Prayer initially consists of rational worship, whereas after purification and illumination it becomes noetic prayer: prayer from the heart, “ceaseless memory of God” (Met. Hierotheos, 2010, p. 185). Noetic prayer occurs according to the degree of liberation of the nous, the heart of the soul, from reason, through illumination. Rational worship or prayer is full of images and concepts, whereas noetic prayer is pure, free of both images and fantasies. Rational prayer results from our concentrating to pray, whereas noetic prayer is activated spontaneously by the Holy Spirit. Rational prayer is characteristic of purification, but before we have been purified, whereas noetic prayer is characteristic of illumination of the nous, the heart of the soul.
Met. Hierotheos. (2010). The illness and cure of the soul, 2nd ed. rev. Levadia, Greece: Birth of Theotokos Monastery.