I have often noticed that when people come to understand a mathematical proposition in some other way than that of the ordinary demonstration, they promptly say, "Oh, I see. That's how it must be." This is a sign that they explain it to themselves from within their own system.

As I take up my pen I feel myself so full, so equal to my subject, and see my book so clearly before me in embryo, I would almost like to try to say it all in a single word.

The greater part of human misery is caused by indolence.

The most successful tempters and thus the most dangerous are the deluded deluders.

We have to believe that everything has a cause, as the spider spins its web in order to catch flies. But it does this before it knows there are such things as flies.

Virtue by premeditation isn't worth much.

The course of the seasons is a piece of clockwork, with a cuckoo to call when it is spring.