In the nineteenth century, John Muir is the foremost spokesman of the protection of the American wilderness. He is recognized as the founder of the American environmental movement. Also, he is a prolific nature writer who publishes plenty of influential books for America. This article explores Muir's nature texts. It offers an investigation of Muir's ”wilderness ethic.” This paper examines how Muir resists the prevailing values of Christian religion and the industrial capitalism in the late nineteenth century, how he questions the ideology of anthropocentrism, how he expresses the principle of biocentric egalitarianism and the idea of interdependence, and how he presents the essential oneness of all living things. Through these observations, the paper shows that Muir's ”wilderness ethic”-founded upon a complete identification with nature and a deep respect for the rights of nature-makes him become a genuine ”deep ecologist.”