If a person swallows too much food, he is inviting impure thoughts. If he mortifies the stomach, he is creating pure thoughts. Often a lion if it is caressed becomes domesticated, whereas the more you coddle the body, the more it goes wild.
Sleep is a particular state of nature, an image of death, inactivity of the senses. Sleep is one, but, like desire, its sources and occasions are many; that is to say, it comes from nature, from food, from demons, or perhaps, sometimes, from extreme and prolonged fasting, through which the flesh is weakened and at last longs for the consolation of sleep.
Let us be sure, then, that God will not give spiritual gifts - the gifts of understanding, of faith, of love, of purity, of prophecy, of working wonders, of power over demons, of insight, of sight of the heavenly world, to him who has gambled with and made evil use, like the Prodigal Son, of the gifts of bodily health, honor, wealth, success among men or knowledge of this material world, or some other skill or capacity.
If someone is judged worthy to receive the gift of knowledge but allows his heart to be full of bitterness or rancor or aversion to another, it is as if he had been struck in the eye by a thornbush. That is why knowledge is no good without charity.
Just as over-drinking is a matter of habit, so too from habit comes over-sleeping. Therefore we must struggle with the question of sleep, especially in the early days of obedience, because a long-standing habit is difficult to cure.
The belly when filled with all kinds of food gives birth to seeds of wantonness, nor can the mind, when choked with the weight of food, keep the guidance and government of the thoughts. For not only is drunkenness with wine wont to intoxicate the mind, but excess of all kinds of food makes it weak and uncertain, and robs it of all its power of pure and clear contemplation. The cause of the overthrow and wantonness of Sodom was not drunkenness through wine, but fullness of bread. Hear the Lord rebuking Jerusalem through the prophet. 'For how did thy sister Sodom sin, except in that she ate her bread in fullness and abundance?' (Ezek. xvi. 49)
If you have received from God the gift of knowledge, however limited, beware of neglecting charity and temperance. They are virtues which radically purify the soul from passions and so open the way of knowledge continually.
It is not food that is evil but gluttony; not childbearing but fornication; not money but cupidity; not glory but vainglory. If this be so there is no evil in anything that is, except wrong use, which results from our mind neglecting to cultivate our nature (the powers of the soul, and their right direction).
If a man has some spiritual gift and feels compassion for those who do not have it, he preserves the gift because of his compassion. But a boastful man will lose it through succumbing to the temptations of boastfulness.
There is a difference, Dearly Beloved Brethren, between the delights of the body and those of the soul, that the delights of the body, when we do not possess them, awaken in us a great desire for them; but when we possess them and enjoy them to the full they straightway awaken in us a feeling of aversion. But spiritual delights work in the opposite way. While we do not possess them we regard them with dislike and aversion; but once we partake of them we begin to desire them, and the
more do we hunger for them. In one case the appetite pleases, the reality brings displeasure; in the other it is the appetite [that] displeases, the reality delights us more and more. In the one case appetite leads to fullness, and fullness to disgust; in the other appetite begets fullness, and fullness in turn begets appetite. For spiritual delights, when they fill the soul, increase in us a desire of them; and the more we savor them, the more do we come to know what we should eagerly love.
The night was not made to be spent entirely in sleep. Why did Jesus Christ pass so many nights amid the mountains, if not to instruct us by His example? It is during the night that all the plants respire, and it is then also that the soul of man is more penetrated with the dews falling from Heaven; and everything that has been scorched and burned during the day by the sun's fierce heat is refreshed and renewed during the night; and the tears we shed at night extinguish the fires of passion and quieten our guilty desires. Night heals the wounds of our soul and calms our griefs.
One should not ponder divine matters on a full stomach, say the ascetics. For the well-fed, even the most superficial secrets of the Trinity lie hidden.
Just as over-drinking is a matter of habit, so too from habit comes over-sleeping. Therefore we must struggle with the question of sleep, especially in the early days of obedience, because a long-standing habit is difficult to cure.