Case file · Sacred site
The descent into the oracle of Trophonius
Pausanias, who consulted it himself, describes how visitors to the oracle of Trophonius at Lebadea were lowered feet first into a narrow chasm and came back terrified and unable to laugh.
160 CE · 38.43, 22.87 · status: account
The account
After days of purification, drinking from the springs of Forgetfulness and Memory, the consultant crawled into an opening and was pulled through 'as by a whirlpool'. Afterwards priests set him on the Chair of Memory to report what he had seen or heard. Pausanias (9.39) says he writes from personal experience, which makes this a rare first-hand account of an ancient altered-state rite.
The sceptical view
Sensory deprivation, fasting, fear and suggestion are enough to explain the experiences; the site has not been firmly located.