Ralph Waldo Emerson (May 25, 1803 – April 27, 1882), who went by his middle name Waldo, was an American essayist, lecturer, philosopher, minister, abolitionist, and poet who led the Transcendentalist movement of the mid-19th century. He was seen as a champion of individualism and critical thinking, as well as a prescient critic of the countervailing pressures of society and conformity. Friedrich Nietzsche thought he was "the most gifted of the Americans," and Walt Whitman called Emerson his "master".
Emerson gradually moved away from the religious and social beliefs of his contemporaries, formulating and expressing the philosophy of Transcendentalism in his 1836 essay, Nature. His speech "The American Scholar," given in 1837, was called America's "intellectual Declaration of Independence" by Oliver Wendell Holmes Sr.
Emerson wrote most of his important essays as lectures and then revised them for print. His first two collections of essays, Essays: First Series (1841) and Essays: Second Series (1844), represent the core of his thinking.