I observed that learned men in spectacles were talking of the actual things that happened – dawn and death and so on – as if they were rational and inevitable. They talked as if the fact that trees bear fruit were just as necessary as the fact that two and one trees make three. But it is not…You cannot imagine two and one not making three. But you can easily imagine trees not growing fruit; you can imagine them growing golden candlesticks or tigers hanging on by the tail. These men in spectacles spoke much of a man named Newton, who was hit by an apple, and who discovered a law. But they could not be got to see the distinction between a true law, a law of reason, and the mere fact of apples falling. If the apple hit Newton’s nose, Newton’s nose hit the apple. That is a true necessity: because we cannot conceive the one occurring without the other. But we can quite well conceive the apple not falling on his nose; we can fancy it flying ardently through the air to hit some other nose, of which it had a more definite dislike.
– G.K. Chesterton, Orthodoxy, p. 56.