theologian and liturgist. Probably a native of Cremona, he studied at Paris and later taught theology there. In 1194 he was invited to take charge of the cathedral school at Mainz. From 1206 to 1209 he was head of the Parisian schools as chancellor of the cathedral. His main theological work, his Summa Theologica, follows the pattern of Peter Lombard's Sentences. His Tractatus de Officiis, on the liturgical year, was the main source of the standard work of William Durandus. He was one of the ablest of the Parisian theologians of the late 12th century.