Hallucinations don't belong wholly to the insane. They are commonly linked to sensory deprivation, intoxication, illness, or injury. For thousands of years, humans have used hallucinogenics to achieve them. Here, with elegance, curiosity, and compassion, Oliver Sacks weaves together stories of his patients and of his own mind-altering experiences to illuminate what hallucinations tell us about our brains, our culture, and ourselves. (Bestseller).