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 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.
Fear is a rehearsing of danger beforehand; or again, fear is a trembling sensation of the heart, alarmed and troubled by unknown misfortunes. Fear is a loss of assurance.
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 soul that is given over to the will of God fears nothing: neither thunder nor thieves nor any such thing. Whatever may come, 'Such is God's pleasure,' she says. If she falls sick she thinks, 'This means that I need sickness, or God would not have sent it.'
Apostolic teaching, Beloved, exhorts us that we put off the old man with his deeds (Eph. iv. 22; Col. iii. 9), and renew ourselves from day to day by a holy manner of life. For if we are the temple of God, and if the Holy Spirit is a Dweller in our souls, as the Apostle says: You are the temple of the living God (II Cor. vi. 16); we must then strive with all vigilance that the dwelling of our heart be not unworthy of so great a Guest.
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.
Continually take careful note of your inner intention: watch carefully which way it inclines, and discover whether it is for God and the sake of goodness itself and the benefit of your soul...
Watch constantly, learning to understand God's law, for this warms the heart with heavenly fire. Guard your lips from the idle word, or empty talk, lest the heart gets used to evil words.
No Christian believing rightly in God should ever be off his guard. He should always be on the look-out for temptation, so that when it comes he will not be surprised or disturbed, but will gladly endure the toil and affliction it causes, and so will understand what he is saying when he chants with the prophet: 'Prove me, O Lord, and try me' (Ps. 26:2 LXX). For the prophet did not say, 'Thy correction has destroyed me,' but, 'it has upheld me to the end' (Ps. 18:35 LXX).
Smoke from wood kindling a fire troubles the eyes; but then the fire gives them light and gladdens them. Similarly, unceasing attentiveness is irksome; but when, invoked in prayer, Jesus draws near, He illumines the heart; for remembrance of Him confers on us spiritual enlightenment and the highest of all blessings.
We must vigilantly guard our heart from unfitting thoughts and impressions, according to the word of the writer of Proverbs: ‘Keep thine heart with the utmost care; for out of these are the issues of life,’ (Proverbs 4:23).