A world of automata – of creatures that worked like machines – would hardly be worth creating.
Now God designed the human machine to run on Himself. He Himself is the fuel our spirits were designed to burn, or the food our spirits were designed to feed on. There is no other.
In reality, moral rules are directions for running the human machine. Every moral rule is there to prevent a breakdown, or a strain, or a friction, in the running of that machine. That is why these rules at first seem to be constantly interfering with our natural inclinations.