At the age of eleven, I began Euclid, with my brother as my tutor. ... I had not imagined that there was anything so delicious in the world. After I had learned the fifth proposition, my brother told me that it was generally considered difficult, but I had found no difficulty whatsoever. This was the first time it had dawned on me that I might have some intelligence.

Organic life, we are told, has developed gradually from the protozoon to the philosopher, and this development, we are assured, is indubitably an advance. Unfortunately it is the philosopher, not the protozoon, who gives us this assurance.

The good life is one inspired by love and guided by knowledge.

If we were all given by magic the power to read each other’s thoughts, I suppose the first effect would be almost all friendships would be dissolved; the second effect, however, might be excellent, for a world without any friends would be felt to be intolerable, and we should learn to like each other without needing a veil of illusion to conceal from ourselves that we did not think each other absolutely perfect.

We are all prone to the malady of the introvert who with the manifold spectacle of the world spread out before him, turns away and gazes only upon the emptiness within.

Great God in Boots! – the ontological argument is sound!

The first man who said "fire burns" was employing scientific method, at any rate if he had allowed himself to be burnt several times. This man had already passed through the two stages of observation and generalization. He had not, however, what scientific technique demands - a careful choice of significant facts on the one hand, and, on the other hand, various means of arriving at laws otherwise than my mere generalization.