The essential characteristic of any city, of any polis, is the founding act. This act, played once and for all, embodies a higher, invisible reality, that which allowed the Polis to exist. As such, the laws which the Polis gives herself reflect this reality, and are thus immutable. Thus Solon becomes the lawgiver of Athens, and his laws embody the essence of Athen’s exsitence; likewise of Lacedaemon and Rome; and so too Moses becomes the lawgiver of the people of God: the Ten Commandements are immutable, because they embody the eternal, pre-existing law of God.