Oliver Sacks has always been fascinated by islands - their remoteness, their mystery, above all the unique forms of life they harbor. For him, islands conjure up equally the romance of Melville and Stevenson, the adventure of Magellan and Cook, and the scientific wonder of Darwin and Wallace.

Drawn to the tiny Pacific atoll of Pingelap by intriguing reports of an isolated community of islanders born totally colorblind, Sacks finds himself setting up a clinic in a one-room island dispensary, where he listens to these achromatopic islanders describe their colorless world in rich terms of pattern and tone, luminance and shadow.

And on Guam, where he goes to investigate the puzzling neurodegenerative paralysis endemic there for a century, he becomes, for a brief time, an island neurologist, making house calls with his colleague John Steele, amid crowing cockerels, cycad jungles, and the remains of a colonial culture.

The islands reawaken Sacks' lifelong passion for botany - in particular, for the primitive cycad trees, whose existence dates back to the Paleozoic - and the cycads are the starting point for an intensely personal reflection on the meaning of islands, the dissemination of species, the genesis of disease, and the nature of deep geologic time.

Out of an unexpected journey, Sacks has woven an unforgettable narrative which immerses us in the romance of island life, and shares his own compelling vision of the complexities of being human.