1911 Encyclopædia Britannica/Protagoras
PROTAGORAS (c. 481–411 B.C.), Greek philosopher, was born at Abdera. He is known as the first of the Sophists (q.v.), i.e. he was the first to teach for payment. It is said that he received nearly £400 from a single pupil. He learned philosophy in the Ionian school, and was perhaps a pupil of Democritus, though this is doubtful on chronological grounds. He was an older contemporary of Socrates. He was so highly esteemed by Pericles that he was entrusted with the task of framing laws for the new colony of Thurii (Plut. Pericles, 36). At the age of seventy, having been accused by Pythodorus, and convicted of atheism, Protagoras fled from Athens, and on his way to Sicily was lost at sea. According to Plato (Prot., 318 E), he endeavoured to communicate “prudence” (εὐβουλία) to his pupils, “which should fit them to manage their households, and to take part by word and deed in civic affairs.” The education which he provided consisted of rhetoric, grammar, style and the interpretation of the poets. His formal lectures were supplemented by discussions amongst his pupils. He left behind him several treatises, of which only a few fragments have survived. In Truth, by way of justifying his rejection of philosophy or science, he maintained that “man is the measure of all things—of what is, that it is, and of what is not, that it is not.” Besides Truth, and the book Of the Gods which caused his condemnation at Athens, Diogenes Laërtius attributes to him treatises on political, ethical, educational and rhetorical subjects. Protagoras was the first to systematize grammar, distinguishing the parts of speech, the tenses and the moods.
Authorities. Diog. Laërt., ix. 8, &c.; the very different representations in Plato’s Protagoras and Theaetetus; the fragments in Johannes Frei, Quaestiones Protagoreae (Bonn, 1845), and A. J. Vitringa, Disquisitio de Protagorae vita et Philosophia (Gröningen, 1852); for the Thurian legislation, M. H. E. Meier, Opuscula, i. 222, and Gomperz in Franz Hoffmann’s Beiträge zur Gesch. des griech. und röm. Rechts (1870). On Protagoras’ philosophy see the histories of philosophy, e.g. Gomperz, Greek Thinkers (Eng. trans., 1901) i. 438–475 and 586–592, Zeller, Ueberweg, Erdmann, and works quoted under Sophists.