John Cassian (360-435), the main western exponent of the monastic tradition, is the author of the two works, the Institutiones and the Collationes. Thanks to them it is possible to approach, through the word of a privileged and authoritative witness, the authentic tradition of Eastern monasticism. Making use of his personal encounters in Egypt, from hermitage to hermitage, with monks and abbots of the time, Cassiano offers a precious material for the understanding of primitive monastic life and illustrates the itinerary of perfection which the monk must strive for, addressing themes like prayer, friendship, discretion, humility, patience, and the dangers of vices.