Man is the measure of all things. The first and greatest of the Sophists turned philosophy toward human judgment.
Protagoras was the most famous of the Sophists, traveling from city to city teaching rhetoric, argument, and civic virtue for a fee. His claim that 'man is the measure of all things' made truth relative to the perceiver. He wrote a book on the gods that began 'About the gods I cannot know either that they exist or that they do not.' Athens burned his books and banished him. Plato named a dialogue after him and treated him with surprising respect.
“Man is the measure of all things: of things that are, that they are, and of things that are not, that they are not.”
Became the most sought-after teacher in Athens, charging high fees for instruction in rhetoric and civic virtue. He was a friend of Pericles.
His book On the Gods was burned in the Athenian agora. He was banished from the city. He reportedly drowned at sea while fleeing.