Elaborate legal enactments codified in Babylonia by the 10th century B.C. find striking parallels in Hebrew, late Jewish (Talmudic), Syrian and Mahommedan law, or in the unwritten usages of all ages; for even where there were neither written laws nor duly instituted lawgivers, there was no lawlessness, since custom and belief were, and still are, almost inflexible.
Legal rights are everywhere taking the place of unwritten customs. Land, which was before merely a source of livelihood to the cultivator and of revenue to the state, has now become the subject of commercial speculation.
When Aristotle at the age of eighteen came to Athens, Plato, at the age of sixty-two, had probably written all his dialogues except the Laws; and in the course of the remaining twenty years of his life and teaching, he expounded " the socalled unwritten dogmas " in his lectures on the Good.
In the unwritten lectures of his old age, he developed this formal into a mathematical metaphysics.