History is littered with evidence of humanity's fascination with drugs and the pursuit of altered states. From early Romanticism to late-nineteenth-century occultism and from fin de siècle Paris to contemporary psychedelic shamanism, psychoactive substances have playedcatalyzing people. Yet serious analysis of the religious dimensions of modern drug use is still lacking. the use of drugs and the pursuit of transcendence from the nineteenth century to the present day. Beginning with the Romantic fascination with opium, it chronicles the discovery of anesthetics, the psychiatric and religious interest in hashish, the bewitching power of mescaline and hallucinogenic fungi, the more recent uses of LSD, as well as the debates surrounding drugs and religious experience. This fascinating and wide-ranging sociological and cultural history fills a major gap in the study of religion in the modern world and our understanding of the importance of countercultural thought, offering new and timely insights into the controversial relationship between drugs and mystical experience.