Saint of the Catholic Church, born in Old Castile; distinguished for his zeal in the conversion of the heretic; essayed the task by simple preaching of the Word; sanctioned persecution when persuasion was of no avail; countenanced the crusade of Simon de Montfort against the Albigenses for their obstinate unbelief, and thus established a precedent which was all too relentlessly followed by the agents of the Spanish Inquisition, the chiefs of which were of the Dominican order, so that he is ignominiously remembered as the "burner and slayer of heretics" (1170-1221). Festival, Aug. 4.