πάντων χρηµάτων µέτρον ἐστίν ἄνθρωπος, τῶν µέν ὄντων ὡς ἐστιν, τῶν δέ οὐκ ὄντων ὡς οὐκ ἔστιν → man is the measure of all things, of things which are, that they are, and of things which are not, that they are not (Protagoras fr.1)
