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.
Watchfulness cleanses the conscience and makes it lucid. Thus cleansed, it immediately shines like a light that has been uncovered, banishing such darkness. Once this darkness has been banished through constant and genuine watchfulness, the conscience then reveals things hidden from us.
The soul of all practices in the Lord is vigilance. Without vigilance, all these practices are fruitless. He who is desirous of saving himself must so establish himself that he might remain continuously vigilant toward himself, not only in solitude, but also under conditions of distraction, into which he is sometimes unwillingly drawn by circumstances.
The heart which is constantly guarded, and is not allowed to receive the forms, images and fantasies of the dark and evil spirits, is conditioned by nature to give birth from within itself to thoughts filled with light. For just as coal engenders a flame, or a flame lights a candle, so will God, who from our baptism dwells in our heart, kindle our mind to contemplation when He finds it free from the winds of evil and protected by the guarding of the intellect.
If a man only theorises about God, then he is helpless, utterly helpless, when confronted by an evil spirit. An evil spirit laughs at feeble worldly theorising. But as soon as a man begins to fast and to pray to God, the evil spirit becomes filled with inexpressible fear.
Almsgiving heals the soul's incensive power; fasting withers sensual desire; prayer purifies the intellect and prepares it for contemplation of created beings. For the Lord has given us commandments which correspond to the powers of the soul.
It seems to me that few people understand the extent of the cunning wickedness of these demons and the way in which they assist one another. I have known the demon of cowardice to fight and work together with that of listlessness. One comes to the aid of the other and reinforces him. The first brings fear and obduracy into the soul, the second produces darkness, negligence, blindness of heart and mind, and finally despair. Listlessness is a real trial for all those engaged in the spiritual struggle, but it becomes for them the ambassador of humility.
When someone is beginning the spiritual life, he should not study a lot, but instead watch himself and guard his thoughts. A strong person is the one who chews well, not the one who eats a lot.
The demons, murderers as they are, push us into sin. Or if they fail to do this, they get us to pass judgment on those who are sinning, so that they may defile us with the stain which we ourselves are condemning in another.
If anyone wants to drive out the demons, he must first subdue the passions, for he will banish the demon of the passion which he has mastered. For example, the devil accompanies anger; so it you control your anger, the devil of anger will be banished. And so it is with each of the passions.
The roof of any house stands upon the foundations and the rest of the structure. The foundations themselves are laid in order to carry the roof. This is both useful and necessary, for the roof cannot stand without the foundations and the foundations are absolutely useless without the roof-- no help to any living creature. In the same way the grace of God is preserved by the practice of the commandments, and the observance of these commandments is laid down like foundations through the gift of God. The grace of the Spirit cannot remain with us without the practice of the commandments, but the practice of the commandments is of no help or advantage to us without the grace of God.
Those who attend the divine service of the Orthodox Church must bear in mind that its purpose is to prepare us for the joyful service of God in heaven; that in serving God with the body, it is still more necessary to serve God with the soul and a pure heart; that in hearing divine service they must learn to serve God as those saints served him, whose lives, and works of faith, hope and love, we hear of during the service; that God should, above all, be served in deed and truth, and not only by words and the tongue.