). A celebrated Sophist, born at Abdera, in
Thrace, probably about B.C. 480, and died about 411, at the age of nearly seventy years. It is
said that Protagoras was once a poor porter, and that the skill with which he had fastened
together, and poised upon his shoulders, a large bundle of wood, attracted the attention of
Democritus, who conceived a liking for him, took him under his care, and instructed him in
philosophy (Diog. Laert. ix. 53
; x. 8; Gell. v.
). This well-known story, however, appears to have arisen out of the statement of
Aristotle that Protagoras invented a sort of porter's knot for the more convenient carrying of
burdens. In addition to this, Protagoras was about twenty years older than Democritus.
Protagoras was the first who called himself a Sophist, and taught for pay; and he practised
his profession for the space of forty years. He must have come to Athens before B.C. 445,
since he drew up a code of laws for the Thurians, who left Athens for the first time in that
year. Whether he accompanied the colonists to Thurii, we are not informed; but at the time of
the plague (430 B.C.) we find him again in Athens. Between his first and second visit to
Athens he had spent some time in Sicily, where he had acquired great fame; and he brought with
him to Athens many admirers out of other Greek cities through which he had passed. His
instructions were so highly valued that he sometimes received 100 minae from a pupil; and
Plato says that Protagoras made more money than Phidias and ten other sculptors. In 411 he was
accused of impiety by Pythodorus, one of the Four Hundred. His impeachment was founded on his
book on the gods, which began with the statement, “Respecting the gods, I am unable
to know whether they exist or do not exist” (Diog. Laert. ix.
). The impeachment was followed by his banishment, or, as others affirm, only by the
burning of his book. His doctrine was, in fact, a sort of agnosticism based upon the
impossibility of attaining any absosolute criterion of truth. It is summed up in the sentence,
“Man is the measure of all things” (πάντων
, or, in Latin, homo mensura omnium
implying that each one must be his own final authority; for just as each thing appears to any
individual, so it really is for him. This doctrine is therefore styled Individualism.
Protagoras wrote a large number of works, of which the most important were entitled
) and On the
). The first contained the theory
refuted by Plato in the Theaetetus.
Plato gives a vivid picture of the
teaching of Protagoras in the dialogue that bears his name. Protagoras was especially
celebrated for his skill in the rhetorical art. By way of practice in the art he was
accustomed to make his pupils discuss theses (communes loci
), an exercise
which is also recommended by Cicero. He also directed his attention to language, and
endeavoured to explain difficult passages in the poets. He is said to have been the first to
make the grammatical distinctions of moods in verbs and of genders in nouns.
See Geist, De Protagora Sophista (Giessen, 1827)
Protagoras Leben und Sophistik (Hamburg, 1832)
De Protagorae Vita (Groningen, 1853)
; Blass, Attische
, pp. 23-29; Ueberweg, Hist. of Philosophy
, i. pp. 73-76
(Eng. trans. N. Y. 1872)