Cassianus, JOANNES EREMITA, or JOANNES MASSILIENSIS, an early monk and theologian, born most probably about 360. He spent some years among the ascetics of the Egyptian deserts, was ordained by Chrysostom at Constantinople in 403, and afterwards instituted monastic life in Provence, in the south of France. Shortly before 415 he founded at Massilia two monasteries according to the rules laid down in his De Institutis Cænobiorum. One of these monasteries was for nuns; the other was the famous Abbey of St Victor, which under its founder is said to have possessed not less than 5000 inmates, and which served as a model to a multitude of monastic institutions in Gaul and Spain. He died about 448, and was afterwards canonised, his festival falling on 25th July. In his writings Cassianus appears as the opponent of the extreme dogmas of St Augustine respecting grace and free-will. His Collationes Patrum Sæcticorum is a work in 24 chapters, each of which gives a 'spiritual colloquy between monks in the desert of Sketis,' regarding the monastic life and the vexed questions of theology. Cassianus was one of the first of the 'semi-Pelagians' rejecting the extreme view taught by St Augustine of man's worthlessness and natural incapacity for good; his views being substantially identical with what was long afterwards known as Arminianism.
See the edition by Gazeus (1616), and the Life and translation by Gibson (1895).