Shamanism is one of the earliest and farthest-reaching magical and religious traditions, vestiges of which still underlie the major religious faiths of the modern world. The function of the shaman is to show his or her people the unseen powers behind the mere appearances of nature, as experienced through intuition, in trance states, or during ecstatic mystical visions. Shamans possess healing powers, communicate with the dead and the world beyond, and influence the weather and movements of hunting animals. The psychological exaltation of shamanism trance states is similar to the ecstasies of...