This fascinating book discusses the role played by psychoactive mushrooms in the religious rituals of ancient Greece, Eurasia, and Mesoamerica. R. Gordon Wasson, an internationally known ethnomycologist who was one of the first to investigate how these mushrooms were venerated and employed by different native peoples, here joins with three other scholars to discuss the evidence for his discoveries about these fungi, which he has called entheogens, or "god generated within.