Do not trust to abstinence not to fall. One who had never eaten was cast from heaven.
Certain learned men have well defined renunciation, by saying that it is hostility to the body and a fight against the stomach.
With beginners falls usually occur by reason of luxury; with intermediates because of haughtiness as well as from the same cause which leads to the fall of beginners; and with those approaching perfection, solely from judging their neighbour.
(…) Do not expect to confute the demon of fornication by arguing with him; for with nature on his side, he has the best of the argument.
He who has resolved to contend with his flesh and conquer it himself struggles in vain. For unless the Lord destroys the house of the flesh and builds the house of the soul, the man who desires to destroy it has watched and fasted in vain.
Offer to the Lord the weakness of your nature, fully acknowledging your own incapacity, and you will receive imperceptibly the gift of chastity.
—St. John Climacus, The Ladder of Divine Ascent