It is a common observation that those who dwell continually upon their expectations are apt to become oblivious to the requirements of their actual situation.

In all the works on pedagogy that ever I read — and they have been many, big, and heavy — I don't remember that any one has advocated a system of teaching by practical jokes, mostly cruel. That, however, describes the method of our great teacher, Experience.

If man were immortal he could be perfectly sure of seeing the day when everything in which he had trusted should betray his trust, and, in short, of coming eventually to hopeless misery. He would break down, at last, as every good fortune, as every dynasty, as every civilization does. In place of this we have death.

All the evolution we know of proceeds from the vague to the definite.

This branch of mathematics [Probability] is the only one, I believe, in which good writers frequently get results which are entirely erroneous.

There is not a single truth of science upon which we ought to bet more than about a million of millions to one.

The universe ought to be presumed too vast to have any character.