When Thomas was 19 he decided that he would join the Dominicans. His family was upset, because they expected him to join the Benedictines like his uncle. It's hard for me, as a non-Catholic nearly 800 years later, to understand this division, but his family was so upset by this that they imprisoned him in one of the family castles. While imprisoned his brothers tried to have a prostitute seduce him, but according to legend he fended her off with a hot poker. His reward was an angelic visit which served to strengthen his belief in celibacy.
After about a year, his mother helped him escape from the castle. She apparently felt that it would be better for the family if he escaped before political force was wielded to free him. Thomas went to Paris and gained some fame there. He was quiet and some of his fellow students thought he was stupid. This prompted his teacher, Albert Magnus, to say, "You call him the dumb ox, but in his teaching he will one day produce such a bellowing that it will be heard throughout the world".
Thomas bounced around from position to position, both teaching and learning. Around 1265, when he was 40, he was asked to be a papal theologian and do some teaching near Rome. It was then that he developed 'Summa Theologica', which he wrote as an instruction for beginning students. It is one of the foremost works of philosophy and ethics in the entire Catholic canon.
In December of 1273, this happened:
On 6 December 1273 at the Dominican convent of Naples in the Chapel of Saint Nicholas after Matins Thomas lingered and was seen by the sacristan Domenic of Caserta to be levitating in prayer with tears before an icon of the crucified Christ. Christ said to Thomas, "You have written well of me, Thomas. What reward would you have for your labor?" Thomas responded, "Nothing but you, Lord." After this exchange something happened, but Thomas never spoke of it or wrote it down. Because of what he saw, he abandoned his routine and refused to dictate to his socius Reginald of Piperno. When Reginald begged him to get back to work, Thomas replied: “Reginald, I cannot, because all that I have written seems like straw to me” (mihi videtur ut palea). What exactly triggered Thomas's change in behavior is believed by Catholics to have been some kind of supernatural experience of God.A few months later he died after an accident with a tree branch. There were some later rumors that he had been poisoned but his contemporaries didn't mention any such thing. As he was given last rites he said "I receive Thee, ransom of my soul. For love of Thee have I studied and kept vigil, toiled, preached and taught....". He was canonized 50 years later. Thomas Aquinas is the patron saint of all Catholic schools.