Thomas Aquinas, St

Thomas Aquinas, St (c.1225–74), philosopher and theologian. At the age of 5 he was given to the abbey of Monte Casino, in the expectation that he would become abbot. When the troops of Frederick II occupied the abbey in 1239, Thomas went to Naples, where he joined the Dominican Order. He was sent to Paris. Here he came under the influence of St Albertus Magnus, with whom he went to Cologne (1248–51). Returning to Paris, he lectured on various texts, wrote against Avicebron, and began the Summa contra Gentiles, which was apparently designed for the use of Dominican missionaries in their dealings with non-Christians. In Italy (1259–68) he taught in various Dominican houses, composed a liturgy for the Feast of Corpus Christi, and began the Summa Theologiae, which was originally designed as a handbook for friars not bound for university study. Back in Paris, he held one of the Dominican chairs in the University from 1268 to 1272. He was involved in controversy with the secular masters over the rights of the mendicants and also with Siger of Brabant, as well as with conservative theologians opposed altogether to the use of Aristotle in theology. In 1272 he went to Naples to set up a Dominican studium. A mysterious traumatic experience in 1273 ended his teaching and writing.

He left a huge body of writings, including biblical commentaries, commentaries on works of Aristotle, academic disputations, and works of spirituality, as well as his Summae. Although he accorded primacy to revelation, he recognized an autonomy proper to human reason and clearly delineated the spheres of faith and reason. He held that knowledge necessarily begins with sense perception. This conviction that valid arguments start with facts of the natural world gave his proofs for the existence of God their characteristic form (for these see QUINQUE VIAE). Also running through his thought are the antitheses between potency and act (God being ‘pure act’), between matter and form, and between essence and existence.

Thomas declared theology, distinct from philosophy, to be a science, in as much as it is an ordered body of knowledge, even though it depends for its first principles on a higher knowledge that it cannot itself test or prove, namely the knowledge which God reveals. The fundamental truths revealed by God are the Trinity of Persons in the Godhead and the Incarnation of the Word as a Person of human nature. But he held that revelation was also necessary for truths which reason can attain unaided, such as the existence of God, since without revelation such ‘truths would be known only to a few … and with an admixture of error’. He treated theology as a single discipline which embraces the whole life of the Church, including worship, morals, and spiritual practice. Seeing God as the only subsistent being, the necessary being who cannot not exist, Thomas was able to resolve the dichotomy between immanence and transcendence, positing God's intimate presence at the centre of every creature as the cause of its being. He emphasized the role of Christ's humanity in the Incarnation and its causal relation to the work of redemption. This work is continued through the sacraments, which are an extension of His humanity. Thomas held the Eucharist was the highest of the sacraments, and that as the ultimate purpose of Orders was the Eucharist, the priesthood was the highest order and the episcopate therefore not a separate order. He utilized the Aristotelian philosophy of substance and accidents to develop a systematic understanding of transubstantiation.

Various of his teachings were attached before and after his death; a formal condemnation by the Abp. of Paris in 1277 was averted only by the intervention of the Roman Curia. By the time of the Council of Trent the RC Church had accepted the substance of his teaching as an authentic expression of doctrine. Feast day, 28 Jan. (formerly 7 Mar.).