One should nourish the soul with the word of God: for the word of God, as St. Gregory the Theologian says, is angelic bread, by which are nourished souls who hunger for God. Most of all, one should occupy oneself with reading the New Testament and the Psalter, which one should do standing up. From this there occurs an enlightenment in the mind, which is in the mind, which is changed by a Divine change.
Those who have truly decided to serve the Lord God must train themselves in the remembrance of God and in unceasing prayer to Jesus Christ, saying mentally: 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Through such activity, and by guarding oneself from distraction, and with the preservation of peace in one's conscience, it is possible to draw near to God and to be united with Him. For, according to the words of St. Isaac the Syrian, 'Except for unceasing prayer we cannot draw near to God.'
To wage war only with the sins that make their appearance as actual deeds would be just as unsuccessful as cutting down weeds in a garden instead of digging them up at the root and throwing them out. Sins appear as inevitable outgrowths from their roots, the passions of the soul.
Pray before your body takes rest on your bed... If you are tempted, make the Sign (of the Cross) on your forehead reverently… for this is a known and tested weapon against the Devil.
It is more serious to lose hope than to sin. The traitor Judas was a defeatist, inexperienced in spiritual warfare; as a result he was reduced to despair by the enemy's onslaught, and he went and hanged himself. Peter, on the other hand, was a firm rock: although brought down by a terrible fall, yet because of his experience in spiritual warfare he was not broken by despair, but leaping up he shed bitter tears from a contrite and humiliated heart. And as soon as our enemy saw them, he recoiled as if his eyes had been burnt by searing flames, and he took flight...
'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Let your attention and instruction be centered on this. Walking, eating, standing in church before the beginning of the service, continue with the prayer; on entering and departing keep this prayer on your lips and within your heart. In such a manner, with the invocation of the Name of God you will find peace, you will attain to purity of spirit and body; and the Holy Spirit, the Origin of all good, will make for Himself a dwelling within you and will guide you in all piety and purity.
This is the mark of Christianity--however much a man toils, and however many righteousnesses he performs, to feel that he has done nothing, and in fasting to say, 'This is not fasting,' and in praying, 'This is not prayer,' and in perseverance at prayer, 'I have shown no perseverance; I am only just beginning to practice and to take pains;' and even if he is righteous before God, he should say, 'I am not righteous, not I; I do not take pains, but only make a beginning every day.'
Faith is an eye that enlightens every conscience, and imparts understanding; for the Prophet saith, And if ye believe not, ye shall not understand (Is. vii, 9).
Thus should we weep for the forgiveness of our sins. The words of the bearer of the purple should convince us of this: 'Going they went and wept, casting their seed; but coming they shall come with joyfulness, carrying their sheaves (Ps. 125:6);' as well as the words of St. Isaac the Syrian: 'Moisten your cheeks with the tears of your eyes, that the Holy Spirit may abide in you, and cleanse the filth of your malice. Move your lord with your tears, that He may help you' (homily 68).
One must train oneself in generous patience, so as to endure without complaint all that happens to us. We will possess patience when we accept everything that happens to us, both what is joyful and what is sad, without distinction, as from the hand of God.
Suppose you have ordered yourself not to eat fish; you will find that the enemy continually makes you long to eat it. You are filled with an uncontrollable desire for the thing that is forbidden. In this way you can see how Adam's fall typifies what happens to all of us. Because he was told not to eat from a particular tree, he felt irresistibly attracted to the one thing that was forbidden him.
In patience is the assembly of all the virtues by which our souls are saved, as St. Ephraim says: He who acquires patience touches on every virtue; for he rejoices in sorrows, is well tested in misfortunes, is glad in perils, is ready for obedience, is filled with love, gives praise when provoked, is humble when reproached, is unwavering in misfortunes.
Because the nous can get tired by the reciting of all the words of the Jesus Prayer, it is necessary to make it shorter: 'Lord Jesus Christ, have mercy on me.' Or, 'Lord have mercy on me.' Or, 'Lord Jesus.' As the Christian progresses in the work of the Jesus Prayer, he can decrease the words. He can even sometimes insist on the word 'Jesus,' which he says repeatedly (Jesus, Jesus, Jesus, my Jesus)--a wave of calmness and joy rises in him. He should remain in this sweetness which appears and not stop the prayer, even if his usual rule of prayer is finished. He should seize and keep this warmth of his heart and take advantage of this gift of God! For it is a great gift which God sends from on high. The warmth of the heart helps the nous effectively to be fixed on the words of the Jesus Prayer ... If one wants to spend all day in prayer, he should follow the recommendation of the Holy Fathers. He should pray for an hour, read for an hour and then again spend an hour in prayer. When he is engaged in manual work too, he should try to say the Jesus Prayer.
'Then the devil left Him, and angels came and ministered to Him' (Matthew 4:11). It does not say that the angels were with our Lord during the actual time when He was being tempted. In the same way, when we are being tempted, God's angels for a time withdraw a little. Then, after the departure of those tempting us, they come and minister to us with divine intellections, giving us support, illumination, compunction, encouragement, patient endurance, joyfulness, and everything that saves and strengthens and renews our exhausted soul. As Nathaniel was told, 'You will see the angels ascending and descending upon the Son of man' (John 1:51); in other words, the ministry and assistance of the angels will be given generously to mankind.