It is customary in Orthodoxy, as in Western Christianity, to differentiate three levels of prayer: of the lips, of the mind, and of the heart.
This threefold distinction applies in particular to Jesus Prayer.
(1) To start with, the Jesus Prayer, like any other, is a prayer of the lips, an oral prayer.
(2) Yet prayer said only with the lips is obviously not true prayer. The mind, with its power of attention, also have to be involved. We may recall the admonition of John Climacus:
“Contain your mind within the words of prayer.”
So the Jesus Prayer grows gradually more inward. Yet we are not to be too quick in giving up the actual recitation of the words, whether spoken aloud or formed silently within us.
(3) Lastly, by the grace of God, the mind is united with the heart, so that our prayer becomes ‘prayer of the heart’ or, more precisely, ‘prayer of the mind in the heart‘.
By ‘heart’, in this context, Orthodox writers do not basically mean the emotions and feelings, but the spiritual centre of the total human being. The heart, as well as being a physical organ in our chest, shows symbolically the focal point of our personhood as created in the image and likeness of God.
The heart is thus the ground of our being, the root, and source of our inner truth. It involves the emotions, but more importantly, it is made up of our will, our reason, and also the higher visionary faculty known in Greek as the nous, whereby we comprehend the glory of God. In the words of Theophan the Recluse,
“The heart is the innermost self, or spirit. Here are located self- awareness, the conscience, the idea of God and of one’s complete dependence on Him, and all the eternal treasures of the spiritual life.”
As well as being the centre of our created personhood, the heart is also the point of encounter between each created person and the uncreated God. It is the gateway to self-transcendence, the place of divine indwelling.
“Within the heart are unfathomable depths” it is explained in the Spiritual Homilies attributed to St Macarius.
“…The heart is Christ’s palace: there Christ the King comes to take His rest, with the angels and the spirits of the saints, and He dwells there, walking within it and placing His Kingdom there .”
‘Prayer of the heart’, therefore, in Orthodox writings means not just ‘affective prayer’ in the Western sense but prayer of the entire human person, prayer in which body, soul and spirit are all involved.
Moreover, since the heart is the meeting place with God. According to St Paul’s, “prayer of the heart denotes not simply my prayer but the prayer of Christ in me.”