Henry David Thoreau (July 12, 1817 – May 6, 1862) was an American essayist, poet, philosopher, abolitionist, naturalist, tax resister, development critic, surveyor, and historian. A leading transcendentalist, Thoreau is best known for his book Walden, a reflection upon simple living in natural surroundings, and his essay "Civil Disobedience", an argument for disobedience to an unjust state.

First published in 1854, Walden details Thoreau's experiences over the course of two years, two months, and two days in a cabin he built near Walden Pond, amidst woodland owned by his friend and mentor Ralph Waldo Emerson, near Concord, Massachusetts. Thoreau used this time to write his first book, A Week on the Concord and Merrimack Rivers. The experience later inspired Walden, in which Thoreau compresses the time into a single calendar year and uses passages of four seasons to symbolize human development.

By immersing himself in nature, Thoreau hoped to gain a more objective understanding of society through personal introspection. Simple living and self-sufficiency were Thoreau's other goals, and the whole project was inspired by transcendentalist philosophy, a central theme of the American Romantic Period.

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