To add to this, Michael Pollan (author of Omnivore's Dillema and a Berkeley/Harvard prof) recently published a lucid account of the history of psychedelics and 'psychotomimetics' (as they were originally named, owing to their perceived ability to mimic psychosic) with the title 'How to change your mind' [1].

In the book, Pollan details the recent renaissance in clinical psychedelic research to treat depression and help terminally-ill patients. The hope is that the 'noetic quality' of psychedelic trips--a term coined by William James in the context of religious experiences--can help pierce through the defences of one's ego. This 'noetic quality' refers to the perception that a psychedelic trip feels like 'total reality'; a series of 'revealed truths' rather than drug-induced illusions. This bears resemblance to revelatory experiences in religious contexts and the two are intimately tied in many Shamanic practices.

By inducing a long-lasting feeling of transcendence, researchers hope that psilocybin et al. can act as a more direct way to short-circuit destructive patterns of thought and help one come to terms with death (as opposed to, or in conjunction with, traditional therapy).

Pollan writes that in controlled settings with a trained guide, 'bad trips' are quite rare, though they can occur.

[1] https://www.goodreads.com/book/show/36613747-how-to-change-y....