29. Devils often transform themselves into angels of light and take the form of martyrs, and make it appear to us during sleep that we are in communication with them. Then, when we wake up, they plunge us into unholy joy and conceit. But you can detect their deceit by this very fact. For angels reveal torments, judgments
This is the third step, which is equal in number to the Trinity. He who has reached it, let him not look to the right hand nor to the left.