is at that time authoritative, though it owes its existence to art and the laws, and not in any way to nature. All these, my friends, are views which young people imbibe from men of science, both prose-writers and poets, who maintain that the height of justice is to succeed by force; whence it comes that the young people are afflicted with a plague of impiety, as though the gods were not such as the law commands us to conceive them; and, because of this, factions also arise, when these teachers attract them towards the life that is right “according to nature,” which consists in being master over the rest in reality, instead of being a slave to others according to legal convention.This antithesis between “Nature” (φύσις) and “Convention” (νόμος) was a familiar one in ethical and political discussion from the time of the Sophists. The supremacy of “Nature,” as an ethical principle, was maintained (it is said) by Hippias and Prodicus; that of “Convention,” by Protagoras and Gorgias: Plato goes behind both to the higher principle of Reason (νοῦς), cp. Introduction. p. xiv.