If I put six pennies into a drawer on Monday and six more on Tuesday, the laws decree that – other things being equal – I shall find twelve pennies there on Wednesday. But if the drawer is has been robbed I may in fact find only two. Something will have been broken (the lock of the drawer or the laws of England) but the laws of arithmetic will not have been broken.
Lewis, C. S. (1947) ‘Miracles’ ‘Chapter 8: Miracles and the Laws of Nature’ p 60
This perhaps helps to make a little clearer what the laws of Nature really are. We are in the habit of talking as if they caused events to happen; but they have never caused any event at all. The laws of motion do not set billiard balls moving: they analyse the motion after something else (say, a man with a cue, or a lurch of the liner, or, perhaps, supernatural power) has provided it. They produce no events: they state the pattern to which every event – if only it can be induced to happen – must conform, just as the rules of arithmetic state the pattern to which all transactions with money must conform – if only you can get hold of any money. Thus in one sense the laws of Nature cover the whole field of space and time; in another, what they leave out is precisely the whole real universe – the incessant torrent of actual events which makes up true history. That must come from somewhere else. To think the laws can produce it is like thinking that you can create real money by simply doing sums. For every law, in the last resort, says ‘If you have A, then you will get B’. But first catch your A: the laws won’t do it for you.
Lewis, C. S. (1947) ‘Miracles’ ‘Chapter 8: Miracles and the Laws of Nature’ p 61s