Anthropologist Jeremy Narby is the author of the quite extraordinary, ground-breaking book THE COSMIC SERPENT (1995). In this he describes the remarkable wisdom of the native tribes of the Upper Amazon, which includes a vast pharmaceutical knowledge of over 50,000 plants. Asked where this knowledge had come from, they said the spirits of the plants themselves gave this information to the shamans. Confused, and not believing what he had heard, Narby lived with these native peoples for some while, and eventually consented to take part in a shamanic initiation in which he ingested the hallucinogenic brew ayahuasca, which was said to aid communication with the spirit world.