Henry David ThoreauΒ (July 12, 1817Β β May 6, 1862) was an AmericanΒ essayist,Β poet, andΒ philosopher. Among his lasting contributions are hisΒ writings on natural historyΒ and philosophy, in which he anticipated the methods and findings ofΒ ecologyΒ andΒ environmental history, two sources of modern-dayΒ environmentalism.