How can an unchanging system survive the continual increase of knowledge? Now, in certain cases we know very well how it can. A mature scholar reading a great passage in Plato, and taking in at one glance the metaphysics, the literary beauty, and the place of both in the history of Europe, is in a very different position from a boy learnng the Greek alphabet. Yet through that unchanging system of the alphabet all this vast mental and emotional activity is operating. It has not been broken by the new knowledge. It is not outworn. If it changed, all would be chaos. A great Christian statesman, considering the morality of a measure which will affect millions of lives, and which involves economic, geographical and political considerations of the utmost complexity, is in a different position from a boy first learning that one must not cheat or tell lies, or hurt innocent people. But only in so far as that first knowledge of the great moral platitudes survives unimpaired in the statesman will his deliberation be moral at all. If that goes, then there has been no progress, but only mere change. For change is not progress unless the core remains unchanged. A small oak grows into a big oak: if it became a beech, that would not be growth, but mere change. And thirdly, there is a great difference between counting apples and arriving at the mathematical formulae of modern physics. But the multiplication table is used in both and does not grow out of date….

The very real possibility of progress demands that there should be an unchanging element. New bottles for new wine, by all means: but not new palates, throats and stomachs, or it would not be, for us, ‘wine’ at all. I take it we should all agree to find this sort of unchanging element in the simple rules of mathematics. I would add to these the primary principles of morality. And I would also add the fundamental doctrines of Christianity. To put it in rather more technical language, I claim that the positive historical statements made by Christianity have the power, elsewhere found chiefly in formal principles, of receiving, without intrinsic change, the increasing complexity of meaning which increasing knowledge puts into them.