Now this Law or Rule about Right and Wrong used to be called the Law of Nature.  Nowadays, when we talk of the 'laws of nature' we usually mean things like gravitation, or heredity, or the laws of chemistry.  But when the older thinkers called the Law of Right and Wrong the 'Law of Nature', they really meant the Law of Human Nature. The idea was that, just as all bodies are governed by the law of gravitation, and organisms by biological laws, so the creature called man also had his law--with this great difference, that a body could not choose whether it obeyed the law of gravitation or not, but a man could choose either to obey the Law of Human Nature or to disobey it.