Bodily fasting alone is not enough to bring about perfect self-restraint and true purity; it must be accompanied by contrition of heart, intense prayer to God, frequent meditation on the Scriptures, toil and manual labor. These are able to check the restless impulses of the soul and to recall it from its shameful fantasies. Humility of soul helps more than everything else, however, and without it no one can overcome unchastity or any other sin. In the first place, then, we must take the utmost care to guard the heart from base thoughts, for, according to the Lord, ‘out of the heart proceed evil thoughts, murders, adulteries, unchastity’ and so on (Matt.15:19).
We are told to fast not only to mortify our body, but also to keep our intellect watchful, so that it will not be obscured because of the amount of food we have eaten and thus be unable to guard its thoughts. We must not therefore expend all our effort in bodily fasting; we must also give attention to our thoughts and to spiritual meditation, since otherwise we will not be able to advance to the heights of true purity and chastity. As our Lord has said, we should ‘cleanse first the inside of the cup and plate, so that their outside may also be clean’ (Matt. 23:26).
If we are really eager, as the Apostle puts it, to ‘struggle lawfully’ and to ‘be crowned’ (2 Tim. 2:5) for overcoming the impure spirit of unchastity, we should not trust in our own strength arid ascetic practice, but in the help of our Master, God. No one ceases to be attacked by this demon until he truly believes that he will be healed and reach the heights of purity not through his own effort and labor, but through the aid and protection of God. For such a victory is beyond man’s natural powers. Indeed, he who has trampled down the pleasures and provocations of the flesh is in a certain sense outside the body. Thus, no one can soar to this high and heavenly prize of holiness on his own wings and learn to imitate the angels, unless the grace of God leads him upwards from this earthly mire. (On the Eight Vices)