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, nonetheless 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.