and yet they must be presented to us in a glass darkly, by means of a mirror in an enigma. But we must firmly believe in them; for if we did not, then, the whole science of mathematics, and, a fortiori, all science, would become nonsense, and we should be, in fact, madmen, living in a world of chaos.
The fact is that, by the nature of the case, man is not capable of absolute truth; neither in the heights nor in the depths. Let him go to the very elements of the simplest things of the life about him, and he will find himself in a net of contradictions, obscurities, mysteries. It is idle for him to declare himself a purely rational creature, living in a rational, demonstrable universe: it is not so. It is idle for him to say: "If you can explain this to me I will believe in it." If he pursue the matter to
