Ralph Waldo Emerson (May 25, 1803 – April 27, 1882) is an American essayist, lecturer, and poet, who leads the Transcendentalist movement of the mid-19th century.

He is seen as a champion of individualism and a prescient critic of the countervailing pressures of society, and he disseminates his thoughts through dozens of published essays and more than 1,500 public lectures across the United States.

Emerson gradually moves away from the religious and social beliefs of his contemporaries, formulating and expressing the philosophy of Transcendentalism in his 1836 essay, Nature.

Following this groundbreaking work, he gives a speech entitled The American Scholar in 1837, which Oliver Wendell Holmes, Sr. considers to be America's "Intellectual Declaration of Independence".

Emerson writes most of his important essays as lectures first, then revises them for print.

His first two collections of essays – Essays: First Series and Essays: Second Series, published respectively in 1841 and 1844 – represent the core of his thinking, and include such well-known essays as Self-Reliance, The Over-Soul, Circles, The Poet and Experience.

Together with Nature, these essays make the decade from the mid-1830s to the mid-1840s Emerson's most fertile period.

Emerson writes on a number of subjects, never espousing fixed philosophical tenets, but developing certain ideas such as individuality, freedom, the ability for humankind to realize almost anything, and the relationship between the soul and the surrounding world.

Emerson's "nature" was more philosophical than naturalistic: "Philosophically considered, the universe is composed of Nature and the Soul."

His work has greatly influenced the thinkers, writers and poets that have followed him.

When asked to sum up his work, he said his central doctrine was "the infinitude of the private man."

(Ward, Julius H. (1887).

The Andover Review.

Houghton Mifflin., p.

389.)

Emerson is also well known as a mentor and friend of fellow Transcendentalist Henry David Thoreau.