tless what
Protagoras {86} intended to indicate as the purpose of his teaching,
when he called himself a Sophist. But the ability he really undertook
to cultivate was ability to _persuade_, for Greece at this time was
nothing if not political; and persuasive oratory was the one road to
political success. And as Athens was the great centre of Greek
politics, as well as of Greek intellect, to Athens Protagoras came as a
teacher.

He was born at Abdera, in Thrace (birthplace also of Democritus), in
480 B.C., began to teach at Athens about 451 B.C., and soon acquired
great influence with Pericles, the distinguished leader of the Athenian
democracy at this time. It is even alleged that when in 445 the
Athenians were preparing to establish a colony at Thurii in Italy,
Protagoras was requested to draw up a code of laws for the new state,
and personally to superintend its execution.

After spending some time in Italy he returned to Athens, and taught
there with great success for a number of years. Afterwards he taught
for some time in Sicily, and died at the age of seventy, after [178]
about forty years of professional activity. He does not seem to have
contented himself with the merely practical task of teaching rhetoric,
but in a work which he, perhaps ironically, entitled _Truth_, he
enunciated the principles on which he based his teaching. Those
principles were summed up in the sentence, "Man (by which he meant
_each_ man) is {87} the measure of all things, whether of their
existence when they do exist, or of their non-existence when [179] they
do not." In the development of this doctrine Protagoras starts from a
somewhat similar analysis of things to that of Heraclitus and others.
Everything is in continual flux, and the apparently real objects in
nature are the mere temporary and illusory result of the in themselves
invisible movements and minglings of the elements of which they are
composed; and not only is it a delusion to attempt to give a factitious
reality to the things which appear, it is equally a delusion to attempt
to separate the (supposed) thing perceived from the perception itself.
A thing is only as and when it is perceived. And a third delusion is
to attempt to separate a supposed perceiving mind from the perception;
all three exist only in and through the momentary perception; the
supposed reality behind this, whether external in the object or
internal in the mind, is a mere imagination. Thus the