Protagoras of Abdera was one of the most celebrated of the early Greek Sophists and a key figure in the history of philosophy. He is credited with creating the role of the professional Sophist, teaching virtue and practical skills for a fee. Central to his philosophy is the famous doctrine that "Man is the measure of all things," which posits a radical form of relativism. His teachings and writings, though largely lost, profoundly influenced his contemporaries, including Plato, who named a dialogue after him.