“Until man has received the Comforter, he requires the Divine Scriptures to imprint the memory of good in his heart, to keep his striving for good constantly renewed by continual reading, and to preserve his soul from the subtleties of the ways of sin; for he has not yet acquired the power of the Spirit that drives away that delusion which takes soul-profiting recollections captive and makes a man cold through the distraction of his intellect. When the power of the Spirit has penetrated the [noetic] powers of the active soul, then in place of the law of the Scriptures, the commandments of the Spirit take root in his heart, and a man is secretly taught by the Spirit and needs no help from sensory matter. For, so long as it is from matter that the heart has its teaching, error and forgetfulness straightway follow the lesson; but when teaching comes from the Spirit, its memory is kept inviolate.”

St Isaac of Syria, The Ascetical Homilies, 6