Henry David Thoreau (1817-62) was an essayist, poet, and philosopher as well as one of America's foremost nature writers. He lived most of his life in Concord, Massachusetts, and was a close friend and protégé of Transcendentalist philosopher Ralph Waldo Emerson. Walden, a meditation on life in the woods, and Civil Disobedience, a polemic advocating dissent from unjust government, are his best-known works.