Thomas broke off his former associations and began to lead a life of prayer and penance. Filled with grace, he asked to be admitted to a Franciscan friary as a lay brother. He went on to become a model friar, fasting, keeping vigils, disciplining himself. He wore the cast-off clothes of his brothers. He was frequently wrapped in ecstasy. Though he was never ordained a priest and remained content to serve as a lay brother, Thomas was appointed novice master. Many young men followed in his path of holiness.

   Thomas founded numerous convents of friars in southern Italy. And Pope Martin V called upon him to preach against the Fraticelli, a branch of heretical Franciscans. He was also asked to go to the Orient to promote the reunion of the Eastern and Western Churches. There he was imprisoned and expected to receive the crown of martyrdom. But the pope ransomed him for a large sum of money. Thomas returned to Italy and died on a journey to Rome, where he had hoped to receive permission to return to the Orient.