by Scott D. Hendricks
Mental prayer is laborious and effortful, yet correspondingly fruitful, being the chiefest and highest activity of the mind, as it unites the mind with God, who is above all creatures. It purifies, illumines, and perfects the mind more than all the algebras, physics, metaphysics and all the other sciences of external philosophy. For it renders man spiritual and a contemplator of God, whereas they leave man at the level of nature — and the natural, nonspiritual man does not receive the gifts of the Spirit, for they are folly to him, as Paul says (1 Cor. 2: 14).
When you have brought your mind into the heart, do not let it simply observe and do nothing else; but finding discursive reason, through which we think, and compose works, and judge, and investigate, and read whole books without moving our lips, let your mind allow it to say nothing but this brief prayer, namely: “Lord Jesus Christ, Son of God, have mercy upon me.” However, this does not suffice; you must also arouse the will, so that you say this prayer with all you will, with all your power, and with all your love.
Let me speak more plainly. Discursive reason should only say the above mentioned prayer. Intuitive reason must pay attention only to the words of the prayer, especially to their meaning, remaining without form or shape, without imagining or attending to anything else, whether sensible or intelligible, internal or external, even though it be something good. Since God is beyond all things, both the sensible and the intelligible, and above them all, the mind, which seeks to be united with God through prayer, must go beyond all things, intelligible as well as sensible, and rise above them all, in order to succeed in attaining to this divine union. And your will must attach itself, through love, wholly to the words of the prayer. Thus, intuitive reason, discursive reason, and your will — these three parts of the soul — must be one, and the one three, for in this way man who is an image of the Holy Trinity, is united with the Prototype, as that great practicer and teacher of mental prayer and inner attention, the divine Gregory of Thessaloniki, has said. . . .
If you cannot practice this prayer continuously, because of your cares and distractions in the world, at least have one or two hours set aside, especially in the evening, and practice it withdrawn in a quiet and dark place.
~ St. Nicodemus the Hagiorite
Constantine Cavarnos, Modern Orthodox Saints vol. 3: St. Nicodemos the Hagiorite (Belmont: Institute for Byzantine and Modern Greek Studies, 1974), 142-145.