Aristotle. Universal law is the law of Nature.

Universal law is the law of Nature. For there really is, as every one to some extent divines, a natural justice and injustice that is binding on all men, even on those who have no association or covenant with each other. It is this that Sophocles' Antigone clearly means when she says that the burial of Polyneices was a just act in spite of the prohibition: she means that it was just by nature:

"Not of to-day or yesterday it is,

But lives eternal: none can date its birth."

And so Empedocles, when he bids us kill no living creature, he is saying that to do this is not just for some people, while unjust for others:

"Nay, but, an all-embracing law, through the realms of the sky

Unbroken it stretcheth, and over the earth's immensity."

Aristotle, Rhetoric