Henry David Thoreau (1817–1862) was born in Concord, Massachusetts. He was a pioneer in civil disobedience, one of the most powerful forms of nonviolent protest against social injustice in the modern age. He was a lifelong abolitionist, and his philosophy of civil disobedience influenced the political thoughts and actions of such figures as Leo Tolstoy, Mahatma Gandhi, and Martin Luther King, Jr. He is best known for his book Walden, a treatise on self-reliance and spiritual discovery based on the two years he spent living alone in a cabin in the woods.