Ralph Waldo Emerson was an American poet, essayist, and philosopher. He is best known for his works of poetry and essays, which were influential during the Transcendentalist movement of the mid-19th century. Emerson's most famous poem is 'The Concord Hymn, ' which celebrates the Battle of Concord. He is also remembered for his essays such as 'NATURE' and 'Self-Reliance.' Emerson was a major figure in the Transcendentalist movement, which sought to bring together spirituality and NATURE. He was also a mentor to many of the leading figures of the movement, including Henry David Thoreau and Walt Whitman.