" A theophany consists of a self-disclosure by the divine. It does not consist of something the percipient does; it consists of something the divine—the God or gods, the high power—does. Moses did not create the burning bush. Elijah, on Mount Horeb, did not generate the low, murmuring voice. How are we to distinguish a genuine theophany from a mere hallucination on the part of the percipient? If the voice tells him something he does not know and could not know, then perhaps we are dealing with the genuine thing and not the spurious. "

― Philip K. Dick , The VALIS Trilogy