...In the divine vision of prayer there exist measures and distinction of gifts. Till this point it is still prayer, for the mind has not yet passed to where there is no prayer: that state is above prayer. The movements of the tongue and the heart in prayer are keys; what comes after them, however, is the entrance into secret chambers. Here let every mouth, every tongue become silent, and let the heart (the treasury of the thoughts), and the intellect (the ruler of the senses), and the mind (that swift-winged and most shameless bird), and their every device be still. Here let those who seek tarry, for the Master of the house has come.
-- from Homily 23 of the Ascetical Homilies of St. Isaac the Syrian