Cassian the Deacon

Cassian, a Scythian by birth, was ordained deacon at Constantinople by Bishop John the Great, and presbyter at Marseilles. He founded two monasteries, one for men and one for women, which are still standing. He wrote from experience and in forceful language, or, to put it more plainly, with meaning behind his words and action behind his talk. He covered the whole field of practical direction for monks of every kind in the following works. On Dress; also On the Canon of Prayers, and the Practice of Saying the Psalms (for in the Egyptian monasteries these are said day and night), three books. One book of Institutes. Eight books On the Origin, Nature and Remedies of the Eight Principal Sins, a book on each sin. [a]

He also compiled Conferences with the Egyptian Fathers, as follows: On the Aim of a Monk and His Creed; On Discretion; On Three Callings to the Service of God; On the Warfare of the Flesh against the Spirit and of the Spirit against the Flesh; On the Nature of All Sins; On the Slaughter of the Saints; On Fickleness of Mind; On Principalities; On the Nature of Prayer; On the Duration of Prayer; On Perfection; On Chastity; On the Protection of God; On the Knowledge of Spiritual Things; On the Divine Graces; On Friendship; On Whether to Define or Not to Define; On Three Ancient Kinds of Monks and a Fourth Recently Arisen; On the Aim of Cenobites and Hermits; On True Satisfaction in Repentance; On the Relaxing of the Fast in the Fifty Days; On Illusions in the Night; On the Saying of the Apostle, “For the good that I want to do, I do not do, but the evil that I do not want, that I do”; and On Mortification. Finally, at the request of Leo the archdeacon, afterward bishop of Rome, he wrote seven books against Nestorius, On the Incarnation of the Lord. With this work he made an end both of writing and of living, at Marseilles, in the reign of Theodosius and Valentinian.