NATIONAL BESTSELLER • The "poet laureate of medicine" (The New York Times) and author of The Man Who Mistook His Wife for a Hat weaves together stories of mind-altering experiences to reveal what they tell us about our brains, our folklore and culture, and why the potential for hallucination exists in us all.  "Sacks has turned hallucinations from something bizarre and frightening into something that seems part of what it means to be a person. His book, too, is a medical and human triumph.” —The Washington Post “An absorbing plunge into a mystery of the mind.” —Entertainment Weekly To many people, hallucinations imply madness, but in fact they are a common part of the human experience. These sensory distortions range from the shimmering zigzags of a visual migraine to powerful visions brought on by fever, injuries, drugs, sensory deprivation, exhaustion, or even grief. Hallucinations doubtless lie behind many mythological traditions, literary inventions, and religious epiphanies. Drawing on his own experiences, a wealth of clinical cases from among his patients, and famous historical examples ranging from Dostoevsky to Lewis Carroll, the legendary neurologist Oliver Sacks investigates the mystery of these sensory deceptions: what they say about the working of our brains, how they have influenced our folklore and culture, and why the potential for hallucination is present in all humans.