Thomas studied in Paris and then Cologne under the Dominican polymath Albertus Magnus. He was heavy-set and habitually silent; fellow students mocked him as "the Dumb Ox." Albert's reply became famous: "You call him the Dumb Ox, but one day the bellowing of his teaching will be heard throughout the world."
From the 1250s Thomas taught as a master of theology in Paris and Italy — at Orvieto, at the Dominican house of study in Rome (Santa Sabina), and later back in Paris and Naples. The output was staggering: the Summa Theologiae, the Summa contra Gentiles, commentaries on Aristotle and Scripture, disputed questions, and — at the request of Pope Urban IV around 1264 — the entire liturgy for the new feast of Corpus Christi. He is one of the rare figures whose intellectual and devotional writing are equally first-rate.
Then, on 6 December 1273, while celebrating Mass at Naples, something happened to him. He never described it. Afterward he could not go back to work; when his friend and secretary Reginald of Piperno urged him to finish the Summa, Thomas answered: "I cannot, because all that I have written seems to me like straw compared to what has now been revealed to me." The great work was left unfinished, mid-treatise.
Summoned by Pope Gregory X to the Second Council of Lyon, Thomas set out early in 1274, though already ill. He fell sick on the journey and was taken to the Cistercian abbey of Fossanova, where he died on 7 March 1274, not yet fifty. He was canonized in 1323 by Pope John XXII and declared a Doctor of the Church in 1567.