By St. Basil the Great
Our Lord, having fortified through fasting the flesh which He assumed for our sake, submitted to the attacks of the Devil therewith, both instructing us to anoint and train ourselves with fasting for the struggles that we must undergo amid temptations and affording the adversary a handle, so to speak, through hunger. For on account of the height of His Divinity He would have been inaccessible to the Devil, had He not submitted to human weakness through hunger. However, before He ascended back to Heaven, He tasted food, giving assurance of the true nature of His risen body.
Will you not give up fattening and gorging yourself? Will you allow your mind to waste away through lack of nourishment, because you take no thought for saving and life-giving teachings? Or do you not know that, just as in the case of a battle those who fight for one side cause the defeat of the other, so he who sides with the flesh prevails over the spirit, while he who aligns himself with the spirit brings his flesh into subjection? “[For] these [flesh and spirit] are contrary the one to the other.” Hence, if you wish to make your mind strong, tame your flesh through fasting. For this is what the Apostle says, that to the extent that our outward man perishes, our inward man is renewed; he also says: “When I am weak, then am I strong.”
Will you not disdain perishable foods? Will you not conceive a desire for the table in the Kingdom of Heaven, for which fasting here on earth is assuredly a preparation? Do you not know that by immoderate satiety you fatten for yourself the worm that torments? For who amid lavish feasting and perpetual delectation has become the partaker of any spiritual gift? Moses needed a second fast in order to receive the second set of laws. If the animals had not fasted along with the Ninevites, the Ninevites would not have escaped the threat of destruction. Whose carcasses fell in the wilderness? Were they not those of the people who demanded to eat meat? As long as they were content with manna and water from the rock, they overcame the Egyptians and journeyed through the sea; there was not a feeble one among their tribes.” But when they recalled the fleshpots and returned to Egypt in their desires, they did not see the Promised Land. Do you not fear their example? Do you not shudder at their gluttony, lest it exclude you from the good things for which we hope? But not even the wise Daniel would have seen visions, had he not rendered his soul more pellucid through fasting. For certain thick vapors are emitted from rich foods, which, like a dense cloud, prevent the illumination produced by the Holy Spirit from entering the mind. But if there is any food that is proper even to Angels, it is bread, as the Prophet says: “Man ate the bread of Angels” — not meat, nor wine, nor those items that are zealously sought after by those enslaved to their stomachs.
Fasting is a weapon against the army of demons. “[For] this kind can come forth by nothing, but by prayer and fasting.” So many are the benefits of fasting, whereas satiety is the beginning of lasciviousness. For sybaritism, inebriation, and all manner of rich foods immediately give rise to every kind of brutish wantonness. Hence, men become lecherous stallions on account of the frenzy wrought in the soul by self-indulgence. Perversions of nature arise from drunkards when they seek the feminine in the masculine and the masculine in the feminine. Fasting teaches moderation in conjugal relations, and, by chastising intemperance even in licit sexual activity, engenders abstinence by mutual agreement, so that married couples may devote themselves to prayer.