He was born stupid, and greatly increased his birthright.

If [science] tends to thicken the crust of ice on which, as it were, we are skating, it is all right. If it tries to find, or professes to have found, the solid ground at the bottom of the water it is all wrong. Our business is with the thickening of this crust by extending our knowledge downward from above, as ice gets thicker while the frost lasts; we should not try to freeze upwards from the bottom.

It is death, and not what comes after death, that men are generally afraid of.

A definition is the enclosing a wilderness of idea within a wall of words.

Youth is like spring, an over praised season more remarkable for biting winds than genial breezes. Autumn is the mellower season, and what we lose in flowers we more than gain in fruits.

There are two classes [of scientists], those who want to know, and do not care whether others think they know or not, and those who do not much care about knowing, but care very greatly about being reputed as knowing.

An obstinate man does not hold opinions, but they hold him; for when he is once possessed with an error, it is, like a devil, only cast out with great difficulty.