This is an interesting way to describe free will (or whatever it is that Man has):
No code is necessary to control the behaviour of matter, since matter is apparently not tempted to contradict its own nature, but obeys the law of its being in perfect freedom. Man, however, does continually suffer this temptation and frequently yields to it. This contradiction within his own nature is peculiar to man, and is called by the Church “sinfulness”; other psychologists have other names for it.
-Dorothy Sayers, The Mind of the Maker, Ch.1