Saint Thomas Aquinas (1225–74)

Encyclopædia Orbis Latini

Italian philosopher and theologian, Doctor of the Church, known as the Angelic Doctor, b. Rocca Secca (near Naples). He is the greatest figure of scholasticism, one of the principal saints of the Roman Catholic Church, and founder of the system declared by Pope Leo XIII (in the encyclical Aeterni Patris, 1879) to be the official Catholic philosophy.


St. Thomas came of the ruling family of Aquino, was educated as a child at Monte Cassino, and later studied at Naples. To his family’s disappointment he entered (1244) the new Dominican order. In 1245 he began to study in Paris with Albertus Magnus, whose favorite pupil he became, and in 1248 he accompanied Albertus to Cologne. From there, Thomas went again (1252) to Paris, where he gained a great reputation and became professor of theology. He was leader of the friars in the controversy that occurred when the seculars sought to limit the friars’ privileges at the university. After 1259 he spent several years in Italy as professor and adviser at the papal court.

His return to Paris (1269) was probably precipitated by the furor over Siger de Brabant and his Averroistic reading of Aristotle. The doctrinal struggle with Siger resulted in victory for Thomas and the triumph of his position. In 1272 he left Paris for Naples to organize a house of studies. Two years later when he and his companion, Brother Reginald, were at Fossanuova, on the way to the Council of Lyons, where he was to be a papal consultant, St. Thomas died.

He was canonized in 1323 and was proclaimed a Doctor of the Church in 1567. His tomb is in the Basilica of St. Sernin at Toulouse. Feast: Mar. 7. In art St. Thomas is usually associated with a sacramental cup (representing his devotion to the sacrament) or a dove (representing the inspiration of the Holy Spirit) or depicted with a sun on his breast.

Philosophy and Work

St. Thomas’s student nickname was the Dumb Ox, because he was slow in manner and quite stout. He was, however, a brilliant lecturer and a clear, sharp thinker, as his works show—not only in their rigid application of reason, but also in their Latin diction, which is admirably exact and simple. His spiritual character is manifest in the humility and charity of his conduct and the use to which he put his theories in his devotional works, notably in the Mass and office for the feast of Corpus Christi (June 21), which he wrote at Urban IV’s request (1264). The four hymns of this Mass and office, Laude Sion Salvatorem, Pange Lingua, Sacris solemniis, and Verbum supernum (ending with O Salutaris Hostia), are classed among the greatest of Christian hymns.

No single work of St. Thomas can be said fully to reveal his philosophy. His works may be classified according to their form and purpose. The principal ones are Commentary in the Sentences (a series of public lectures; 1254–56), his earliest great work; seven quaestiones disputatae (public debates; 1256–72); philosophical commentaries on Aristotle’s Physics, Metaphysics, De anima, Ethics, part of the De interpretatione, and the Posterior Analytics; treatises on many subjects, including the Summa contra Gentiles (1258–60); and, most important of all, Summa theologica (1267–73), an incomplete but systematic exposition of theology on philosophical principles. St. Thomas’s philosophy is avowedly Aristotelian; the methods and distinctions of Aristotle are adapted to revelation.

The 13th cent. was a critical period in Christian thought, which was torn between the claims of the Averroists and Augustinians. Thomas opposed both schools, the Averroists led by Siger de Brabant, who would separate faith and truth absolutely, and the Augustinians, who would make truth a matter of faith. St. Thomas held that reason and faith constitute two harmonious realms in which the truths of faith complement those of reason; both are gifts of God, but reason has an autonomy of its own. Thus he vindicated Aristotle against those who saw him as the inspiration of Averroës and heresy.

The first principle of philosophy according to St. Thomas is the affirmation of being. From this he proceeded to a consideration of the manner in which the intellect achieves knowledge. For humans all knowledge begins by way of the senses, which are the medium through which he grasps the intelligible world, the universal. According to the position of Thomas, which is known as moderate realism, the form or the universal may be said to exist in three ways: in God, in things, and in the mind (universals). He argues that it is by the knowledge of things that we come to know of God’s existence. In the natural order what God is can be known only by analogy and negation.

Thomas’s conviction that the existence of God can be discovered by reason is shown by his proofs of the existence of God. His metaphysics relies on the Aristotelian concepts of potency and act, matter and form, being and essence. A thing that requires completion by another is said to be in potency to that other; the realization of potency is called actuality. The universe is conceived of as a series of things arranged in an ascending order of potency, an act at once crowned and created by God, who alone is pure act. Two other pairs of metaphysical concepts—matter and form, essence and being—are special cases of potency and act. St. Thomas’s moral philosophy is derived from these distinctions as well, since the opposite of being does not exist and since the good is identical with being, evil is but the absence of good.


For a long time Thomas was either ignored or misunderstood by even the greatest philosophers, but his teachings ultimately triumped. That they are official in the Roman Catholic Church does not mean that Catholics may not adhere to other philosophies, notably the Scotist teachings, developed from the doctrines of Duns Scotus. St. Thomas’s synthesis is now recognized as one of the greatest works of human thought. His wide-embracing philosophy can be applied to every realm of human life.

The terms New Thomism, neo-Thomism, and neo-scholasticism are used for a school of philosophy of the 20th cent. The Catholic leaders of this school were Étienne Gilson and Jacques Maritain, who sought to apply Thomistic principles to modern economic, political, and social conditions. Non-Catholics also have adapted Thomistic principles to modern life; a leader among them is Mortimer Adler.


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