The fifth century is the century of nomos, a concept difficult to translate, as it covers several different semantic fields. Usually nomos is rendered as ‘law’, but this is a reductive translation, since the term describes not just positive laws but also traditions, customs, and established practices. Besides, as Aristotle was to observe, the two meanings ‘law’ and ‘tradition’ are closely related: ‘For the law has no power to command obedience except that of habit, which can only be given by time’ (Politics, 1269a20). In short, nomos is anything which is assigned some value, any norm accepted by a group. From the late sixth century onwards, this term acquired a central place in the Greek world, becoming a privileged object of reflection for the sophists. The most significant element is its spread as a technical term for written law, particularly in Athenian democracy. Prior to this, it chiefly referred to customs and traditions. Yet its growing importance is not devoid of problematic aspects. The greater economic and political stability attained through the victorious wars against the Persians led to an increase in travel, cultural exchanges, and trade, which contributed to broadening the perspectives and knowledge of the Greeks. One of the most striking observations they made concerned the wide range of laws and traditions in force in the various cities and states: nomos is indeed a crucial value, as the law and tradition governing the life of a community; but it is in any case relative, as it varies from city to city. The acknowledgement of the relativity of nomos is a central theme in fifth-century literature, as may be inferred from some famous passages by Pindar, Herodotus, and Aeschylus. At first sight, the conclusions reached by these authors would appear to emphasize the capacity of nomos to impose itself: as a verse by Pindar states, nomos ‘is the king of all things’ (fr. 169a Snell-Mähler). Yet the ascertainment of the range of laws and traditions in existence could also lead to moral relativism and to the conclusion that there are no absolute, universal or objective values (Dissoi logoi, 90, 2.18 D.-K. = 40, 2.18 L.-M.).