Peter was first given the keys, but then he was allowed to fall into the sin of denying Christ; and so his pride was humbled by his fall. Do not be surprised, then, if after receiving the keys of spiritual knowledge you fall into various evil thoughts. Glorify our Lord, for He alone is wise: through setbacks of this kind He restrains the presumption that we tend to feel because of our advance in the knowledge of God. Trials and temptations are the reins whereby God in His providence restrains our human arrogance.
It is impossible for the soul to attain anything spiritual and pleasing to God, or to be free of inner sin, without guarding of the mind and purity of heart, in other words, without sobriety... If with God's help we gain something daily through our sobriety, we should take care not to enter into communication with other people without discrimination, lest we suffer loss through our converse with them and are led into temptation.
Having guarded ourselves against distractions and worries, let us turn our attention to our body on which mental vigilance is completely dependent. Human bodies differ widely from one another in strength and health. Some by their strength are like copper and iron; others are frail like grass. For this reason everyone should rule his body with great prudence, after exploring his physical powers. For a strong and healthy body, special fasts and vigils are suitable; they make it lighter, and give the mind a special wakefulness. A weak body should be strengthened by food and sleep according to one's physical needs, but on no account to satiety. Satiety is extremely harmful even for a weak body; it weakens it, and makes it susceptible to disease. Wise temperance of the stomach is a door to all the virtues. Restrain the stomach, and you will enter Paradise. But if you please and pamper your stomach, you will hurl yourself over the precipice of bodily impurity, into the fire of wrath and fury, you will coarsen and darken your mind, and in this way you will ruin your powers of attention and self-control, your sobriety and vigilance…
In order to remain in vigilance, it is necessary to guard the freshness and brightness of the mind with all care. The mind becomes darkened from imprudent use of food, drink and sleep, from much talking, from distraction and from worldly cares. Attend to yourselves, said the Lord, be on your guard and take care that your hearts are never weighed down, dulled and depressed by self-indulgence, overeating and drinking, or worldly cares and pleasures, lest that day (the day of Christ's dread judgment, the last day of the world) catch you unawares. For it will spring like a trap upon all who are living on the face of the earth. So watch and pray at all times for the strength to escape or survive all that is going to happen, and to stand before the Son of Man.
Patience reigns quietly and fruitfully in the life of the man who does not harm or endanger anyone, who is content with little and is obedient to the commandments of the Heavenly Father.
Some fast, live as solitaries without possessions, and pray that God will curb their nature; yet in spite of this, they allow themselves to slander, to reproach and judge their neighbors and ridicule them - and so the Divine help departs from them. They are left to themselves and are unable to find strength needed to counteract our nature's sinful suggestions. In a certain cenobitic monastery, there lived a hermit whose name was Timothy. One of the brethren in the cenobium became subject to temptation. When the abbot heard about this, he asked Timothy how the fallen brother should be treated. The hermit advised him that the seduced one should be expelled. And when they had sent him away, the fallen brother's temptation fell upon Timothy, so that he was in peril. Timothy began tearfully to groan for help and mercy from God. A voice came to him, 'Timothy, know that I have sent this temptation to you, because you disdained your brother in his hour of temptation.' One must deal with the members of Christ - Christians - with great care and circumspection. One must actually suffer with them in their weakness, cutting off only those who show no hope for restored health, lest they infect others with their ailments.
The Holy Fathers teach us how to become familiar with the Gospel, how to read it and how to understand it, what helps and what opposes its understanding. Therefore, at first you must devote more time to reading the Holy Fathers...
The humility which in due time and by God's grace, after many struggles and tears, is given by heaven to those who seek it is something incompararably stronger and higher than the sense of abasement felt by those who have lapsed from holiness. This higher humility is granted only to those who have attained true perfection and are no longer under the sway of sin.
The way to attain compunction is an attentive life. ‘The beginning of repentance comes from the fear of God and attention,’ as the holy martyr Boniface says.
If you refuse to accept suffering and dishonor, do not claim to be in a state of repentance because of your other virtues. For self-esteem and insensitivity can serve sin even under the cover of virtue.