John Muir (1838-1914) was an influential naturalist, author, environmental philosopher, and advocate for the preservation of wilderness areas in the United States. In 1869, Muir travelled to California and spent a long time in the area that is now the Yosemite National Park. This narrative takes the form of a hiking guide filled with adventure. Muir was a master of description, providing stirring portraits of the area's wildlife, waterfalls, valleys, meadows, giant sequoias groves, lakes, mountains, and glaciers. About Yosemite Falls, he writes, "At the top of the fall they seem to burst forth in irregular spurts from some grand, throbbing mountain heart."