Plato believed in an eternal existence of the idea of justice and sat down to talk about it all the concepts of natural law. Archytas of Tarentum (Pythagorean disciple) made a distinction between written law and unwritten laws. The last, he said, were dictated by the gods and that among other things served as basis for written laws. The violation of the unwritten laws entailed sanctions represented divine punishment, personal misfortunes, calamities and even family members could be the cause of death. The unwritten laws, so, are transcendent to the written rules and has its source in something greater than human beings, the divine.
Sophocles (493-406 BC) which was considered by many historians as the greatest tragic poets, in his entirely his idea ANTIGONE plasma on natural law: King Creon forbids the burial of Polynices. Antigone, sister of Polynices, disobeys his king and buries her brother, alleging that he had higher laws, emanating from the gods, who ordered to bury the dead, why was entirely lawful to disobey a rule emanating from a being human as the King to fulfill a divine mandate. On the other hand the bulk of the Sophist SCHOOL is the first to post a very specific theory on natural law. Distinguish what is right by nature or specified by the nature (physis) and just as human laws in force (Nomoi DIKAIOI) or manmade. The latter do not always correspond with the first as such despite the fact that the physis of the men was about the same animal, the prefectures established differences between them to make some free and others slaves, some citizens and other foreigners etc.