The passions are spiritual viruses of the soul—Saint Cassian provides the course of therapy for the divine cure.
Beyond simply depicting the way of life adopted by the illustrious elders of the desert, Saint John Cassian systematically presents the order of combat against the leading passions—spiritual diseases dragging the soul to every sin and eventually into Gehenna. The remedy: unremitting noetic prayer and watchfulness. For as Saint John describes, "It is not an external enemy we dread. Our foe is shut up within ourselves. An internal warfare is daily waged by us." The Institutes, therefore, is a manual of transformation renewing the soul in God.