Who Was Thomas Aquinas? His Thought, His Influence, and an Orthodox Response

Few Christian thinkers have shaped a whole tradition as thoroughly as Thomas Aquinas. For Roman Catholics he is a saint, a Doctor of the Church and, in Pope Leo XIII's words, the "chief and master" of the medieval schoolmen.

Orthodox Christians often meet Aquinas second-hand, as the symbol of everything they believe went wrong in the Latin West: rationalism, a legal theology of grace, the Filioque, papal claims. Some of that criticism has a real basis. Some of it is a caricature that would have puzzled the Byzantine theologians of the fourteenth and fifteenth centuries, Palamites among them, who read Aquinas in Greek and admired him. This article tells who he was, what he actually wrote, and how an Orthodox Christian can answer him honestly.

In brief

Thomas Aquinas was born around 1225 near Aquino in southern Italy, became a Dominican friar against his family's wishes, studied under Albert the Great, and taught theology at Paris and in Italy. He died on 7 March 1274 at the abbey of Fossanova while travelling to the Council of Lyons. His unfinished Summa theologiae is a teaching handbook that works through questions, objections and replies, using Aristotle's philosophy as a tool. It contains the "five ways" of arguing that God exists and a systematic account of the Eucharistic change it calls "transubstantiation," a word already in use before him. Late in 1273 he stopped writing after an experience at Mass, reportedly saying that his work seemed like straw. The Orthodox Church shares much of his faith in the Trinity, the Incarnation, the real presence of Christ in the Eucharist and the deification of the human person. It differs from him on the procession of the Holy Spirit, the papacy, purgatory, and the way God is known: following St Gregory Palamas, Orthodoxy holds that the saints share in God's uncreated energies, never in his essence.

Thesis: Aquinas was a holy and brilliant Latin theologian whose faith overlaps with Orthodoxy far more than popular polemic suggests, but whose teaching on the Holy Spirit, the papacy and the vision of God's essence remains a real difference that Orthodox Christians should state carefully and without caricature.

His life

Thomas was the youngest of a large noble family whose castle stood at Roccasecca, between Rome and Naples. The year of his birth is uncertain: the 1912 Catholic Encyclopedia noted that "the end of 1225 is usually assigned," while one early source pointed to 1227.¹ As a boy he studied at the Benedictine abbey of Monte Cassino, where his parents hoped he would one day hold a leading role. As a student at Naples he was drawn instead to the Dominicans, a new order of preaching friars. When he joined them at about nineteen, his parents confined him at Roccasecca for a year before they gave way.²

He studied at Paris and, from 1248, at Cologne under Albert the Great, who was convinced that Christian faith could only gain from serious engagement with philosophy and science. He became a master of theology at Paris in 1256, younger than the statutes allowed, taught there until 1259, spent most of the next decade in Dominican houses at Orvieto and Rome, returned to Paris in 1268, and moved to Naples in 1272.³ In about two decades he wrote, by one estimate, more than eight million words, including commentaries on Scripture and on Aristotle's principal works.⁴

Aquinas says almost nothing about himself in his writings. Many stories about him come from witnesses at his canonization inquiry in 1319, nearly half a century after his death. The philosopher Robert Pasnau calls the basic chronology "fairly well attested" but says the authenticity of many of these stories "is unknowable."⁵

"Like straw"

On 6 December 1273, according to the traditional date, Aquinas had an experience at Mass in Naples that ended his writing. The Summa broke off in the middle of its treatment of penance. In the account preserved by Bartholomew of Capua, who traced it to Thomas's companion Reginald of Piperno, Thomas told Reginald, "I cannot do any more," and then: "Everything I have written seems to me as straw in comparison with what I have seen."⁶ The 1912 Catholic Encyclopedia, working from an earlier edition of the sources, renders the reply differently: "all I have written now appears to be of little value."⁷ {{moderate: The substance of the story, that Aquinas stopped writing after an overwhelming experience of God, comes from people close to him, but it reaches us second-hand and in more than one wording.}}

The story does not mean Aquinas renounced theology: the comparison is with "what I have seen," and he retracted nothing. An Orthodox reader will recognize the pattern from the Fathers: words about God, however true, fall silent before God himself.

Early in 1274 Pope Gregory X summoned him to the Second Council of Lyons, which was to seek reunion with the Greeks, and told him to bring his treatise Against the Errors of the Greeks. He fell ill on the road and died at Fossanova on 7 March 1274.⁸ Pope John XXII canonized him on 18 July 1323. His relics were translated to Toulouse on 28 January 1369, now the date of his memorial in the Roman calendar.⁹ Pius V named him a Doctor of the Church in 1567, and Leo XIII's encyclical Aeterni Patris (1879) said that among the scholastic doctors "the chief and master of all towers Thomas Aquinas."¹⁰

His standing was not always secure. On 7 March 1277, three years to the day after his death, Bishop Stephen Tempier of Paris prohibited the teaching of 219 theses, a number of which seem to touch Aquinas's positions, and later that month at Oxford Archbishop Robert Kilwardby condemned a list that included two of his distinctive doctrines. Two years after the canonization, the bishop of Paris declared that the 1277 condemnation should not be taken to apply to Thomas's teaching.¹¹

The Summa theologiae and its method

The Summa was written for students. Its prologue says that "the doctor of Catholic truth ought not only to teach the proficient, but also to instruct beginners," and complains of "the multiplication of useless questions, articles, and arguments."¹² Each article asks a question, lists the strongest objections, cites an authority "on the contrary," gives Thomas's answer, and replies to each objection.

He used Aristotle, whom he simply calls "the Philosopher," because the recovery of Aristotle's works in Latin had transformed learning in his lifetime. He did not think philosophy could replace revelation. Reason serves faith, he argued, "since therefore grace does not destroy nature but perfects it."¹³ He also set limits on reason that are often forgotten. He held that the world's having a beginning cannot be proved: "By faith alone do we hold, and by no demonstration can it be proved, that the world did not always exist."¹⁴ This puts him at odds with modern defenders of the kalam cosmological argument, which tries to prove exactly that.

The five ways

In the second question of the Summa, Aquinas asks whether God exists. He states the problem of evil as the first objection, and then answers: "The existence of God can be proved in five ways."¹⁵ In outline:

1. Motion. Whatever changes is changed by another, and the series cannot go back without limit, "therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God."
2. Efficient causes. Causes are ordered to one another, so there must be a first cause.
3. Possibility and necessity. Things come into being and pass away, so something must exist necessarily.
4. Degrees of perfection. Things are more or less good and true, which points to what is best and most fully being.
5. Governance. Things without intelligence act for an end, "as the arrow is shot to its mark by the archer."

Two points are often missed. Because Aquinas holds that the world's beginning cannot be proved, his "first mover" is not the first event in a time-line but what holds things in being now. And the five ways are a few paragraphs in a work of thousands of pages; they establish at most a first cause, and the rest of the Summa is needed to say who God is. His reply on evil quotes St Augustine: God would not allow evil "unless His omnipotence and goodness were such as to bring good even out of evil."¹⁶

The Fathers also argued from creation to its Creator: St John of Damascus, whom Aquinas cites often, near the start of his Exact Exposition of the Orthodox Faith argues that whatever is created is changeable and so depends on an uncreated, unchanging Creator.¹⁷ But Orthodoxy has tended to treat such arguments as pointers, not foundations. The knowledge of God that matters is communion with him in prayer, worship and the sacraments.

Transubstantiation

Aquinas did not invent the word "transubstantiation." Joseph Pohle's 1909 Catholic Encyclopedia article says the term "seems to have been first used by Hildebert of Tours (about 1079)." That attribution is uncertain, but the word is found in the Sentences attributed to Master Roland, dated to around 1150.¹⁸ In 1215 the Fourth Lateran Council, which Pohle notes adopted the term, taught that the bread and wine are "changed in substance, by God's power, into his body and blood."¹⁹ Aquinas explained the change systematically. Christ's body does not come to the altar by moving from heaven; rather "the whole substance of the bread is changed into the whole substance of Christ's body." The change is "entirely supernatural, and effected by God's power alone," and "with a name of its own, it can be called 'transubstantiation.'"²⁰ The perceptible qualities of bread and wine, the "accidents," remain, sustained by God without their usual subject.²¹ In 1551 the Council of Trent declared the conversion "suitably and properly called Transubstantiation."²²

Orthodox Christians agree with the heart of this: the bread and wine truly become the Body and Blood of Christ. They hesitate over the philosophical explanation. The Orthodox Synod of Jerusalem in 1672, answering Calvinist influence, used the Greek equivalent of the word (metousiosis), yet added that "by the word 'transubstantiation' the manner is not explained, by which the bread and wine are changed into the Body and Blood of the Lord, — for that is altogether incomprehensible and impossible, except by God Himself."²³ Orthodoxy can accept the word as excluding a merely symbolic view while declining to bind the Church to an Aristotelian account of substance and accidents. The site's article on Catholic and Orthodox views of the Eucharist goes further.

Aquinas and the Greek East

Aquinas knew the Greek Fathers better than most Latin theologians of his day, but he read them in Latin. He quotes St John of Damascus, Dionysius and St John Chrysostom often, and his Catena aurea is a running commentary on the Gospels built from passages of the Fathers.²⁴ The Orthodox scholar Andrew Louth, while praising this interest, notes that "he read all this in Latin, not Greek," and that the Damascene and the Areopagite may read differently in translation.²⁵

His one work aimed at the Orthodox, Against the Errors of the Greeks, was written at the request of Pope Urban IV as a commentary on a Latin dossier of Greek patristic passages compiled by Nicholas, bishop of Cotrone. Its second part argues that the Spirit proceeds from the Son, that "to be subject to the Roman Pontiff is necessary for salvation," and that purgatory exists.²⁶ Even here his tone is not contemptuous. The prologue says the statements of the ancient Greek Fathers "are not to be ridiculed or rejected," and that "Latins and Greeks professing the same faith do so using different words."²⁷ He worked only from the Latin he was given, and in the epilogue he criticizes the compiler's translations.

On the Filioque, the Summa argues that the Spirit must proceed from the Son or the two could not be distinguished, and claims that "the Greeks themselves recognize that the procession of the Holy Ghost has some order to the Son," since they say he is from the Father "through the Son."²⁸ The Orthodox Church confesses the Creed as written in 381, that the Spirit "proceeds from the Father," the one source of both Son and Spirit. Orthodox writers grant that the Spirit is sent through the Son and rests on him, but deny that this makes the Son a cause of the Spirit's eternal existence. See the site's article on the Filioque.

The Byzantine Aquinas

Here the evidence most complicates the usual story. In 1354 Aquinas's Summa contra gentiles was translated into Greek by Demetrios Kydones. Much of the Summa theologiae and other works followed, and Byzantine writers expounded, used and attacked Aquinas until the fall of Constantinople in 1453.²⁹ Marcus Plested's Orthodox Readings of Aquinas (2012) describes a "surprisingly enthusiastic welcome" for him "across the theological spectrum of the late Byzantine world," and notes that many Palamites embraced Thomas, while some Orthodox theologians who resisted union with Rome remained devoted to him.³⁰ Louth, following Plested, notes that the Hesychast controversy "was already settled before the advent of Thomas on the Byzantine scene," and that supporters of Palamas such as Nicholas Cabasilas and Theophanes of Nicaea "made enthusiastic use of elements of Aquinas's theology."³¹ George (Gennadios) Scholarios, appointed Patriarch of Constantinople in 1454 after the city fell to the Ottomans, translated many of Aquinas's works himself.³²

Admiration was not universal, and it did not weaken the Church's commitment to Palamas, whom a council at Constantinople under Patriarch Philotheos proclaimed a saint in 1368. Thomism could also be turned against Palamas: Demetrios Kydones's brother Prochoros used Thomist principles to attack Palamite theology and was condemned under the same Patriarch Philotheos in 1368.³³ {{moderate: Still, the image of a duel between Palamas himself and Aquinas himself is largely a modern construction.}} Palamas's opponent was Barlaam of Calabria, not Aquinas, whose works were not yet available in Greek. Plested argues that modern Orthodox readings have been "resoundingly negative," presenting Aquinas as the archetype of a Western theology "against which the Orthodox East must set its face."³⁴ The earlier controversy is told in the site's article on Gregory Palamas and the Hesychast controversy.

An Orthodox response

Where Orthodoxy agrees

Aquinas confessed the Holy Trinity, Christ as true God and true man as taught at Nicaea and Chalcedon, and the real presence of Christ in the Eucharist. He also taught deification. Quoting Augustine, he writes that "God was made man, that man might be made God," and he calls grace "nothing short of a partaking of the Divine Nature," so that "it is as necessary that God alone should deify" as that only fire can kindle.³⁵ Louth, an Orthodox priest, suggested that Orthodox theologians who actually work through the Summa "will discover much that is congenial."³⁶

Where Orthodoxy differs: knowing and sharing God

The deepest difference concerns how creatures know and share in God. Aquinas teaches that God is "altogether simple," without composition of any kind, and that in heaven "the blessed see the essence of God."³⁷ He knew the Greek objection. His first objection to that article cites St John Chrysostom: "Not prophets only, but neither angels nor archangels have seen God. For how can a creature see what is increatable?" He answers that the Fathers meant that no creature fully comprehends God, and insists that "it is impossible for any created intellect to comprehend God."³⁸ In 1336 Pope Benedict XII defined that the souls of the blessed see the divine essence "with an intuitive vision and even face to face."³⁹

Orthodox theology, following Palamas and the councils of 1341 and 1351, distinguishes God's essence, which no creature will ever see or share, from his uncreated energies, which are God himself acting and giving himself. Vladimir Lossky put it this way: "In deification we are by grace (that is to say, in the divine energies) all that God is by nature, save only identity of nature," and these distinctions "introduce no 'composition' into the divine being."⁴⁰ The saints will see God "face to face" (1 Corinthians 13:12, NKJV) in his glory and light, and will be "partakers of the divine nature" (2 Peter 1:4, NKJV), without ever possessing the divine essence.

A related difference concerns grace. Aquinas calls grace a "quality of the soul," a habit God infuses, which "is said to be created inasmuch as men are created with reference to it."⁴¹ Orthodox writers answer that grace is the uncreated energy of God himself, not a created gift standing between God and the soul. The philosopher David Bradshaw's Aristotle East and West (2004) argues at length that the Latin tradition, from Augustine onward, failed to absorb the Greek understanding of God's energeia, and sees this as one philosophical root of the division of Christendom.⁴² {{debated: Whether Aquinas's "created grace" and Palamas's "uncreated energies" contradict each other or describe the same reality from different angles is still argued by Orthodox and Catholic scholars.}}

Other differences

Beyond the Filioque, Orthodoxy rejects Aquinas's case for the universal jurisdiction of the pope and the Western teaching on purgatory as he presented it, while sharing the ancient practice of praying for the departed. See the site's articles on purgatory and the Council of Florence. Leo XIII later wrote of several councils, Lyons and Florence among them, that "one might almost say that Thomas took part" in their deliberations "against the errors of the Greeks."⁴³ The Orthodox Church does not commemorate Aquinas among its saints.

Objections and replies

A Catholic objection: "The essence-energies distinction divides God." A Thomist can reasonably object that a real distinction between essence and energies breaks God's simplicity, and that Benedict XII rightly taught the vision of God's essence as the fulfilment of 1 Corinthians 13:12. Orthodoxy replies that it posits no part of God hidden behind another part. The energies are God himself acting, and Orthodox theologians insist, with Lossky, that the distinction introduces no composition. The real disagreement is over what simplicity requires and whether a created mind can ever receive God's essence. Here Orthodoxy holds to the apophatic witness of Chrysostom and Dionysius that Aquinas himself quoted.

An Orthodox objection: "Aquinas is a rationalist who turned theology into philosophy." This is the caricature to avoid. Aquinas held that reason serves faith, that the beginning of the world cannot be proved, that no creature comprehends God, and that God alone deifies. Orthodox Christians can criticize his reliance on Aristotelian categories and his conclusions on the Spirit and the papacy without denying his holiness or his love of the truth.

What we can say confidently

• Aquinas was born around 1225 near Aquino and died at Fossanova on 7 March 1274, on his way to the Second Council of Lyons.
• He wrote the Summa theologiae for students and left it unfinished after December 1273.
• The word "transubstantiation" was in use before him, and Lateran IV (1215) had already taught a change of substance; Aquinas gave the doctrine its classic systematic form.
• {{very-strong: Many of his works were translated into Greek from 1354 onward and were read with respect by Byzantine theologians, including Palamites.}}
• He taught that God alone deifies and that grace is a share in the divine nature.
• He taught that the blessed see God's essence, which Orthodoxy, following Palamas, denies.

What remains disputed

• The exact wording, and the meaning, of his late remark about "straw."
• Whether the essence-energies distinction and Thomist divine simplicity are truly incompatible, or partly a matter of vocabulary.
• Whether "created grace" in Aquinas means what Orthodox critics take it to mean.
• How much the 1277 condemnations were aimed at Aquinas himself.
• How far Orthodox theology today can draw on Aquinas, as some Byzantine Palamites did, without blurring real differences.

Conclusion

Thomas Aquinas belongs to the Latin Church, and the Orthodox Church does not count him among its saints. It disagrees with him on matters that touch the Creed itself, above all the procession of the Holy Spirit from the Father, and on the way the saints come to share in God. Honesty requires saying so.

Honesty also requires the rest of the record. Aquinas confessed the faith of Nicaea, taught that God became man so that man might share in God, and laid down his pen before a vision he could not put into words. Some Byzantine theologians read him with gratitude while holding firmly to Palamas. An Orthodox Christian today can do the same: learn from his clarity, answer his errors charitably, and remember with him that every word about God is straw before the living God, who remains beyond all knowing in his essence and yet gives himself wholly in his grace.

Notes

1. Daniel Kennedy, "St. Thomas Aquinas," The Catholic Encyclopedia, vol. 14 (New York: Robert Appleton, 1912), https://www.newadvent.org/cathen/14663b.htm.
2. Robert Pasnau, "Thomas Aquinas," Stanford Encyclopedia of Philosophy (first published 7 December 2022), sec. 1.1, https://plato.stanford.edu/entries/aquinas/.
3. Pasnau, "Thomas Aquinas," sec. 1.1.
4. Pasnau, "Thomas Aquinas," sec. 1.2.
5. Pasnau, "Thomas Aquinas," sec. 1.1.
6. Jean-Pierre Torrell, Saint Thomas Aquinas, vol. 1, The Person and His Work, trans. Robert Royal (Washington, DC: Catholic University of America Press, 1996), 289, as quoted in a secondary source; the printed volume was not opened. Pasnau, sec. 1.1, gives a similar wording.
7. Kennedy, "St. Thomas Aquinas," citing Prümmer's edition of the early lives (the Latin there is modica).
8. Kennedy, "St. Thomas Aquinas"; Pasnau, sec. 1.1.
9. Kennedy, "St. Thomas Aquinas" (canonization and translation of relics); United States Conference of Catholic Bishops, readings for 28 January 2026, "Memorial of Saint Thomas Aquinas, Priest and Doctor of the Church," https://bible.usccb.org/bible/readings/012826.cfm.
10. Kennedy, "St. Thomas Aquinas" (Doctor of the Church, 1567); Leo XIII, Aeterni Patris (4 August 1879), no. 17, https://www.vatican.va/content/leo-xiii/en/encyclicals/documents/hf_l-xiii_enc_04081879_aeterni-patris.html.
11. Pasnau, "Thomas Aquinas," sec. 9; Hans Thijssen, "Condemnation of 1277," Stanford Encyclopedia of Philosophy (rev. 18 December 2023), https://plato.stanford.edu/entries/condemnation/.
12. Thomas Aquinas, Summa theologiae, prologue, trans. Fathers of the English Dominican Province, 2nd rev. ed. (1920), https://www.newadvent.org/summa/. All Summa quotations are from this translation.
13. Summa theologiae I, q. 1, a. 8, ad 2.
14. Summa theologiae I, q. 46, a. 2.
15. Summa theologiae I, q. 2, a. 3.
16. Summa theologiae I, q. 2, a. 3, ad 1, quoting Augustine, Enchiridion 11.
17. John of Damascus, An Exact Exposition of the Orthodox Faith 1.3, trans. E. W. Watson and L. Pullan, NPNF2 vol. 9 (Buffalo, 1899), https://www.newadvent.org/fathers/33041.htm.
18. Joseph Pohle, "The Real Presence of Christ in the Eucharist," The Catholic Encyclopedia, vol. 5 (New York: Robert Appleton, 1909), https://www.newadvent.org/cathen/05573a.htm. On Roland's Sentences (dated 1149-1150 by van den Eynde, about 1155-1156 by Weigand), see Joseph Goering, "The Invention of Transubstantiation," Traditio 46 (1991): 147-170, n. 5 (first page and notes as shown on the publisher's page), https://www.cambridge.org/core/journals/traditio/article/invention-of-transubstantiation/28B3EAB49FD23D310C0DA52E02759D54.
19. Fourth Lateran Council (1215), constitution 1, trans. in N. P. Tanner, ed., Decrees of the Ecumenical Councils, https://www.papalencyclicals.net/councils/ecum12-2.htm.
20. Summa theologiae III, q. 75, a. 4.
21. Summa theologiae III, q. 77, a. 1.
22. Council of Trent, Session 13 (11 October 1551), ch. 4, English translation at papalencyclicals.net (translator not named on the page), https://www.papalencyclicals.net/councils/trent/thirteenth-session.htm.
23. Synod of Jerusalem (1672), Confession of Dositheus, decree 17, adapted from J. Robertson, trans. and ed., The Acts and Decrees of the Synod of Jerusalem (1899), ed. Dennis Bratcher, https://www.crivoice.org/creeddositheus.html. Greek metousiousthai: https://ubipetrusibiecclesia.com/2022/06/21/the-confession-of-patriarch-dositheos-of-jerusalem-1672/.
24. Kennedy, "St. Thomas Aquinas" (on the Catena aurea); Andrew Louth, "The Dumb Ox and the Orthodox," First Things, May 2013, https://firstthings.com/the-dumb-ox-and-the-orthodox/.
25. Louth, "The Dumb Ox and the Orthodox."
26. Thomas Aquinas, Contra errores Graecorum, prologue and part 2, trans. Peter Damian Fehlner, rev. Joseph Kenny, https://isidore.co/aquinas/english/ContraErrGraecorum.htm; Kennedy, "St. Thomas Aquinas" (written by order of Urban IV).
27. Contra errores Graecorum, prologue and epilogue, trans. Fehlner and Kenny.
28. Summa theologiae I, q. 36, a. 2.
29. Louth, "The Dumb Ox and the Orthodox"; Lowell Clucas, "The Triumph of Mysticism in Byzantium in the Fourteenth Century," in Speros Vryonis Jr., ed., Byzantine Studies in Honor of Milton V. Anastos, Byzantina kai Metabyzantina 4 (Malibu, 1985), ch. 5, https://mail.myriobiblos.gr/texts/english/clucas_mysticism5.html (Demetrios Kydones as "the translator of Thomas Aquinas").
30. Marcus Plested, Orthodox Readings of Aquinas (Oxford: Oxford University Press, 2012), publisher's description, https://epublications.marquette.edu/marq_fac-book/223.
31. Louth, "The Dumb Ox and the Orthodox."
32. Katerina Ierodiakonou and Börje Bydén, "Byzantine Philosophy," Stanford Encyclopedia of Philosophy (rev. 16 September 2018), https://plato.stanford.edu/entries/byzantine-philosophy/; Plested, publisher's description.
33. Clucas, "The Triumph of Mysticism," ch. 5 (Prochoros Kydones); Orthodox Church in America, "Saint Gregory Palamas, Archbishop of Thessalonica," https://www.oca.org/saints/lives/2026/11/14/103303-saint-gregory-palamas-archbishop-of-thessalonica.
34. Plested, publisher's description.
35. Summa theologiae III, q. 1, a. 2 (quoting Augustine); I-II, q. 112, a. 1.
36. Louth, "The Dumb Ox and the Orthodox."
37. Summa theologiae I, q. 3, a. 7; I, q. 12, a. 1.
38. Summa theologiae I, q. 12, a. 1, obj. 1 and ad 1; I, q. 12, a. 7.
39. Benedict XII, Benedictus Deus (1336), https://www.papalencyclicals.net/ben12/b12bdeus.htm.
40. Vladimir Lossky, The Mystical Theology of the Eastern Church (Cambridge: James Clarke, 2005 printing), excerpt "Essences and Energies" at https://myriobiblos.gr/texts/english/lossky_essences.html.
41. Summa theologiae I-II, q. 110, a. 2 and ad 3.
42. David Bradshaw, Aristotle East and West: Metaphysics and the Division of Christendom (Cambridge: Cambridge University Press, 2004), as summarized in an unsigned review posted on religiocity.org (18 November 2007) and described there as written for WTJ, https://www.religiocity.org/2007/11/18/bradshaw-_aristotle-east-west_-review-for-_wtj_/.
43. Leo XIII, Aeterni Patris, no. 22.

Bibliography

Primary sources

• Thomas Aquinas. Summa theologiae. Trans. Fathers of the English Dominican Province. 2nd rev. ed., 1920. New Advent.
• Thomas Aquinas. Contra errores Graecorum. Trans. Peter Damian Fehlner, rev. Joseph Kenny. isidore.co.
• Fourth Lateran Council (1215), constitution 1. In N. P. Tanner, ed., Decrees of the Ecumenical Councils.
• Council of Trent, Session 13 (1551). English translation, papalencyclicals.net.
• Benedict XII. Benedictus Deus. 1336.
• Leo XIII. Aeterni Patris. 1879.
• The Holy Bible, New King James Version.

Orthodox and patristic sources

• Synod of Jerusalem (1672). Confession of Dositheus. Trans. J. Robertson, 1899. Ed. Dennis Bratcher, crivoice.org.
• John of Damascus. An Exact Exposition of the Orthodox Faith. Trans. E. W. Watson and L. Pullan. NPNF2 vol. 9. Buffalo, 1899.
• Orthodox Church in America. "Saint Gregory Palamas, Archbishop of Thessalonica." oca.org.
• Lossky, Vladimir. The Mystical Theology of the Eastern Church. Cambridge: James Clarke.
• Louth, Andrew. "The Dumb Ox and the Orthodox." First Things, May 2013.
• Plested, Marcus. Orthodox Readings of Aquinas. Oxford: Oxford University Press, 2012.
• Bradshaw, David. Aristotle East and West: Metaphysics and the Division of Christendom. Cambridge: Cambridge University Press, 2004.

Other scholarship

• Pasnau, Robert. "Thomas Aquinas." Stanford Encyclopedia of Philosophy, 2022.
• Thijssen, Hans. "Condemnation of 1277." Stanford Encyclopedia of Philosophy, rev. 2023.
• Clucas, Lowell. "The Triumph of Mysticism in Byzantium in the Fourteenth Century." In Speros Vryonis Jr., ed., Byzantine Studies in Honor of Milton V. Anastos. Byzantina kai Metabyzantina 4. Malibu, 1985.
• Goering, Joseph. "The Invention of Transubstantiation." Traditio 46 (1991): 147-170.
• Ierodiakonou, Katerina, and Börje Bydén. "Byzantine Philosophy." Stanford Encyclopedia of Philosophy, rev. 2018.
• Torrell, Jean-Pierre. Saint Thomas Aquinas. Vol. 1, The Person and His Work. Trans. Robert Royal. Washington, DC: Catholic University of America Press, 1996.

Sources from the tradition being discussed (Roman Catholic)

• Kennedy, Daniel. "St. Thomas Aquinas." The Catholic Encyclopedia, vol. 14. New York: Robert Appleton, 1912.
• Pohle, Joseph. "The Real Presence of Christ in the Eucharist." The Catholic Encyclopedia, vol. 5. New York: Robert Appleton, 1909.
• United States Conference of Catholic Bishops. Readings for the Memorial of Saint Thomas Aquinas, 28 January 2026.