To Colin Fletcher, accustomed to solitary strolling (he had walked the Coast alone), the Grand Canyon was ""mysterious and terrible--and beckoning."" It summoned him to a two-month sojourn alone. Setting out in April, with air drops planned for supplies, he descended into this ""huge natural museum of the earth's history."" He faced physical and psychic challenges as he explored from the Rim to the floor of the Canyon, from 200 million to one-and-a-half billion years in time. His record is as much that of the effect of solitude and splendor as it is of the ""stubborn and inescapable paradox of simple living."" He draws the reader into the tempo and tenor of his experience as he encounters beaver, rattlesnakes, the Colorado, investigates Hopi Sipapus and ancient settlement remains. In full dress--hat, socks, and shoes--he sensed himself as part of nature, man as an evolving outgrowth of all that preceded him. The author makes a plea for the preservation of the Canyon as it is. His book is a convincing exhibit A in presenting his case.