Q,. But it is easy enough to see that a theorem is unlikely to be serious when it lacks these qualities conspicuously; we have only to take examples from the isolated curiosities in which arithmetic abounds. Aubyn' which had fired his youthful imagination, he found he did not really enjoy lingering in the combination-room over port and walnuts. We can see this even in semi-historic civilizations. This view has been held, in one form or another, by many philosophers of high reputation from Plato onwards, and I shall use the language which is natural to a man who holds it. Partly because of that incident, his religious disbelief remained open and active ever after. My next two sections will have a mildly philosophical flavour. That was true in any argument I had with him. 'The certainty of mathematics', says Whitehead1, 'depends on its complete abstract generality. There he sat