The Amphiareion at Oropus, Greece, was one of the most important of the incubation centres in the ancient world. Here sleep-oracles were practised, alonside the art of snake-healing. Incubation was practised by elite priest intiates, who induced a sort of trance state in their patients:healingwas done on the detached spiritual body (now called the etheric body), which was viewed as containing the roots of all moral dispositions tht resulted in ill-health or disease, in the lower physical body.