"The Spartans were sticklers for obedience to the law (nomos) as the guide to proper behavior on matters large and small. When the ephors entered office, for example, they issued an official proclamation to the men of Sparta: 'Shave your moustache and obey the laws.' The depth of Spartan respect for their system of government under law was symbolized by their tradition that Apollo of Delphi had sanctioned it with an oracle called the Rhetra. A Spartan leader named Lycurgus, they said, had instituted the reforms that the Rhetra institutionalized. Even in antiquity historians had no firm information about the dates of Lycurgus's leadership or precisely how he changed Spartan laws. All we can say today is that the Spartans evolved their law-based political system during the period from about 800 to 600 B.C. Unlike other Greeks, the Spartans never had their laws written down. Instead, they preserved their system from generation to generation with a distinctive, highly structured way of life based on a special economic foundation."

--Thomas R. Martin, An Overview of Classical Greek History from Mycenae to Alexander