I just finished Breaking Open the Head by Daniel Pinchbeck, and I can honestly say it is one of the most fascinating books I have ever read. It is at once a history of the psychedelic movement, an exploration of shamanism, and an autobiographical spiritual narrative recounting the author's own mind-boggling experiences. I found myself underlining entire chunks of the book, as there were so many rich ideas which were either brand new to me or else entirely affirming of my own suspicions and views. I think I will leave it there, as it's far too brilliant and complex a book to sum up in just a few words, and I am frankly still digesting it. I will say that I did discover two of Pinchbeck's other projects, Reality Sandwich and Evolver, and have been delightedly poking around those two sites recently. Have a look.