Johannes Cassianus, a founder of monastic institutions, believed to have been born about 350, and to have died in Marseilles about 433. According to other accounts, he was a native of Greece, born about 300, and died about 448. He went when young to the Holy Land, remained some time in Bethlehem, spent many years among the ascetics of Egypt, was ordained about 403 as deacon by Chrysostom at Constantinople, and sent on a mission to Rome relative to the controversy with the Arians. Soon afterward he founded at Marseilles a nunnery and the abbey of Saint Vic-tor, which is said to have contained during his time 5,000 inmates. His De Institutis Cozno-biorum and OollationesPatrum Sceticorum constitute a code of monastical institutions, which, though strenuously opposed by St. Augustine, acquired great popularity, and was subsequently much admired by Thomas Aquinas, by the recluses of Port Royal, who adopted his regulations as the model of their monastic life, and by Arnaud d'Andilly, who embodied the ideas of Cassianus in his Vie des peres du desert.

He was eventually canonized, and his anniversary, July 23, was long celebrated at Marseilles. The best edition of his collected works is that reprinted at Leipsic in 1733.