 (2) Natural Justice: Callicles’ denunciation of conventional justice is bound up with a ringing endorsement of its opposite, the just ‘according to nature’; in fact his opening speech is perhaps our most important text for the sophistic contrast between nature [phusis] and convention [nomos]. Nomos is, as noted above (in section 1), first and foremost Law in all its grandeur, attributed by Hesiod to the will of Zeus. But in sophistic contexts, nomos is often used to designate some norm or institution—language, religion, moral values, law itself—as merely a matter of social construction. That is why nomos varies from polis to polis and nation to nation, and can be changed by our decisions. What is by nature, by contrast, is a kind of ethical and political ‘given’, outrunning our wishes or beliefs; and the contrast involves at least an implicit privileging of nature as inherently authoritative (see Kerferd 1981a, Chapter 10). This project of disentangling the contributions of nature and convention in human life can be seen as an extension to the human realm of Presocratic natural science, with its attempts to identify the eternal explanatory first principles [archai] behind the ever-changing, diverse phenomena of the cosmos.