Many would call John Muir one of our earliest environmentalists. Achievements associated with this Scottish-born naturalist include the elucidation of the natural history and glacial history of the Sierra Nevada range and the establishment of Yosemite National Park and the Sierra Club, along with his advocacy of nature via his written and spoken work. There are several biographies of Muir that cover all aspects of his life and career as an environmentalist. Two important titles are Son of the Wilderness: The Life of John Muir, by Linne Marsh Wolfe, and A Passion for Nature: The Life of John Muir, by Donald Worster. Wolfe’s book, originally published in 1945, won a Pulitzer Prize and is now available in an updated paperback edition. Worster’s scholarly work is very well documented, with some thirty pages of notes, and is a very comprehensive account of Muir’s contributions.