Originally 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.

Walden is a reflection upon simple living in natural surroundings. The work is part personal declaration of independence, social experiment, voyage of spiritual discovery, satire, and (to some degree) manual for self-reliance.

On The Duty of Civil Disobedience [formerly known as Resistance to Civil Government (Civil Disobedience)] was first published in 1849. In it, Thoreau argues that individuals should not permit governments to overrule or atrophy their consciences, and that they have a duty to avoid allowing such acquiescence to enable the government to make them the agents of injustice. Thoreau was motivated in part by his disgust with slavery and the Mexican-American War (1846-1848).

-Wikipedia

While living in solitude in a cabin on Walden Pond in Concord, Massachusetts, Henry David Thoreau wrote his most famous work, Walden, a paean to the idea that it is foolish to spend a lifetime seeking material wealth. In his words, "I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived."Thoreau's love of nature and his advocacy of a simple life have had a large influence on modern conservation and environmentalist movements.
-Library of Congress