"Isn't what you call the Moral Law simply our herd
instinct and hasn't it been developed just like all our other instincts? Of course, we sometimes do feel just that sort
of desire to help another person: and no doubt that desire is due to the herd instinct. But feeling a
desire to help is quite different from feeling that you ought to help whether you want to or not.
Supposing you hear a cry for help from a man in danger.
You will probably feel two desires—one a desire to give help (due to your herd instinct), the other a
desire to keep out of danger (due to the instinct for self-preservation). But you will find inside you, in
addition to these two impulses, a third thing which tells you that you ought to follow the impulse to
help, and suppress the impulse to run away. Now this thing that judges between two instincts, that
decides which should be encouraged, cannot itself be either of them." -C.S. Lewis
This thing that judges between the two instincts is our conscience. Our conscience appeals to a a higher standard; a moral law. Where did that come from?