An unwearying wanderer, a keen observer, a sensitive and passionate writer. That was John Muir, who went forth year after year into the wilderness to study wildlife, climate, geology. In this perceptive, absorbing biography author Robert Silverberg reveals why Americans today revere Muir's memory as a great leader in the struggle against man's ruination of his own environment. Though Muir was born more than a century and a half ago, Silverberg portrays a man as modern in outlook as today's youth.