The Spirit of Shamanism is a psychiatrist's look at the essence of shamanic practices. Robert Walsh covers such topics as the shaman's initiation, accessing the spirit world, healing, psychedelic drugs, and New Age adaptations. Although Walsh looks across the broad range of the shamanic experience, the most interesting sections of the book deal with the topic of his expertise: mental illness and psychological health. He explores such questions as 1) whether shamanic initiation and trance states are psychotic or schizophrenic; 2) the difference between trance states and mental illness; and 3) the effects of music, trickery and the placebo effect on healing.
On the negative side, Walsh has a poor opinion of anthropologists, yet he relies heavily on the work of anthropologists who are marginal in the anthropological community. Many of his resources are outdated. The book is not very deep, yet this makes it accessible to just about anyone. It doesn't "feel" like it's written by an M.D./Ph.D. -- Walsh slips easily into New Age thinking -- yet, again, it's accessible.
This quasi-scientific book is good for anyone interested in knowing more about the psychology of shamanism. It's well-written, the chapters are short, and it's easy to understand.