1. Watchfulness is a spiritual method which, if sedulously practiced over a long period, completely frees us: with God’s help from impassioned thoughts, impassioned words and evil actions. It leads, in so far as this is possible, to a sure knowledge of the inapprehensible God, and helps us to penetrate the divine and hidden mysteries. It enables us to fulfill every divine commandment in the Old and New Testaments and bestows upon us every blessing of the age to come. It is, in the true sense, purity of heart, a state blessed by Christ when He says: ‘Blessed are the pure in heart, for they shall see God’ (Matt. 5:8); and one which, because of its spiritual nobility and beauty – or, rather, because of our negligence – is now extremely rare among monks. Because this is its nature, watchfulness is to be bought only at a great price. But once established in us, it guides us to a true and holy way of life. It teaches us how to activate the three aspects of our soul correctly, and how to keep a firm guard over the senses. It promotes the daily growth of the four principal virtues, and is the basis of our contemplation.
2. The great lawgiver Moses – or, rather, the Holy Spirit -indicates the pure, comprehensive and ennobling character of this virtue, and teaches us how to acquire and perfect ft, when he says: ‘Be attentive to yourself, lest there arise in your heart a secret thing which is an iniquity’ (Deut. 15:9. LXX). Here the phrase ‘a secret thing’ refers to the first appearance of an evil thought. This the Fathers call a provocation introduced into the heart by the devil. As soon as this thought appears in. our intellect, our own thoughts chase after it and enter into impassioned intercourse with it.
3. Watchfulness is a way embracing every virtue, every commandment. It is the heart’s stillness and, when free from mental images, it is the guarding of the intellect.
4. Just as a man blind from birth does not see the sun’s light, so one who fails to pursue watchfulness does not see the rich radiance of divine grace. He cannot free himself from evil thoughts, words and actions, and because of these thoughts and actions he will not be able freely to pass the lords of hell when he dies.
5. Attentiveness is the heart’s stillness, unbroken by any thought. In this stillness the heart breathes and invokes, endlessly and without ceasing, only Jesus Christ who is the Son of God and Himself God. It confesses Him who alone has power to forgive our sins, and with His aid it courageously faces its enemies. Through this invocation enfolded continually in Christ, who secretly divines all hearts, the soul does everything it can to keep its sweetness and its inner struggle hidden from men, so that the devil, coming upon it surreptitiously, does not lead it into evil and destroy its precious work.
6. Watchfulness is a continual fixing and. halting of thought at the entrance to the heart. In this way predatory and murderous thoughts are marked down as they approach and what they say and do is noted; and we can see in what specious and delusive form the demons are trying to deceive the intellect. If we are conscientious in this, we can gain much experience and knowledge of spiritual warfare.
7. In one who is attempting to dam up the source of evil thoughts and actions, continuity of watchful attention in the intellect fat produced by fear of hell and fear of God, by God’s withdrawals from the soul, and by the advent of trials which chasten and instruct. For these withdrawals and unexpected trials help us to correct our life, especially when, having once experienced the tranquility of watchfulness, we neglect it. Continuity of attention produces inner stability; inner stability produces a natural intensification of watchfulness; and this intensification gradually and in due measure gives contemplative insight into spiritual warfare. This in its turn is succeeded by persistence in the Jesus Prayer and by the state that Jesus confers in which the intellect, free from all images, enjoys complete quietude.
8. When the mind, taking refuge in Christ and calling upon Him, stands firm and repels its unseen enemies, like a wild beast facing a pack of hounds from a good position of defense, then it inwardly anticipates their inner ambuscades well in advance. Through continually invoking Jesus the peacemaker against them, it remains invulnerable.
Excerpt from the Philokalia – St. Hesychios the Priest “On Watchfulness and Holiness”