The great trick of regarding small departures from the truth as the truth itself - on which is founded the entire integral calculus - is also the basis of our witty speculations, where the whole thing would often collapse if we considered the departures with philosophical rigour.

I ceased in the year 1764 to believe that one can convince one’s opponents with arguments printed in books. It is not to do that, therefore, that I have taken up my pen, but merely so as to annoy them, and to bestow strength and courage on those on our own side, and to make it known to the others that they have not convinced us.

It is almost impossible to carry the torch of truth through a crowd without singeing somebody's beard.

There can hardly be a stranger commodity in the world than books. Printed by people who don't understand them; sold by people who don't understand them; bound, criticized and read by people who don't understand them; and now even written by people who don't understand them.

As the few adepts in such things well know, universal morality is to be found in little everyday penny-events just as much as in great ones. There is so much goodness and ingenuity in a raindrop that an apothecary wouldn't let it go for less than half-a-crown.

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

So-called professional mathematicians have, in their reliance on the relative incapacity of the rest of mankind, acquired for themselves a reputation for profundity very similar to the reputation for sanctity possessed by theologians.