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.

People who have read a good deal rarely make great discoveries. I do not say this in excuse of laziness, but because invention presupposes an extensive independent contemplation of things.

The fly that doesn't want to be swatted is most secure when it lights on the fly-swatter.

If there were only turnips and potatoes in the world, someone would complain that plants grow the wrong way.

An hour-glass is a reminder not only of time's quick flight, but also of the dust to which we must at last return

Nothing reveals a man's character better than the kind of joke at which he takes offense.

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.