Η ΑΔΙΑΛΕΙΠΤΗ ΠΡΟΣΕΥΧΗ. Jesus Prayer - Thoughts from the Fathers

For Eastern Orthodox Christians the Jesus Prayer is one prayer that has been recognized over the centuries to be especially powerful.  It is much more than the recitation of a few words over and over.  It is a means of joining mystically with God.

"The action of the Jesus Prayer is always hidden by the greatest mysteries.  It does not consist merely in speaking the words, 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' but reaches the heart and mysteriously settles there. Through this prayer we enter into relationship with the Lord Jesus Christ, we become accustomed to Him, we merge with Him into one whole. This prayer fills the soul with calm and joy amidst the most difficut trials, in the midst of every oppressions and human vanity."  St. Barsanuphius of Optima

It is a prayer which demands and aids in our focusing of the attention of our mind on our sinful state and our need for forgiveness by God.

"The essential properties of this prayer should be: attention ,the enclosure of the mind in the words of the prayer, extreme unhurriedness in pronouncing it, and contrition of spirit.... In the case of the Jesus Prayer, the mind is concentrated on a single thought: the thought of the sinner's forgiveness by Jesus."  St. Ignatius Brianchaninov

Through the practice of this prayer which involves many repetitions each day we are aided in developing of humility calling into us the Holy Spirit to transform our inner being into one of divine joy.

If we want to realize and know the truth... let our aim be to make the energy of prayer alone active in our hearts, for it brings warmth and joy to the spirit, and sets the heart alight with an effable love for God and man.  It is on account of this that humility and contrition flow richly from prayer. For Prayer in the beginners is the unceasing noetic activity of the Holy Spirit.  To start with it rises like a fire of joy from the heart; in the end it is like light made fragrant by Divine Energy.  St. Gregory of Sinai

For me personally, the Jesus Prayer has transformed my life.  For many years I denied my sinfulness, but now it is ever before me. I now struggle with contrition, but with hope and an inward burning zeal.  I ask for your prayers.
http://orthodoxwayoflife.blogspot.com/2010/04/jesus-prayer-thoughts-from-fathers.html

Other Fathers from Writings fro the Philokalia On Prayer of the Heart

The beginning of every action pleasing to God is calling with faith on the life-saving name of our Lord Jesus Christ, as He Himself said: ‘Without me ye can do nothing (John 15:5), together with the peace and love which accompany this calling. Peace, for as the Apostle says: ‘I will therefore that men pray...without wrath and doubting’ (1Tim 2:8); love for ‘God is love; and he that dwelleth in love dwelleth in love dwelleth in God and God in him’ (1John 4:6). These two, peace and love, not only make the prayer propitious, but are themselves reborn and shine forth from this prayer, like inseparable Divine rays.
Callistus and Ignatius p 167-168

The great Chrysostom also says: ‘I implore you, brethren, never to break or despise the rule of tis prayer.’ And a little further: ‘A monk when he eats, drinks, sits, officiates, travels or does an other thing just continually cry: “Lord, Jesus Christ, Son of God, have mercy upon me!” so that the name of the Lord Jesus, descending into the depths of the heart, should subdue the serpent ruling over the inner pastures and bring life and salvation to the soul. He should always live with the name of the Lord Jesus, so that the heart absorbs the Lord and the Lord the heart, and the two become one.’ And again: ‘Do not estrange your heart from God, but abide in Him and always guard your heart by remembering our Lord Jesus Christ, until the name of the Lord becomes rooted in the heart and it ceases to think of anything else. May Christ be glorified in you.
Callistus and Ignatius p 194

Saint Paul said in one of his Epistles: “If thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation” (Rom 10:9-10). And again: “No man can say that Jesus is the Lord but by the Holy Spirit” (1 Cor 12:3). But the Holy Spirit he means when the heart is made active by the Holy Spirit and prays through Him: which is the attribute of those who have succeeded in their work and have been actively enriched by Christ dwelling in them. St. Diadochus expresses the same idea: “When by remembrance of God we close all the exits of our mind it has need of some obligatory work to satisfy its restlessness. The only thing it should be given is the sacred name of our Lord Jesus; let this wholly satisfy its zeal to attain the aim it has set itself. But it should be realized that , as the Apostle says: “No man can say that Jesus is the Lord, but by the Holy Spirit.” On our side it is demanded that the aforesaid prayer (Lord Jesus Christ and so on) should be uttered by a mind imprisoned within itself and should be repeated continuously in its fastnesses, so that it may not stray into any foreign dreamings. Those who mentally keep this holy and most glorious Name unceasingly in the depth of their heart, can see too the light of their mind (clarity of thought of a definite consciousness of all inner movements)” And again: “When this wonderful Name is kept in thought thought with intense care it very effectively scorches every filth which appears in the soul. “For our God is a consuming fire” scorching all evil says the Apostle (Heb. 12:29). Out of the fire the Lord finally brings the soul into a great love for His glory. For the glorious and most coveted Name, becoming established in the warmth of the heart through the mind’s remembrance of it, gives birth to the habit of unhampered love of His goodness, since nothing then remains to hinder this. This is the precious pearl which a man acquires having sold his possessions and rejoices greatly in acquiring Him.” (Chap 59). Hesychius speaks thus of it: “When after death the soul soars into the air to the gates of heaven, it will not be shamed by its enemies even there, if it has Christ with it and for it; but then, as now, it will boldly ‘speak with the enemies in the gate’ (Ps cxxvii. 5). So long as it does not grow weary of calling to our Lord Jesus Christ, the Son of God day and night till death itself, He will avenge it speedily according to His true promise, given in the parable of the unjust judge: “I tell you that he will avenge them speedily” (Luke 18:8) both in this life and after leaving the body” (chap 149) Saint John of the Ladder says: “Flog the foes with the name of Jesus; for there s no stronger weapon against them either in heaven or on earth” (Chap 21)...
Callistus & Ignatius 224-225

And so every time it happens that wicked thoughts multiply in us. let us throw among them the invocation of our Lord Jesus Christ; and we shall at once see them dispersed like smoke in the air, as experience teaches. And then, when the mind is left free (without confusing thoughts), let us start again with constant attention and invocation. So let us act every tie we suffer such temptation.
Hesychius of Jerusalem p 298

Power of Name
The great David, experienced in deeds, says to the Lord: “Because of his strength will I wait upon thee’ (Ps lix. 9) (that is, I turn to Thee for help). Even so it is the help of the Lord that preserves in us the power for silence of heart and mind––that silence out of which all the virtues arise. For the Lord gives us commands and He drives away from us accursed sloth. And if we constantly call on Him He defends us against unseemly forgetfulness, which is above all destructive of our peace of heart, as water is of fire. therefore, brother, do not from negligence sleep unto death, but scourge thy enemies with the name of Jesus; and as some wise man (st. Gregory the Theologian) has said: “Let His most sweet name be joined to thy breath; and then shalt thou know the profit of silence.”
Hesychius of Jerusalem p 298-299

Forgetfulness naturally extinguishes the guarding of the mind, as water extinguishes fire. But constant prayer to Jesus with unflagging sobriety, just as a small lantern needs a candle (perhaps as a lantern needs windless calm to burn like a candle.)
Hesychius of Jerusalem p 299

Great care should be taken to preserve that which is precious. But for us only one thing is truly precious––that which preserves us from all evil, both sensory and mental. And this is guarding the mind with invocation of Jesus Christ, that is, always looking into the depths of our heart and keeping out thought constantly silent. I will say even more;––we should strive to be empty even of thoughts which appear to come from the right, and in general all thoughts, lest thieves are concealed behind them. But however painful the labor of patiently remaining in the heart, relief is nearby.
Hesychius of Jerusalem p 299

Prayer to Jesus, practices with sobriety from the deepest thoughts of the heart, destroys the thoughts which have insinuated themselves into our heart against our will and are dwelling therein.
Hesychius of Jerusalem p 306

As it is impossible to cross the expanse of the sea without a large ship, so without calling on Jesus Christ it is impossible to banish from the soul the suggestion of a wicked thought.
Hesychius of Jerusalem p 307

When, empowered by Jesus Christ, we begin to press forward in firmly established sobriety; then, first, there appears in our mind a lamp, as it were, which the hand of our mind holds aloft to guide our mental steps; thereafter comes a full moon, circling in the sky of the heart, and , at last, like the sun, comes Jesus, radiant with truth like the sun, that is, both revealing Himself and illuminating contemplation with His all-brilliant rays.
Hesychius of Jerusalem p 313

http://www.orthodoxprayer.org/Jesus%20Prayer/Jesus%20Prayer/%20Implication%20Using%20Name.html