Son of the Count of Aquino, born in the family castle in Lombardy near Naples. Educated by Benedictine monks at Monte Cassino, and at the University of Naples. He secretly joined the mendicant Dominican friars in 1244. His noble family kidnapped and imprisoned him for a year to keep him out of sight, and deprogram him, but he rejoined his order in 1245.
He studied in Paris from 1245-1248 under Saint Albert the Great, then accompanied Albertus to Cologne. Ordained in 1250, then returned to Paris to teach. Taught theology at University of Paris. He wrote defenses of the mendicant orders, commentaries on Aristotle and Lombard's Sentences, and some bible-related works, usually by dictating to secretaries. He won his doctorate, and taught in several Italian cities. Recalled by king and university to Paris in 1269, then recalled to Naples in 1272 where he was appointed regent of studies while working on the Summa Theologica.
On 6 December 1273 he experienced a divine revelation which so enraptured him that he abandoned the Summa, saying that it and his other writing were so much straw in the wind compared to the reality of the divine glory. He died four months later while en route to the Council of Lyons, overweight and with his health broken by overwork.
His works have been seminal to the thinking of the Church ever since. They systematized her great thoughts and teaching, and combined Greek wisdom and scholarship methods with the truth of Christianity. Pope Leo VIII commanded that his teachings be studied by all theology students. He was proclaimed Doctor of the Church in 1567.
c.1225 at Roccasecca, Aquino, Naples, Italy
7 March 1274 at Fossanuova near Terracina of apparent natural causes; relics interred at Saint-Servin, Toulouse, France; relics translated to the Church of the Jacobins, Toulouse on 22 October 1974