The Desert Fathers: Sayings of the Early Christian Monks - 5. Lust (2/4/41)

Gerontius of Petra said, 'Many people who are tempted by pleasures of the flesh do not sin with the body but lust with the mind; they keep their bodily virginity but lust in their heart. It is better then, beloved, to do what is written, "Let everyone keep a close guard upon his heart" (Prov. 4:23).'