Protagoras was a pre-Socratic Greek philosopher and rhetorical theorist. He is numbered as one of the sophists by Plato. In his dialogue Protagoras, Plato credits him with inventing the role of the professional sophist. 490 BC – 420 BC; died at about 70. Alive at the same time as The Buddha, Sophocles, Hippocrates, Thucydides, and Confucius. Wiki link