Defy the commandments of the natural law, and the race will perish in a few generations; co-operate with them, and the race will flourish for ages to come. That is the fact; whether we like it or not, the universe is made that way.  This commandment is interesting because it specifically puts forward the moral law as the basis of the moral code: because God has made the world like this and will not alter it, therefore you must not worship your own fantasies, but pay allegiance to the truth. - Dorothy Sayers, "The Mind of the Maker"

This.