Dominic continued to preach and to debate where he could, and in 1215 he founded an order of preachers, who were to live in poverty, and devote themselves to studying philosophy and theology and to combatting false doctrine by logical argument rather than by the use of force. He was convinced that a major obstacle to the conversion of heretics was the material wealth of some of the clergy, which made plausible the accusation that they were concerned for their purses and not for the glory of God, and made workers indisposed to hear them. He therefore determined that the brothers of his order should live lives of poverty and simplicity, being no better off materially than those they sought to convert. When he was in Rome, seeking authorization for his order from the Pope, the Pope gave him a tour of the treasures of the Vatican, and remarked complacently (referring to Acts 3:6), "Peter can no longer say, 'Silver and gold have I none.'" Dominic turned and looked straight at the Pope, and said, "No, and neither can he say, 'Rise and walk.'" He got the permission he was seeking, and the order grew and flourished. Officially known as the Order of Preachers (hence the letters O.P. after the name of a member), it was informally known as the Dominicans, or the Blackfriars (from the colour of their cloaks). Two of their best-known members are Albertus Magnus (Albert the Great, 1200-1280), who was famous for his learning in numerous fields, and his pupil Thomas Aquinas (1225-1274), who wrote reconciling Christian theology with the philosophy of Aristotle, which was then being rediscovered in western Europe, and was thought by many to be a threat to Christianity. In later years, the Order forgot its commitment to "logic and persuasion, not force" as the means of bringing men to Christian truth, and many of its members were active in the Inquisition.
Dominic was three times offered a bishopric, and refused, believing that he was called to another work. He died in 1220 in Bologna, Italy, after a preaching mission to Hungary. His emblem in art is a dog with a torch in its mouth, a pun on his name (the Dominicans are sometimes called the "Domini canes", the hounds of the Lord), and a reference to his relying on the power of preaching.