All PRAYER, READING AND MEDITATION are aimed at purity of heart -

 an unconditional and totally humble surrender to God, a total acceptance of ourselves and of our situation as willed by him.  It means the renunciation of all deluded images of ourselves, all exaggerated estimates of our own capacities, in order to obey the will of God as it comes to us in the difficult demands of life in its exacting truth.  Purity of heart is then correlative to a new spiritual identity - the "self" as recognized in the context of realities willed by God - Purity of heart is the enlightened awareness of the new man, as supposed to the complex and perhaps rather disreputable fantasies of the "old man."

     Meditation is then ordered to this new insight, this direct knowledge of the self in its higher aspect. (CTP 68)