There's a region here in Brazil which has very special mountains and caves. I know a man that lives there who's on his 80s now, is graduated in Austria as a psychologist and engineer and has also learned a lot from native shamans here. Once I asked him what he thought about Carlos Castañeda, to which he responded:

"If what he wrote was true, he was a great shaman. If it was a lie, he was a great shaman".