Texts

Links to On-line Texts of St. Thomas Aquinas.

(Incomplete – To suggest additions, please comment below)

Opera Omina – The Complete Works of St. Thomas Aquinas in Latin

• Corpus Thomisticum, collected and maintained by Enrique Alarcón at the Universidad de Navarra, Spain.  The texts are grouped in blocks of several chapters or questions.  The site also has other useful information including a bibliography. 
• The Aquinas Institute is publishing the complete works of St. Thomas Aquinas in Latin and English in three formats: online, eBook, and print. The collection is not yet complete, but many newly translated texts are available.
  • — The online edition is searchable and contains critical notes on manuscript variations.

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Individual Texts of Aquinas: English Title – Latin Title (Date of composition.)

• On the Principles of Nature – De Principiis Naturae (1252-56)
  • English. (HTML text of translation by Gyula Klima (from course material of A. Freddoso)).
  • English. (Page proofs of translation by Gyula Klima with his notes and Introduction).
  • English. (Translation by Joseph Kenny, OP).
  • English. (Translation by Professor Gerard Campbell via Internet Archive).
• On Being and Essence – De Ente et Essentia (1252-56)
  • Latin and English. (via Logic Museum).
  • English. (Translation by Robert T. Miller via Fordham University Internet Medieval Sourcebook.)
  • English. (Page proofs of translation by Gyula Klima with his notes).
  • Latin. (E-text with word lists, concordances, and statistics via IntraText).
  • Rусском языке (Russian) [No longer active – links to Internet Archive Wayback Machine]. (via Философская библиотека Средневековья, Русской Христианской Христианской Академией в Санкт-Петерберге (via Philosophical Library of the Middle Ages of the Russian Christian Academy in St. Petersburg))
• Commentary on the Sentences of Peter Lombard – Scriptum super libros Sententiarum (1252-1256) (All texts (Latin and English) via Aquinas Translation Project)
  Book I
  • Distinction 2. Question 1: Concerning the Unity of the Divine Essence
    Article 1. Whether there is only one God
  • Distinction 3. Question 1: Concerning Man’s Knowledge of God
    Article 1. Whether God can be known by a created intellect
    Article 2. Whether God’s existence is self-evident
    Article 3. Whether God can be known by man through creatures
    Article 4. Whether philosophers knew the Trinity from creatures by a natural knowledge
  • Distinction 8. Question 4: Concerning God’s Simplicity
    Article 1. Whether God is entirely simple
  • Distinction 10: The Holy Spirit as Love
    Proemium
    Article 1. Whether the Holy Spirit proceeds as love
    Article 2. Whether the Holy Spirit is the love which the Father has into the Son
    Article 3. Whether the Holy Spirit is the union of the Father and the Son
    Article 4. Whether the Person proceeding through the mode of love is properly called the Holy Spirit
    Article 5. Whether there are only three Persons in God
    A Little Note
  • Distinction 37. Question 1: Concerning God’s Existence in Things
    Article 1. Whether God is in things
    Article 2. Whether God is in all things by power, presence, and essence; in the saints by grace; in Christ by being
  • Distinction 37. Question 2: Concerning God’s Omnipresence
    Article 1. Whether God is everywhere
    Article 2. Whether to be everywhere belongs to God alone
    Article 3. Whether to be everywhere belongs to God from eternity
• Book II
  • Distinction 43. Question 1: Concerning the Sin against the Holy Spirit
    Proemium/Introduction
    Article 1. Whether there is a sin against the Holy Spirit
    Article 2. Whether the sin against the Holy Spirit is a particular kind of sin
    Article 3. Whether the species of the sin against the Holy Spirit are fittingly designated in (the Lombard’s) text
    Article 4. Whether the sin against the Holy Spirit is unforgivable
    Article 5. Whether someone can sin against the Holy Spirit in the first act of sin
    Article 6. Whether Adam Sinned Against the Holy Spirit
• Book IV
  • Distinction 8. Question 1: Concerning the Eucharist
    Article 1. The sacramentality, unicity, and names of the Eucharist
    Article 2. On the prefiguration of this sacrament
    Article 3. The necessity of instituting this sacrament, and at what time
    Article 4. On the Eucharistic fast
  • Distinction 15. Question 3: Concerning Fasting
    Article 1. Whether Isidore appropriately defines fasting
    Article 2. Whether all are obliged without dispensation to keep the fast instituted by the Church
    Article 3. Whether times such as these ought to be determined for fasting, as (those) instituted by the Church
    Article 4. Whether the fast is broken by two meals

• Commentary on Boethius’s On the Trinity – Super Boetium De Trinitate (1258-59)
  • Latin – English. (via Logic Museum).
• On the Truth of the Catholic Faith – Summa contra Gentiles (1259-64).
  • English. (Translation by Joseph Rickaby, SJ. via Jacques Maritain Center via the Wayback Machine of the Internet Archive (formerly at the University of Notre Dame).
  • English. (Translation by Joseph Rickaby, SJ. via Christian Classics Ethereal Library).
• On the Power of God – Quaestio Disputata de Potentia (1265-66)
  • Latin – English. (via Logic Museum).
• Summa of Theology – Summa Theologiae (1265-74)
  • English. (via New Advent).
  • English. (via Christian Classics Ethereal Library).
  • English. (Translated by A. Freddoso. Each Question is available in .pdf format through Part III, Q. 67, as of December 23, 2025).
  • English. (via Sacred Texts)
  • English. (E-text with word lists, concordances, and statistics via IntraText).
  • Latin and English. (via The Logic Museum).
• Commentary on Aristotle’s Physics – In VIII libros Physicorum (1269-70)
  • Latin – English. (via Logic Museum).
• Commentary on the Metaphysics of Aristotle – In duodecim libros Metaphysicorum expositio (1269-72)
  • Latin – English. (via Logic Museum).
• Commentary on Aristotle’s Posterior Analytics – In Libros Posteriorum (1269-72)
  • Latin – English. (via Logic Museum).
• On the Eternity of the World – De Aeternitate Mundi (1270).
  • Latin and English. (via The Logic Museum).
  • English. (Translation by Robert T. Miller via Fordham University Internet Medieval Sourcebook.)
• Commentary on Aristotle’s On Interpretation – In Perihermeniam (1270-71)
  • Latin – English. (via Logic Museum).
• On the Mixture of the Elements – De mixtione elementorum ad Magistrum Philippum de Castrocaeli (1270-1271)
  • English. (Page proofs of translation by Gyula Klima).
• On the Motion of the Heart – De Motu Cordis (1270-71)
  • Latin and English. (via Aquinas Translation Project)
• Commentary on the Psalms – Postilla super Psalmos (1272-73)
  • Latin and English, (via Aquinas Translation Project).
• Disputed Question on the Union of the Word Incarnate – Quaestio Disputata de Unione Verbi Incarnati (1272, but see note on the dating of De Unione.)(All texts (Latin and English) via Aquinas Translation Project)
  • Article 1: Whether this union was brought about in the person or in the nature?
  • Article 2: Whether there is only one hypostasis or suppositum in Christ or two?
  • Article 3: Whether Christ is one or two in the neuter?
  • Article 4: Whether there is only one being in Christ?
  • Other texts dealing with the same subject matter:
    • III Sent., d. 5, q. 1, a. 2
    • III Sent., d. 5, q. 1, a. 3
    • III Sent., d. 6, q. 2, a. 1
    • III Sent., d. 6, q. 2, a. 2
    • Quodlibet IX, q. 2, a. 1 [2]
    • Quodlibet IX, q. 2, a. 2 [3]

• Opuscula varia (All texts (Latin and English) via Aquinas Translation Project)
  • On the Teacher: Can Humans teach each other? – De Magistro (q. 11, a.1 of De Veritate (1256–1259)
  • Dedication of the Catena on Saint Mark’s Gospel (1263ff)
  • Dedication of the Catena on Saint Matthew’s Gospel (1263ff)
  • On the Hidden Workings of Nature – De operationibus occultis naturae (1269–1272)

Other sites with links to Thomistic texts (from which most of the above links are drawn).

• Thomas Aquinas in English – A complete bibliography compiled and maintained by Thérèse Bonin.
• Elliot Polsky‘s ThomisticMetaphysics.com has pages devoted to
  • Books by Aquinas – Best Online and Print Editions for Citing and Reading
  • Books about Aquinas – a list of biographies of Saint Thomas Aquinas and general introductions to his thought, as well as books and articles on Thomistic topics arranged thematically.
• The Aquinas Translation Project – Dr. Stephen Loughlin, Director (now President of Saint Bernard’s School of Theology and Ministry).
• Robert Pasnau’s Provisionalia: Index of Scholastic Texts (including Aquinas).

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Updated August 11, 2025