The following excerpt is from an anonymous 1851 manuscript called The Watchful Mind. It was penned by an unknown monk on Mount Athos, the “Holy Mountain”, the continuous home of the “hesychastic” contemplative Christian prayer tradition for more than a thousand years.
“Beloved, when you wish to pray noetically from your depths, let the prayer of your heart imitate the sound of the cicada. When the cicada chirps, it does so in two ways. At first, it softly chirps five to ten times, but then its ending chirps are more pronounced, drawn out, and melodic. And so, beloved when you pray noetically within your heart, pray in the following manner: First say, “Lord Jesus Christ, Son of God, have mercy on me” about ten times, forcefully from your heart and clearly with your intellect from your depths, one time with each breath. Restrain your breath a little each time you say the prayer as your heart meditates from its depth on the words. Once you have said the prayer in this fashion ten times or more until that place within you has become warm where you meditate upon the prayer, then say the prayer more forcefully, with greater tension and forcefulness of heart, just as the cicada ends its song with a more pronounced and melodic voice.
This prayer, which is referred to principally as noetic prayer, is also called prayer of the heart and watchful prayer. When you say the prayer with your intellect and repeat it mystically within you in stillness, using your inner voice, it is referred to as noetic prayer. When you say the prayer from the depths of your heart with great tension and inner force, then it is referred to as prayer of the heart. It is referred to as watchful prayer when, because of your prayer or because of the infinite goodness of God, the grace of the Holy Spirit visits your soul and touches your heart, or you are granted a divine vision, upon which your mind’s eye becomes watchful and fixed.
When you practice noetic prayer and reverently repeat it as you should, and the grace of the Holy Spirit visits your soul, then the name of Christ that you are meditating upon with your intellect becomes greatly consoling and sweet to your mind and soul, so much that you could never repeat it enough.
When you practice prayer of the heart and the grace of God touches your heart (that is, when your heart happens upon it), causing it to conceive compunction, as the Lady Theotokos [“God Bearer”, the Virgin Mary] conceived the Word of God by the Holy Spirit, then the name of divine Jesus, and all of Holy Scripture, becomes ineffable sweetness to the heart, and every spiritual notion of the heart (if I may put it this way) becomes a sweet flowing river of divine compunction that sweetens the heart and wondrously makes it fervent in eros and love for it Creator and God.
Sometimes, when you practice prayer of the heart with pain of an enfeebled heart and with sorrow of a humbled soul, then your soul clearly feels the consolation and visitation of the Lord. This is what the prophet says: “The Lord is near those who are brokenhearted.” The Lord invisibly draws near you when you crush your heart with the prayer, as we said, in order to show you some mystical revelation. He shows you some vision in order to make you more fervent in the spiritual work of your heart.
And so, beloved, when, by the grace of Christ, your soul beholds some vision and is filled with compunction because of your prayer, then you understand that watchful prayer is nothing other than divine grace; it is the noetic and divine vision your mind beholds, your intellect firmly fixed upon, and your soul watches. And that the divine grace of the Holy Spirit visited your soul, gently touched your heart, and ineffably sweetened your mind, only you can understand and comprehend within yourself, because compunction ceaselessly from your heart as from an ever-flowing spring, while your mind experiences an inexpressible sweetness and your soul consolation. At that moment your soul possesses some spiritual boldness and mystically supplicates God, its Fashioner and Creator saying, “Remember me, Oh Lord, in your Kingdom,” or some other verse of Holy Scripture.
This holy and pure supplication that takes place within the soul has such power that it penetrates the heavens and reaches the throne of the Holy Trinity, before whom it stands like sweet-smelling and fragrant incense. The prophet said about this prayer, “Let my prayer arise as incense before you.” The God in Trinity receives this holy supplication in an inexpressible and wondrous manner, and the supplication in turn receives the fruit of the Holy Spirit. This fruit, received reverently and modestly, is offered and sent to the soul as a priceless and heavenly gift from the God of all as a pledge of the future kingdom and adoption. The soul that receives the heavenly and divine fruit of the Holy Spirit because of its supplication, that is, from pure prayer, acquires divine love, spiritual joy, peace of heart, and great patience during the hardships and temptations of this age, excellence and goodness in everything, unwavering faith, Christ’s meekness, and passion-killing self-control. All of these are called “fruit of the Holy Spirit.” To our God be glory and power unto ages of ages. Amen.” ~ The Watchful Mind, pp 123-125.