I'm a big fan of Steve Beyer's "Singing to the Plants: A Guide to Mestizo Shamanism in the Upper Amazon". He seems well grounded and rational, and is at the same time sufficiently experienced with the plants to be able to talk fluently about the strange phenomena associated with shamanry without dismissing such phenomena outright (as do many rationalists) or "going off the deep end" and specifying an ontological status for the "spirits", as do many "New Age" people. Here's a new article of his posted in "The Journal of Shamanic Practice". En-joy!

"What Do the Spirits Want From Us?"

"Shamans in the Upper Amazon have established a relationship of trust and love with the healing and protective spirits of the plants. To win their love, to learn to sing to them in their own language, shamans must first show that they are strong and faithful, worthy of trust. To do this, they must go into the wilderness, away from other people, and follow la dieta, the restricted diet - no salt, no sugar, no sex - and ingest the sacred plant that is the body of the spirit...

The spirits are all here, with us, right now.

This world is as magical - as filled with ogres and allies, signs and mysteries - as the miraculous world of the vision fast."

Agreed - his chapter on performance was worth the price of admission into that book. I was not not expecting it to be as good as it was.