Epicurus was an ancient Greek philosopher who founded Epicureanism, a school of thought promoting a happy, tranquil life through ataraxia (peace) and aponia (absence of pain). He emphasized the importance of friendship, self-sufficiency, and the rejection of fear, particularly fear of death. While most of his works are lost, his surviving ideas, including the atomic "swerve" supporting free will, greatly influenced later thinkers during the Enlightenment and beyond.