thomas's commentaries on Aristotle's ''On Interpretation'' (''Peri hermeneias'') and ''[[Posterior Analytics]]'' (''Posteriorum analyticorum''), prepared by Thomas Maria Zigliara, in the first volume (1882), the ''Summa Theologiae'' in nine volumes from 1888 to 1906, and the ''Summa contra Gentiles'' in three volumes from 1918 to 1930.

[[Abbé Migne]] published an edition of the ''Summa Theologiae'', in four volumes, as an appendix to his ''[[Patrologiae Cursus Completus]]'' (English editions: [[Joseph Rickaby]] 1872, J. M. Ashley 1888).

Electronic texts of mostly the Leonine Edition are maintained online by the Corpus Thomisticum<ref>{{cite web |url= http://www.corpusthomisticum.org/ |title=Corpus Thomisticum |last=Alarcón |first=Enrique |date=4 December 2000 |website= corpusthomisticum.org}}</ref> by Enrique Alarcón, [[University of Navarra]], and at Documenta Catholica Omnia.<ref>{{cite web |url= http://www.documentacatholicaomnia.eu/20_50_1225-1274-_Thomas_Aquinas,_Sanctus.html |title=1225–1274 – Thomas Aquinas, Sanctus – Operum Omnium Conspectus seu 'Index of available Writings' |website= documentacatholicaomnia.eu}}</ref>

==See also==
{{div col|colwidth=20em}}
* ''[[Adoro te devote]]''
* [[Via eminentiae|Apophatic theology § The ''via eminentiae'']]
* [[Christian mysticism]]
* ''[[Corpus Domini]]''
* [[High Middle Ages]]
* ''[[Lauda Sion]]''
* [[Law of non-contradiction]]
* [[List of institutions named after Thomas Aquinas]]
* [[Medieval university]]
* [[Neo-Thomism]]
* [[Omnipotence paradox]]
* [[Rose of Viterbo]]
* ''[[Sacris solemniis]]''
* [[Portal:Catholic Church/Patron Archive/January 28|Saint Thomas Aquinas, patron saint archive]]
* [[Thomism]]
* [[Transubstantiation]]
* ''[[Verbum supernum prodiens]]''
{{div col end}}

===Thomists===
<!-- please keep entries in alphabetical order -->
{{div col|colwidth=20em}}
* [[J. Budziszewski]]
* [[Thomas Cajetan]]
* [[John Capreolus]]
* [[Frederick Copleston]]{{sfn|Copleston|1955|p=}}
* [[Brian Davies (philosopher)]]
* [[Charles De Koninck]]
* [[E.R. Fairweather]]
* [[Robert Alspaugh]]
* [[Reginald Garrigou-Lagrange]]
* [[G. K. Chesterton]]
* [[Étienne Gilson]]
* [[Alasdair MacIntyre]]
* [[Jacques Maritain]]
* [[Ralph McInerny]]
* [[Anton Charles Pegis|Anton Pegis]]
* [[Josef Pieper]]
* [[Santiago María Ramírez Ruíz de Dulanto]]
* [[James V. Schall]]
* [[Edward Feser]]
* [[Mieczysław Albert Krąpiec]]
* [[Pope John Paul II]]
* [[Pope Pius X]]
* [[Juan de Torquemada (cardinal)]]
{{div col end}}

==Notes==
{{notelist|refs=

{{efn|name=Pius XI|See Pius XI, ''Studiorum Ducem'' 11 (29 June 1923), AAS, XV ("non-modo Angelicum, sed etiam Communem seu Universalem Ecclesiae Doctorem"). The title {{lang|la|Doctor Communis}} dates to the fourteenth century; the title {{lang|la|Doctor Angelicus}} dates to the fifteenth century, see Walz, ''Xenia Thomistica'', III, p. 164 n. 4. [[Tolomeo da Lucca]] writes in ''Historia Ecclesiastica'' (1317): "This man is supreme among modern teachers of philosophy and theology, and indeed in every subject. And such is the common view and opinion, so that nowadays in the [[University of Paris]] they call him the {{lang|la|Doctor Communis}} because of the outstanding clarity of his teaching." ''Historia Eccles''. xxiii, c. 9.}}

{{efn|name=qualities|Thomas does not ascribe actual qualities to God Himself.}}

{{efn|name=objects|Even when we guide objects, in Thomas's view the source of all our knowledge comes from God as well.}}

}}

==References==
=== Citations ===
{{Reflist|22em|refs=

<ref name=diobeth>{{cite web |url=http://diobeth.typepad.com/files/holy-women-holy-men.pdf |title=Holy Men and Holy Women |website=Churchofengland.org}}</ref>

<ref name=resurrectionpeople.org>{{cite web |url=http://www.resurrectionpeople.org/saints.html |title=Notable Lutheran Saints |website=Resurrection Lutheran Church |access-date=16 July 2019 |archive-date=16 May 2019 |archive-url=https://web.archive.org/web/20190516024927/http://www.resurrectionpeople.org/saints.html |url-status=dead }}</ref>

<ref name=catholicsaints.info>{{cite web |url=http://catholicsaints.info/saint-thomas-aquinas/ |title=Saint Thomas Aquinas |date=12 December 2008 |website=CatholicSaints.Info  |access-date=20 January 2020}}</ref>

<!--(this citation is not used in content and was thus giving a cite error)
<ref name=iep.avicenna>{{cite web |url=http://www.iep.utm.edu/a/avicenna.htm#H5 |title=Avicenna (Ibn Sina) (c. 980–1037) |date=6 January 2006 |publisher=The Internet Encyclopedia of Philosophy |access-date=19 January 2010}}</ref-->

<!--(this citation is not used in content and was thus giving a cite error)
<ref name=iep.anselm>{{Citation |last=Sadler |first=Greg |title=Internet Encyclopedia of Philosophy |year=2006 |contribution=Anselm of Canterbury (1033–1109) |contribution-url=http://www.iep.utm.edu/anselm/ |ref={{harvid|''IEP''|2006}} |access-date=10 November 2017 |display-authors=0 |title-link=Internet Encyclopedia of Philosophy}}</ref-->

<ref name="SEP">{{cite encyclopedia |title=The Correspondence Theory of Truth |encyclopedia=Stanford Encyclopedia of Philosophy |date=Summer 2022 |last=David |first=Marian |publisher=Metaphysics Research Lab, Stanford University |url=https://plato.stanford.edu/archives/sum2022/entries/truth-correspondence/ |access-date=24 February 2023}}</ref>

<ref name=SEP2>{{cite encyclopedia| last1= McInerny| first1= Ralph |first2= John |last2= O'Callaghan| url= http://plato.stanford.edu/entries/aquinas/ |title= Saint Thomas Aquinas| encyclopedia= The Stanford Encyclopedia of Philosophy | year= 2018 |edition= Fall 2008| editor= Edward N. Zalta | via= stanford.edu}}</ref>

<ref name=SEP3>{{cite book |url=https://plato.stanford.edu/archives/sum2018/entries/aquinas/ |title=The Stanford Encyclopedia of Philosophy |last1=McInerny |first1=Ralph |last2=O'Callaghan |first2=John |chapter=Saint Thomas Aquinas |date=5 February 2018 |publisher=Metaphysics Research Lab, Stanford University |editor-last=Zalta |editor-first=Edward N. |via=Stanford Encyclopedia of Philosophy}}</ref>

<ref name=SEP4>{{Cite book |url= https://plato.stanford.edu/archives/fall2015/entries/conscience-medieval/ |title=The Stanford Encyclopedia of Philosophy |last= Langston |first= Douglas |date=5 February 2015 |publisher=Metaphysics Research Lab, [[Stanford University]] |editor-last=Zalta |editor-first=Edward N. |via=stanford.edu}}</ref>
}}

===Sources===
{{refbegin|30em|indent=yes}}
<!--A-->
* {{cite book |author=Anon. |title=The Irish Ecclesiastical Record |url=https://books.google.com/books?id=fpYvAAAAYAAJ&pg=PA570 |series=Year 32 |volume=V, No. 37 |year=1899 |publisher=Browne and Nolan}}
<!--B-->
<!--C-->
* {{Cite book |url=https://archive.org/details/saintthomasaquin00conwuoft |title=Saint Thomas Aquinas |last=Conway |first=John Placid |year=1911 |location=London, England}}
* {{cite book |last=Copleston |first=Frederick C. |author-link=Frederick Copleston |date=1955 |title=Aquinas |url=https://books.google.com/books?id=07AS-8aoEXQC |publisher=Penguin |isbn=978-0140136746}}
<!--D-->
* {{Cite book |title=The Thought of Thomas Aquinas |last=Davies |first=Brian |publisher=Oxford University Press |year=1993 |isbn=0-19-826753-3}}
* {{Cite book |title=Aquinas: An Introduction |last=Davies |first=Brian |publisher=Continuum |year=2004 |isbn=0-8264-7095-5 |author-mask={{long dash}}}}
* {{cite book |last1=de Tocco |first1=Guilelmus |last2=Le Brun-Gouanvic |first2=Claire |title=Ystoria sancti Thome de Aquino de Guillaume de Tocco (1323) |url=https://books.google.com/books?id=iuDhWSLoah8C |year=1996 |publisher=Pontifical Institute of Mediaeval Studies |isbn=978-0-88844-127-0}}
<!-- G -->
* {{cite book |last=Grabmann |first=Martin |translator=Virgil Michel |title=Thomas Aquinas: His Personality and Thought |publisher=Russell and Russell |date=1963 |url=https://archive.org/details/thomasaquinashis00grab/page/2/mode/2up}}
<!--H-->
* {{Cite book |last=Hampden |first=Renn Dickson |author-link=Renn Dickson Hampden |year=1848 |title=The Life of Thomas Aquinas: A Dissertation of the Scholastic Philosophy of the Middle Ages |url=https://archive.org/details/lifethomasaquin01hampgoog |series=[[Encyclopædia Metropolitana]] |location=London, England |publisher=John J. Griffin & Company}}
* {{Cite book |title=Thomas Aquinas: Theologian of the Christian Life |last=Healy |first=Nicholas M. |publisher=Ashgate |year=2003 |isbn=0-7546-1472-7}}
<!--J-->
* {{cite book |last=Jordan |first=Mark D. |title=Rewritten Theology: Aquinas After His Readers |url=https://books.google.com/books?id=TS3XmU5mTrgC&pg=PA154 |year=2006 |publisher=Wiley |isbn=978-1-4051-1221-5}}
<!--K-->
* {{cite CE1913|first=Daniel Joseph |last=Kennedy|wstitle=St. Thomas Aquinas|volume=14}}
* {{Cite book |title=Summa of the Summa |last=Kreeft |first=Peter |publisher=Ignatius Press |year=1990 |isbn=0-89870-300-X |author-link=Peter Kreeft}}
* {{Cite book |last=Küng |first=Hans |title=Great Christian Thinkers |year=1994 |place=New York |publisher=Continuum Books |isbn=0-8264-0848-6 |author-link=Hans Küng |url-access=registration |url=https://archive.org/details/greatchristianth0000kung}}
<!--M-->
* {{cite book |last=Mulchahey |first=Marian Michèle |title='First the Bow is Bent in Study – ': Dominican Education Before 1350 |url=https://books.google.com/books?id=bK9axCYcbFIC&pg=PA279 |year=1998 |publisher=Pontifical Institute of Mediaeval Studies |isbn=978-0-88844-132-4}}
* {{cite book |last=Murray |first=Paul |title=Aquinas at Prayer: The Bible, Mysticism and Poetry |url=https://books.google.com/books?id=EXYQAAAAQBAJ |date=2013 |publisher=Bloomsbury |isbn=978-1-4411-0589-9 |chapter=10. The collapse, the silence |chapter-url=https://books.google.com/books?id=EXYQAAAAQBAJ&q=%2210.+The+collapse,+the+silence%22&pg=PA27}}
<!--N-->
* {{Cite book |title=Discovering Aquinas |last=Nichols |first=Aidan |publisher=Eerdmans Publishing Company |year=2002 |location=Grand Rapids, Michigan |pages=80–82}}
<!--R-->
* {{cite book |last=Renz |first=Christopher J. |title=In This Light Which Gives Light: A History of the College of St. Albert the Great (1930–1980) |url=https://books.google.com/books?id=t8qt63uOg6IC&pg=PA42 |date=2009 |publisher=Dominican School |isbn=978-1-883734-18-3}}
* {{Cite book |last=Russell |first=Bertrand |title=A History of Western Philosophy |year=1967 |publisher=Simon & Schuster |isbn=0-671-20158-1 |author-link=Bertrand Russell |title-link=A History of Western Philosophy}}
<!--S-->
* {{cite book |last=Smith |first=George H. |author-link=George H. Smith |editor=Ronald Hamowy |title=The Encyclopedia of Libertarianism |url=https://books.google.com/books?id=yxNgXs3TkJYC |year=2008 |publisher=Sage |isbn=978-1-4129-6580-4 |editor-link=Ronald Hamowy |doi=10.4135/9781412965811.n11 |lccn=2008009151 |oclc=750831024 |quote=Individuals, therefore, have a private 'sphere of action which is distinct from the whole.'}}
* {{Cite book |title=Aquinas |last=Stump |first=Eleonore |publisher=Routledge |year=2003 |isbn=0-415-02960-0}}
<!--T-->
* {{Cite book |title=Saint Thomas Aquinas |last=Torrell |first=Jean-Pierre |publisher=[[Catholic University of America Press]] |year=2005 |isbn=978-0-8132-1423-8 |edition=Rev. |location=Washington, D.C. |oclc=456104266}}
<!--V-->
* {{Cite book |title=The Life and Labours of St. Thomas of Aquin |volume=I |last=Vaughan |first=Roger Bede |year=1871 |location=London, England}}
{{refend}}

==External links==
{{Commons category}}
{{Wikiquote}}
{{Wikisource author}}

'''Works of Thomas Aquinas'''
* [http://www.corpusthomisticum.org/ Corpus Thomisticum] – his complete works {{in lang|la}}
* [https://play.google.com/store/apps/details?id=anynet.sqlite.cth.latine ''Corpus Thomisticum''] (A searchable Latin text for Android devices)
* [http://www.documentacatholicaomnia.eu/20_50_1225-1274-_Thomas_Aquinas,_Sanctus.html Documenta Catholica Omnia] – his complete works in PDF files, in {{in lang|la|it|en|de|es|fr|pt}}
* {{Gutenberg author|id=7489}}
* {{Internet Archive author|search=("Thomas Aquinas" OR "Aquinas, Thomas" OR "Thomas of Aquin" OR Aquino OR "Thomas von Aquin")}}
* {{Librivox author|id=1199}}
* [http://www.intratext.com/bti/ Bibliotheca Thomistica IntraText]: texts, concordances and frequency lists
* {{Cite book |title=An Aquinas Reader: Selections from the Writings of Thomas Aquinas |author= Thomas Aquinas |publisher=Fordham University Press |year=2000 |isbn=0-8232-2029-X |editor-last=Mary T. Clark}}
* {{cite web |url=http://documentacatholicaomnia.eu/03d/1225-1274,_Thomas_Aquinas,_Catechismus,_EN.pdf |title=The Catechetical Instructions of Saint Thomas Aquinas |date=9 February 1939 |work=documentacatholicaomnia.eu |location=[[Roman Catholic Archdiocese of Baltimore|Baltimore]] |page=137  |translator-last=Collins |translator-first=Rev. Joseph B. |archive-url=https://web.archive.org/web/20071216073519/http://documentacatholicaomnia.eu/03d/1225-1274,_Thomas_Aquinas,_Catechismus,_EN.pdf |archive-date=16 December 2007 |url-status=live}} (with ''imprimatur'' of the Archbishop [[Michael Joseph Curley|Michael J. Curley]])
* ''[http://www.ccel.org/ccel/aquinas/catena1.titlepage.html Catena Aurea]'' (partial) at ccel.org
* [''Compendium theologiae''] {{Cite book |title=Aquinas's Shorter Summa |author=Thomas Aquinas |publisher=Sophia Institute Press |year=2002 |isbn=1-928832-43-1 |location=Manchester, New Hampshire}}
* ''[http://www.fordham.edu/halsall/basis/aquinas-esse.html On Being and Essence]'' (''{{lang|la|De Ente et Essentia}}'')
* [http://www4.desales.edu/~philtheo/loughlin/ATP/De_Magistro/De_Magistro_11_1.html ''De Magistro''] {{Webarchive|url=https://web.archive.org/web/20120512024320/http://www4.desales.edu/~philtheo/loughlin/ATP/De_Magistro/De_Magistro_11_1.html |date=12 May 2012 }} (''On the teacher'' q. 11, a.1 of ''de Veritate'')
* [''De principiis naturae''] ''[https://web.archive.org/web/20041205070904/http://www4.desales.edu/~philtheo/aquinas/Nature.html The Principles of Nature]''
* [''De rationibus fidei''] [https://web.archive.org/web/20130729150931/http://www.stfrancismagazine.info/ja/images/stories/7_SFM%20August%202010.pdf ''De Rationibus Fidei/Reasons for the Faith against Muslim Objections{{nbsp}}...'']
* [''De unitate intellectus''] {{Cite book |title=Aquinas Against the Averroists: On There Being Only One Intellect |last=McInerny |first=Ralph M. |publisher=Purdue University Press |year=1993 |isbn=1-55753-029-7}}
* ''[https://dhspriory.org/thomas/ContraGentiles.htm Summa contra Gentiles] {{Webarchive|url=https://web.archive.org/web/20190317232316/https://dhspriory.org/thomas/ContraGentiles.htm |date=17 March 2019 }}''
* ''[http://www.newadvent.org/summa Summa Theologica]''
* [http://digitalna.kniznica.info/s/kPxb0qVBwm ''Summa totius logicae'']. [s.n.]: [s.l.], 1880. 96 p. Available online at the [[University Library in Bratislava Digital Library]].
* [https://web.archive.org/web/20070927033837/http://www.domcentral.org/library/thombibl.htm An Aquinas Bibliography]
* [https://aquinas-in-english.neocities.org/ Thomas Aquinas in English]
* [http://hos.ou.edu/galleries//03Medieval/Aquinas/ Online Galleries, History of Science Collections, University of Oklahoma Libraries] {{Webarchive|url=https://web.archive.org/web/20120516184146/http://hos.ou.edu/galleries//03Medieval/Aquinas/ |date=16 May 2012 }}{{snd}}high resolution images of works by Thomas Aquinas in JPEG and TIFF formats
* [https://isidore.co/aquinas/index.html St. Thomas Aquinas's Works in English]

'''Other'''
* {{cite web|url=http://www.virtus-web.ch/sita/foundation.html|title=Thomas Aquinas International Society|archive-url=https://archive.today/20000522125152/http://www.virtus-web.ch/sita/index.htm|archive-date=22 May 2000|url-status=live}}
* {{cite web|url=https://www.comune.aquino.fr.it/home/san-tommaso/la-vita/|title=Biography of Aquinas|date=28 July 2010|language=Italian|location=[[Aquino, Italy]]|archive-url=https://archive.today/20120827034927/https://www.comune.aquino.fr.it/home/san-tommaso/la-vita/|archive-date=27 August 2012|url-status=live|access-date=27 June 2021}}
* {{cite IEP|url-id=aquinas|title=Thomas Aquinas}}
* Brown, Paterson. [https://web.archive.org/web/20101227180503/http://metalog.org/files/tpb/inf.r.html "Infinite Causal Regression"], ''Philosophical Review'', 1966.
* Brown, Paterson. [https://web.archive.org/web/20101227180029/http://metalog.org/files/tpb/nec.b.html "St. Thomas's Doctrine of Necessary Being"], ''Philosophical Review'', 1964.
*{{Citation
| last = Fairweather 
| first = Eugene R.
| author-link = E.R. Fairweather
| title = The Christian Humanism of Thomas Aquinas
| journal = [[Canadian Journal of Theology]]
| volume = XII
| issue = 3
| pages = 194–210
| orig-date = 
| year = 1966
| language = English
| url = https://biblicalstudies.org.uk/pdf/cjt/12-3_194.pdf
| jstor = 
| archive-url = 
| archive-date = 
| doi = 
| id = 
| mr = 
| zbl = 
| jfm = }}
* [https://web.archive.org/web/20060901090647/http://www2.nd.edu/Departments//Maritain/etext/walsh-q.htm "Aquinas the Scholar"] from ''The Thirteenth, the Greatest of Centuries'', ch. XVII by [[James Joseph Walsh]]
* [http://faculty.vassar.edu/brvannor/summa.pdf "Introductory Guide to Reading the ''Summa Theologica'' of Thomas Aquinas"] {{Webarchive|url=https://web.archive.org/web/20171020002520/http://faculty.vassar.edu/brvannor/summa.pdf |date=20 October 2017 }}
* [https://web.archive.org/web/20050105090924/http://www.nd.edu/Departments/Maritain/etext/staamp3.htm On the legend of St. Albert's automaton]
* [http://www.unav.es/cryf/extraterrestriallife.html Aquinas on Intelligent Extra-Terrestrial Life]
* [http://www.poetseers.org/spiritual_and_devotional_poets/christian/st_thomas/ Poetry of St. Thomas Aquinas]
* [https://web.archive.org/web/20051125052858/http://lgxserver.uniba.it/lei/filosofi/autori/tommaso-scheda.htm Biography and ideas] at SWIF/University of Bari/Italy (Italian)
* [http://hdl.loc.gov/loc.rbc/rosenwald.0052 "Postilla in Job"]{{snd}}A photographic facsimile from the [https://www.loc.gov/rr/rarebook/Rare Book and Special Collections Division] at the [[Library of Congress]]
* [http://plato.stanford.edu/entries/aquinas-moral-political/ "Aquinas' Moral, Political and Legal Philosophy"], by [[John Finnis|J. Finnis]] (2011), in the ''[[Stanford Encyclopedia of Philosophy]]''
* [http://www.aquinasonline.com/ Thomistic Philosophy]{{snd}}Inspired by the enduring thought of Saint Thomas Aquinas
* [https://web.archive.org/web/20060206143022/http://www.nd.edu/Departments/Maritain/etext/thomism.htm Article on Thomism] by the Jacques Maritain Center of Notre Dame University
* [http://thomistica.net/ Thomistica.net] news and newsletter devoted to the academic study of Aquinas
* [http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20090917.shtml Discussion of Aquinas], ''[[In Our Time (radio series)|In Our Time]]'', [[BBC Radio 4]], 2009
* [http://www.bartleby.com/210/3/071.html St. Thomas Aquinas] ([http://www.u.arizona.edu/~aversa/aquinas.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20141228125230/http://www.u.arizona.edu/~aversa/aquinas.pdf |date=28 December 2014 }}) biography from [[Alban Butler|Fr. Alban Butler]]'s [http://www.bartleby.com/210/ ''Lives of the Saints'']
* [http://gutenberg.net.au/ebooks01/0100331.txt ''St. Thomas Aquinas''] biography by [[G. K. Chesterton]]
* [http://www.newadvent.org/cathen/14663b.htm "St. Thomas Aquinas"] article by Daniel Kennedy in the ''[[Catholic Encyclopedia]]'' (1912), at NewAdvent.org
* [https://web.archive.org/web/20100609065524/http://www2.nd.edu/Departments/Maritain/etext/thomas.htm ''St. Thomas Aquinas''] biography by [[Jacques Maritain]]
* [http://dspt.edu/site/general/vita-d.-thomae-aquinatis-otto-van-veen-1610 ''Vita D. Thomae Aquinatis''] {{Webarchive|url=https://web.archive.org/web/20181120015105/https://www.dspt.edu/site/general/vita-d.-thomae-aquinatis-otto-van-veen-1610 |date=20 November 2018 }}, a pictorial life of Aquinas from a manuscript by [[Otto van Veen]] (1610)
* [https://www.apronus.com/theology/thomas-aquinas-emulator Thomas Aquinas Emulator Project], research into the use of generative AI to emulate Thomas Aquinas

{{Thomas Aquinas}}
{{Navboxes
|list=
{{Christianity footer}}
{{Dominican Order}}
{{Aristotelianism}}
{{Medieval Philosophy}}
{{Metaphysics}}
{{Epistemology}}
{{Ethics}}
{{Political philosophy}}
{{Social and political philosophy}}
{{History of Catholic theology|collapsed}}
{{Catholic philosophy footer}}
{{Catholic virtue ethics}}
{{Catholic saints}}
{{History of the Catholic Church}}
}}
{{Authority control}}
{{DEFAULTSORT:Thomas Aquinas}}
[[Category:Thomas Aquinas| ]]
[[Category:1225 births]]
[[Category:1274 deaths]]
[[Category:13th-century Christian mystics]]
[[Category:13th-century Christian saints]]
[[Category:13th-century Italian jurists]]
[[Category:13th-century Italian philosophers]]
[[Category:13th-century Italian Roman Catholic priests]]
[[Category:13th-century Italian Roman Catholic theologians]]
[[Category:13th-century Italian writers]]
[[Category:13th-century writers in Latin]]
[[Category:Angelic visionaries]]
[[Category:Anglican saints]]
[[Category:Aristotelian philosophers]]
[[Category:Burials at the Church of the Jacobins]]
[[Category:Characters in the Divine Comedy]]
[[Category:Catholic philosophers]]
[[Category:Christian anti-Gnosticism]]
[[Category:Christian apologists]]
[[Category:Christian critics of Islam]]
[[Category:Christian ethicists]]
[[Category:Critics of atheism]]
[[Category:Doctors of the Church]]
[[Category:Dominican mystics]]
[[Category:Dominican saints]]
[[Category:Dominican theologians]]
[[Category:History of magic]]
[[Category:International law scholars]]
[[Category:Italian Dominicans]]
[[Category:Italian critics of Islam]]
[[Category:Italian nobility]]
[[Category:Italian Roman Catholic writers]]
[[Category:Latin commentators on Aristotle]]
[[Category:Lutheran saints]]
[[Category:Medieval Latin-language poets]]
[[Category:Members of the Dominican Order]]
[[Category:Metaphysicians]]
[[Category:Natural law ethicists]]
[[Category:People from the Province of Frosinone]]
[[Category:Philosophers of law]]
[[Category:Roman Catholic moral theologians]]
[[Category:Salvation in Catholicism]]
[[Category:Scholastic philosophers]]
[[Category:Systematic theologians]]
[[Category:Thomists]]
[[Category:University of Naples Federico II alumni]]
[[Category:University of Paris alumni]]
[[Category:Virtue ethicists]]
[[Category:Writers about religion and science]]
[[Category:Classical theism]]