This collection of essays are mainly casebook studies. Neurological patients, Oliver Sacks once wrote, are travellers to unimaginable lands. This book offers portraits of seven such travellers, including a surgeon consumed by the compulsive tics of Tourette's syndrome unless he is operating, an artist who loses all sense of colour in a car accident, but finds a new sensibility and creative power in black and white, and an autistic professor who cannot decipher the simplest social exchange between humans, but has built a career out of her intuitive understanding of animal behaviour. These are paradoxical tales, for neurological disease can conduct one or other modes of being which - however abnormal they may be to our way of thinking - may develop beauties and virtues of their own. Thus one young man, Stephen Wiltshire, who is both retarded and autistic, none-the-less has produced thousands of astonishing drawings. The exploration of these individual lives is not one that can be conducted in a consulting room or office, and Sacks has taken off his white coat and deserted the hospital, by and large, to join his subjects in their own environments. Sacks also offers a perspective on the way our brains construct our individual worlds, and reconstructs the mental acts that are largely taken for granted - the act of seeing, the transport of memory and the notice of colour.