Unless curbed by the fear of God that accompanies the practice of the virtues, spiritual knowledge leads to vanity; for it encourages the person puffed up by it to regard as his own what has merely been lent to him, and to use his borrowed intelligence to win praise for himself. But when his practice of the virtues increases concomitantly with his longing for God, and he does not arrogate to himself more spiritual knowledge than is needed for the task in hand, then he is made humble, reduced to himself by principles which are beyond his capacity.
When your brother is disturbed and reacts to what you say to him, control your tongue lest you speak even one word in wrath and do not allow yourself to be arrogant concerning him in your heart but remember that he is your brother, a member of Christ and an image of God, influenced by the common enemy. Be merciful and show pity on him because it is possible that the devil through your wrath, will capture his soul and mortify it in resentment and thus, through your carelessness, the soul for whom Christ died is lost (1 Cor. 5:11).
St. John Climacus was asked if there are reliable signs by which it's possible to know whether a soul is drawing near to God or moving away from Him. After all, regarding ordinary things there are clear signs as to whether they're good or not. When, for instance, cabbage, meat or fish begins to rot, it's easy to notice it, since the rotting object begins to give off a foul odor, the color and taste change, and its external appearance witnesses to its deterioration. Well, and what about the soul? After all, it's bodiless and can't give off a bad smell or change its appearance. To this question the Holy Father replies, 'A sure sign of the deadening of the soul is the avoidance of church services.'
Solitude offers us an excellent opportunity for calming our passions and giving our reason time to remove them thoroughly from our soul. For just as wild animals can be soothed by being stroked, so all our anger, fear and stress, which poison and disrupt our soul, can be soothed by an atmosphere of peace where the freedom from constant disturbance ensures that our soul can be brought more easily under the power of reason.