"It can not be an accident that our evolution has given us this potential, evolution gives us nothing, unless it is useful, and it therefore suggests that these altered states of consciousness are incredibly useful to the human species."

Graham Hancock

"Another interesting thing about ayahuasca is that there is nothing in it that doesn’t occur within the ordinary human brain, there’s just more of the ordinary brain chemistry there. So that implies that these extraordinary states of mind, group mindedness, three-dimensional hallucinations, and so forth are never the less not that far removed from ordinary states of brain chemistry."

Terrance McKenna