Ancient monasticism is a phenomenon of remarkable complexity. The Desert Fathers were men and women who lived out the call to perfection left by Jesus in a very peculiar way. The abandonment of urban centers to go into the desert marks the transition from a public Christianity, characteristic of martyrs, to a private Christianity, characteristic of monks. In the desert, this space of solitude, silence, and self-denial, men and women lived in pursuit of their own improvement, whether in the pursuit of virtues or the abandonment of vices. For the Desert Fathers, passions are the field of combat in the pursuit of perfection, an ideal inherited from the witness of the martyrs. The theology of the Desert Fathers deals very deeply with themes related to the inner life. The recovery of the theology of these authors is justified by the relevance of their analysis of human passions, for which asceticism and prayer served as a remedy.