The Chief Thing in Prayer is the Arising of Reverent Feelings

To stand before an icon and make prostrations is not yet prayer, but only an aspect of prayer; to read prayers—from memory, from a book, or to listen to them—is not yet prayer, but only an instrument of prayer or a means of its expression and awakening. Prayer itself is the arising in our heart, one after another, of reverent feelings toward God: feelings of self-abasement, surrender, thanksgiving, glorification, petition, contrition, obedience to God’s will, earnest turning to Him, and the like.

All our care here should be that during our prayer these and such feelings fill our soul—so that the heart is not empty. When these feelings or some one of them, directed toward God, are in it, then our prayer-words are prayer; when they are absent—they are not yet prayer.

(Letter 227. Issue 2, p. 33–34)