How can one say that a man has attained purity? - When he sees all men as being good, and when none appears to him to be unclean and defiled - then he is indeed pure in heart.
Our holy fathers have renounced all other spiritual work and concentrated wholly on this one doing, that is, on guarding the heart, convinced that, through this practice, they would easily attain every other virtue, whereas without it not a single virtue can be firmly established.
Trials are sent to some so as to take away past sins, to others so as to eradicate sins now being committed, and to yet others so as to forestall sins which may be committed in the future. These are distinct from the trials that arise in order to test men in the way Job was tested.
Trial is profitable for every man... Ascetic strugglers are tried, that they may add to their riches; the slothful are tried, that they may thereby guard themselves from what is harmful to them; the sleepy are tried, that they may be armed with wakefulness; those who are far away are tried, that they may draw nearer to God; those who are God's own are tried, that with boldness they may enter into His house. The son who is not trained will receive no profit from the riches of his father's house. For this reason, then, God first tries and afflicts, and thereafter reveals His gift. Glory be to our Master Jesus Christ Who brings us the sweetness of health by stringent medicines!
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.
Men who are leading a spiritual life see by the eyes of their heart how the devil lays his snares, how the angels guide us, and how the Lord, in His Sovereign power, allows the temptations, and how he comforts.
I thank Thee, O Keeper of faithful souls, that Thou hast shown us with Thine Own life an example of endurance in bearing all kinds of crosses. Give me the strength to follow the path of patience and humility in Thy footsteps, Christ my Lord. No matter what sorrow I will come across on this journey, I firmly trust that with Thy help, O Lord, I will overcome all obstacles. I understand now that no one can be freed from sorrows by avoiding them, but rather one should take care to endure them so as to conquer them...
I must tell you that annoying incidents are unavoidable in this life. Those who are experienced in the spiritual life say that such incidents can even bring profit to the soul. Through annoying incidents we come to recognize that we are impatient - and if we are impatient, that means we are proud. And this awareness should dispose us to self-reproach and repentance, and to asking mercy from the Lord in prayer. But without annoying incidents a man is inclined to conceit.
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.
A human being who does not endure courageously the unpleasant burdens of temptations, will never produce fruit worthy of the divine wine-press and eternal harvest, not even if one possesses all other virtues. For one is only perfected through zealously enduring both all the voluntary and involuntary afflictions.
Blessed are the pure in heart, for they shall see God. Everything we do, our every objective, must be undertaken for the sake of this purity of heart. This is why we take on loneliness, fasting, vigils, work, nakedness. For this we must practice the reading of the Scripture, together with all the other virtuous activities, and we do so to trap and to hold our hearts free of the harm of every dangerous passion and in order to rise step by step to the high point of love.