For centuries, hallucinogens have been of great significance in the ideology and religious practices of primitive societies. In fact, the use of psychotropic plants to achieve states of religious ecstasy goes back almost to the beginning of human culture. Furthermore, the content of the psychedelic experience in the West today has been found to be similar to that of the religious pilgrimages of Oriental and aboriginal New World groups. But one fundamental difference overshadows all similarities: In the traditional cultures described in this collection of ten essays, the hallucinogenic "trip" is a means to an end--a quest for confirmation of traditional values, for unity with the tribal ancestors. In contemporary Western society, by contrast, it tends to be an end in itself and a rejection of the society's values--perhaps, it has been suggested, because Western drug-users tend to be a-cultural. Clearly, we have much to learn from an objective study of societies with long histories of sanctioned, and controlled, drug use to achieve recognized cultural objectives.