Ralph Waldo Emerson is best known for his theory of individualism and self-reliance, which he expounded upon in his essays, poems, and lectures. At its core, this theory holds that people should trust their own instincts and ideas, rather than blindly following the opinions and beliefs of others. According to Emerson, the inner voice is the key to true happiness and fulfillment, and it should be the guiding force in people's lives. His theory of individualism and self-reliance continues to be widely studied and celebrated today, and it remains one of his most enduring contributions to American literary and cultural history.