The act of sleeping in a sanctuary, in order to obtain medical relief, either through revelations by dreams, or through a divine visitation, was termed _incubation_. According to the philosophy of oneiromancy, or the art of taking omens from dreams, during sleep the soul was released from the body, and thus enabled to soar into spiritual regions and commune with celestial beings. Therefore memories of ideas suggested in dreams were cherished as divine revelations.[101:1] The opinion has been advanced that the methods employed to procure "temple sleep" were similar to those in use at the present time for the production of the hypnotic state. A cure was effected by awakening a healing instinct in the patient's subconscious mind.[101:2] So far as we are aware, no authentic rational explanation has been given of the phenomenal appearance of a god in the patient's presence. It seems plausible that Asklepios, the Grecian Esculapius, was personated by some priest of majestic mien, who gave oracular medical advice, which serves as a powerful therapeutic suggestion. Various attendant circumstances doubtless contributed to impress the patient's highly wrought imagination, such as the dim light, the sense of mystery, and, it may be, certain tricks of ventriloquism. In the earliest days of temple-sleep, that is, probably about the seventh century B. C., this mode of treatment was practised without a tinge of superstition, the applicants' faith being deep and sincere. For in that era the belief was general that human art was powerless to cure disease, and the gods alone could furnish aid. Temple-sleep, wrote Dr. Hugo Magnus, was not degraded into superstition until the physicians had come to the conclusion that the phenomena of disease were not evidence of divine displeasure, but that they were due to natural causes. When therefore this new belief became established, temple-sleep degenerated into a superstitious rite. As early as the fifth century B. C., the celebrated poet, Aristophanes, in his comedy, "Plutus," severely criticized this ceremony, as practised in his time. And, although the more enlightened among the Greeks came to regard it with disfavor, the custom was never entirely abandoned by the ancient world.