The present article aims to analyze the meaning of the first occurrences of the expressions νόμος γεγραμμένος and νόμος ἄγραφος in order to demonstrate that both, as they appear, have a specific technical value and a political meaning. On the one hand, the analysis of the famous praise of the written law as guarantor of democratic equality in Euripidesʼ suppliant Women demonstrates that the expression νόμος γεγραμμένος is not simply limited to the writing of the law (which in itself does not guarantee de- mocracy), but indicates the law written and made public immediately, that is common property, and therefore able to ensure equal treatment of the people who appear before it. On the contrary, the ἄγραφος νόμος, far from expressing —as it will occur at a later time— the “custom”, the “divine law” or the “law of nature”, is principally the law that the γένη pretend to be source of law and integral part of the civic order. The conflict, often without solution, between the two orders of νόμοι is illustrated very well in several works in the change of the last decades of the Vth and the beginning of the IVth centuries B.C.: for instance in Sophoclesʼ antigone, as well as Andocidesʼ On the Mysteries and its probable reply, the pseudo-Lysian speech against andocides.