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 Heraclitean flux in Nature was extended to Mind also; only the sensation exists, and that only at the moment of its occurrence; this alone is truth, this alone is reality; all else is delusion. [180]