Pre-eminence belongs to the Jesus prayer because it unites the soul with our Lord Jesus, and the Lord Jesus is the only door to union with God, which is the aim of prayer.
'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.
Grace abides in us from the time of our holy baptism; but, through our inattention, vanity and the wrong life we lead it is stifled, or buried. When a man resolves to lead a righteous life and is zealous for salvation, the fruit of his whole labor is, therefore, the restoration in force of this gift of grace. It comes to pass in a two-fold manner: first, this gift becomes revealed through many labors in following the commandments; insofar as a man succeeds in following the commandments, this gift becomes more radiant and brilliant. Secondly, it manifests and reveals itself through constant invocation of the Lord Jesus in prayer. The first method is powerful, but the second is more so, so that even the first method gains power through it. Thus, if we sincerely wish to open the seed of grace concealed in us, let us hasten to train ourselves in this latter exercise of the heart, and let us have only this work of prayer in our heart, without forms, without images, till it warms our heart and makes it burn with ineffable love of the Lord.
Without podvig there is altogether no true Christianity, that is to say, Orthodoxy. See what Christ, the First Ascetic, Himself clearly says; 'Whosoever will come after Me, let him deny himself, and take up his cross, and follow Me' (Mark 8:34). The true Christian, the Orthodox Christian, is only he who strives to emulate Christ in the bearing of the cross and is prepared to crucify himself in the Name of Christ. The holy Apostles clearly taught this. Thus the Apostle Peter writes: 'If when you do well and suffer for it, ye take it patiently, this is accepted with God. For even here unto were ye called, because Christ also suffered for us, leaving us an example, that we should follow his steps' (I Pet. 2:2-21). In precisely the same way the holy Apostle Paul says repeatedly in his epistles that all true Christians must be ascetics, and the ascetic labor of the Christian consists of crucifying himself for the sake of Christ: 'They that are Christians have crucified the flesh together with the passions and lusts' (Gal. 5:24). A favorite expression of St. Paul is that we must be crucified with Christ that we might rise with Him.
This prayer should never be absent from you: 'Lord Jesus Christ, Son and Logos of the living God, through the Theotokos and all the Saints, have mercy upon me, Thy sinful and unworthy servant.' (This is the actual Jesus Prayer: 'O LORD JESUS CHRIST, SON OF GOD, HAVE MERCY UPON ME, A SINNER.') Always say this prayer both with your mouth and with your mind, day and night, wherever you may be, whether eating, walking, working, or sitting. Always meditate on it, as it benefits you a great deal, frees you here from every evil, delivers you there from eternal Hell, and renders you worthy of going to Paradise, our heavenly country.
The practice of the prayer of Jesus holy David, or more accurately the Holy Spirit by the mouth of David, offers to all Christians without exception: 'The kings of the earth and all people, princes and all judges of the earth, young men and maidens - let elders with the young praise the name of the Lord, for His name alone is exalted (PS. 148:11-13).' A literal understanding of the states enumerated here would be perfectly permissible, but their essential meaning is spiritual.
In the grim struggle with the invisible enemies of our salvation, the supreme weapon is the prayer of Jesus. `All the nations' - the vociferous and wily demons are called nations - `surround me,' says David, `and in the name of the Lord I repulsed them. They encircled and surrounded me like bees, and they burnt like fire among thorns; and in the name of the Lord I repulsed them' (Ps. 117:10-12). With the name of Jesus flog the foes, because there is no stronger weapon in heaven or earth.
Whenever we are filled with evil thoughts, we should throw the invocation of our Lord Jesus Christ in their midst. Then, as experience has taught us, we shall see them instantly dispersed like smoke in air. Once the intellect is left to itself again, we can renew our constant attentiveness and our invocation. Whenever we are distracted, we should act in this way.
What should one do so that the mind might be constantly occupied with God? If we do not acquire the three following virtues: love for God and men, continence, and the Prayer of Jesus, then our mind cannot be completely occupied with God. For love makes anger meek, continence weakens fleshly desire, and prayer draws the mind away from thoughts and banishes every hatred and high-mindedness.
Blessed are those who acquire the habit of this heavenly practice (unceasing prayer in the name of Jesus), for by it they overcome every temptation of the evil demons, as David overcame the proud Goliath. It extinguishes the unruly lusts of the flesh, as the three men extinguished the flames of the furnace. This practice of inner prayer tames passions as Daniel tamed the wild beasts. By it the dew of the Holy Spirit is brought down upon the heart, as Elijah brought down rain on Mount Carmel.
Brethren, let us also occupy yourselves with noetic prayer… and seeking God’s mercy, cry out with a humble heart from morning till night and if possible all night long, saying constantly: 'Lord Jesus Christ, Son of God, have mercy on us.'
The incessant invocation of God's name is a medicine which mortifies not just the passions, but even their influence. Just as the physician puts medications or dressings on a wound that it might be healed, without the patient even knowing the manner of their operation, so also the name of God, when we invoke it, mortifies all passions, though we do not know how that happens.
Moreover, bear in mind the method of prayer – how it is possible to pray without ceasing, namely by praying in the mind. And this we can always do if we so wish. For when we sit down to work with our hands, when we walk, when we eat, when we drink we can always pray mentally and practice this mental prayer – the true prayer pleasing to God.
Man's chief aim should be to find God. In finding God, he finds true happiness. The interior prayer we have been discussing [the Prayer of Jesus] leads man to Him. We can never thank God sufficiently for revealing Himself to us. We can never even thank Him enough for the other goods He bestows upon us. God need not have created man: He had hosts of angels. Yet He created man and countless marvelous things for him.
Let us work with the body and pray with the soul. Let our outer man perform his bodily tasks, and let the inner man be entirely dedicated to the service of God, never abandoning this spiritual practice of mental prayer, as Jesus, God and Man, commanded us, saying: 'But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret' (Matthew 6:6).The closet of the soul is the body; our doors are the five bodily senses. The soul enters its closet when the mind does not wander hither and thither, roaming among things and affairs of the world, but stays within, in our heart. Our senses become closed and remain closed when we do not let them be attached to external sensory things, and in this way our mind remains free from every worldly attachment, and by secret mental prayer unites with God its Father. 'And thy Father which seeth in secret shall reward thee openly,' adds the Lord. God who knows all secret things sees mental prayer and rewards it openly with great gifts. For that prayer is true and perfect which fills the soul with Divine grace and spiritual gifts. As chrism perfumes the jar the more strongly the tighter it is closed, so prayer, the more fast it is imprisoned in the heart, abounds the more in Divine grace.
Please put this commandment into practice. Cultivate love towards the Person of Christ to such an extent that, when you pronounce His name, tears fall from your eyes. Your heart must really burn. Then He will become your teacher. He will be your Guide, your Brother, your Father, and your Elder.