John Cassian

Saint John Cassian (ca. 360 – 435) (Latin: Joannes Eremita Cassianus, Joannus Cassianus, or Joannes Massiliensis), John the Ascetic, or John Cassian the Roman, was a Christian theologian celebrated in both the Western and Eastern Churches for his mystical writings. He is known both as one of the "Scythian monks" and as one of the "Desert Fathers."