The Dominican Order was established by St. Dominic in 1214 when he gathered a group of priests in the castle at Casseneuil in Languedoc owned by Count Simon IV of Montfort, who headed a crusade against the Albigensians whose religious inclinations the papacy deemed heretical. In 1216, the saint traveled to Rome to obtain papal approval for the order, which was duly granted. Unlike the self-sufficient medieval monastic orders, the Dominicans were a mendicant group that relied on charity. Their main purpose was to convert the Albigensians and to preach the word of God in the vernacular language. In 1229, the papacy established the Inquisition and the Dominicans were assigned to carry it out. This is what earned them the name Domini canes, the Lord's dogs who fight heresy. They are depicted in Andrea da Firenze's Guidalotti Chapel at Santa Maria Novella (1348-1355) in the Dominican church of Florence as ferocious dogs who chase the wolves of heresy. Among the most important Dominicans is St. Thomas Aquinas, one of the greatest theologians in history.
Historical dictionary of Renaissance art. Lilian H. Zirpolo. 2008.