One of the principal ideas in oriental anthropology is that of the divinization of man. The author studies this idea in John Cassian and draws the conclusion that not only was it known to Cassian, but indeed it is the filter through which he views the question of grace. The author arrives at this conclusion, above all, by underlining oriental monasticism as the original context of the theology of divinization. Cassian was trained as a theologian and monk in this very ambience. All of the elements of the concept of divinization are present in the writings of Cassian and the two biblical models for the qšwsij of man – its creation of man in the image and likeness of God (Gen 1: 26-27) and the Transfiguration on Mount Tabor (Mt 17: 1-8; Mc 9: 2-8; Lc 9: 28-36) – are widely commented on by Cassian and form the basis of his theological and ascetical teaching. Cassian’s doctrine on grace, which is deeply penetrated by the concept of divinization, propounds the idea that, after original sin, the likeness of God in man is destroyed, but the image of God in man – reason, free will, and conscience – remains. The grace of God, perceived through the prism of divinization, in Cassian implies not a “resurrection” of the dead nature of man, but a strengthening of his relationship with God, a passage from the condition of “slave” to that of “friend”. This teaching, characterized as it is by a salvific optimism which is typically oriental, according to the author, should no longer be regarded as a form of semipelagianism. Rather, but with due qualification, it should be regarded as a valid and interesting way of speaking on the perennially difficult quaestio of the relationship between grace and free will.