Huxley first took mescaline in 1953 and continued his experiments with hallucinogenic drugs until 1963 when - on his deathbed - he asked for and was given LSD. In these short but intensely illuminating essays, he explores the effects of the mescaline experience, describing how the drug enabled him to discover a 'sacramental vision of reality'. He also discusses the spiritual and moral implications of the experience, demonstrating how negative emotions can transform man's perceptual Nirvana into a 'schizophrenic hell'.