This quotation is restated in Plato's Theaetetus at 152a. Sextus Empiricus gives a direct quotation in Adv. math. 7.60: πάντων χρημάτων μέτρον ἐστὶν ἄνθρωπος, τῶν μὲν ὄντων ὡς ἔστιν, τῶν δὲ οὐκ ὄντων ὡς οὐκ ἔστιν. Man is the traditional translation for the Greek word anthrōpos (human being, person), representing a general statement about human beings.
Poster, Carol (2005) [2002]. "Protagoras". Internet Encyclopedia of Philosophy. Retrieved 22 October 2013.
The Internet Encyclopedia of Philosophy - Protagoras (c. 490 BCE – c. 420 BCE), Accessed: October 6, 2008. "While the pious might wish to look to the gods to provide absolute moral guidance in the relativistic universe of the Sophistic Enlightenment, that certainty also was cast into doubt by philosophic and sophistic thinkers, who pointed out the absurdity and immorality of the conventional epic accounts of the gods. Protagoras' prose treatise about the gods began "Concerning the gods, I have no means of knowing whether they exist or not or of what sort they may be. Many things prevent knowledge including the obscurity of the subject and the brevity of human life".
