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.
Almost every sin is committed for the sake of sensual pleasure; and sensual pleasure is overcome by hardship and distress arising either voluntarily from repentance, or else involuntarily as a result of some salutary and providential reversal.
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.
If your heart has been softened either by repentance before God or by learning the boundless love of God towards you, do not be proud with those whose hearts are still hard. Remember how long your heart was hard and incorrigible. Seven brothers were ill in one hospital. One recovered from his illness and got up and rushed to serve his other brothers with brotherly love, to speed their recovery. Be like this brother. Consider all men to be your brothers, and sick brothers at that. And if you come to feel that God has given you better health than others, know that it is given through mercy, so in health you may serve your frailer brothers.
You must set about rooting out the very desire to have things pleasant, to get on well, to be contented. You must learn to like sadness, poverty, pain, hardship. You must learn to follow privately the Lord's bidding: not to speak empty words, not to adorn yourself, always to obey authority, not to look at a woman with desire, not to be angry and much else. For all these biddings are given us not in order for us to act as if they did not exist, but for us to follow: otherwise the Lord of mercy would not have burdened us with them. If any man will come after me, let him deny himself, He said (Matthew 16:24), thereby leaving it to each person's own will-if any man will-and to each person's endeavor: let him deny himself.
We truly love God and keep His commandments if we restrain ourselves from our pleasures. For he who still abandons himself to unlawful desires certainly does not love God, since he contradicts Him in his own intentions. . . Therefore, he loves God truly, whose mind is not conquered by consent to evil delight. For the more one takes pleasure in lower things, the more he is separated from heavenly love.
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.