John Burroughs (April 3, 1837 - March 29, 1921) was an American naturalist, proponent of the American conservation movement and one of the most important practitioners of the American literary genre, the nature essay. He is best known for his observations on birds, flowers and rural scenes, but his essay topics also range to religion, philosophy, and literature. His achievements as a writer were confirmed by his election as a member of the American Academy of Arts and Letters. He enjoyed good physical and mental health during his later years until only a few months before his death when he began to experience lapses in memory and show general signs of advanced age including declining heart function. He died in 1921 at the age of 83. John Muir (April 21, 1838 - December 24, 1914) was a Scottish-born American naturalist, author, and early advocate of preservation of wilderness in the USA. His letters, essays, and books telling of his adventures in nature have been read by millions. His activism helped to save the Yosemite Valley, Sequoia National Park and other wilderness areas. The Sierra Club, which he founded, is now one of the most important conservation organizations in the USA. He died of pneumonia in 1914 at age 76.