The Church celebrates the feast of St. John Cassian on July 23, an eastern monk and theological writer. He went to Palestine in 380 with a companion, Germanus, and became a monk in Egypt. In 400 he entered into the discipleship of St. John Chrysostom, going to Rome to defend the much-oppressed saint before Pope Innocent I.
Ordained in Rome, John founded several monasteries in southern France, near Marseilles, thus helping to pioneer monasticism in Europe. His two main writings, Institutes of the Monastic Life and Conferences on the Egyptian Monks, were much praised by St. Benedict and were extremelly influential for a very long time; the former had a direct impact upon Benedict during the time that he was composing his famed Rule.
John also authored the work De Incarnatione Doniini, in seven books, at the behest of Pope Leo I the Great so as to inform the Western Church of the details of the teachings of the heresiarch Nestorius.