No slave is a slave to the same lengths, and in so full a sense of the word, as a wife is.

It often happens that the universal belief of one age of mankind — a belief from which no one was, nor without an extraordinary effort of genius and courage, could at that time be free — becomes to a subsequent age so palpable an absurdity, that the only difficulty then is to imagine how such a thing can ever have appeared credible.

He who lets the world choose his plan of life for him has need of no other faculty than that of ape-like imitation.

A man of clear ideas errs grievously if he imagines that whatever is seen confusedly does not exist; it belongs to him, when he meets with such a thing, to dispel the midst, and fix the outlines of the vague form which is looming through it.

There is nothing which an untrained mind shows itself more hopelessly incapable, than in drawing the proper general conclusions from its own experience. And even trained minds, when all their training is on a special subject, and does not extend to the general principles of induction, are only kept right when there are ready opportunities of verifying their inferences by facts.

The peculiarity of the evidence of mathematical truths is that all the argument is on one side.

Men and governments must act to the best of their ability. There is no such thing as absolute certainty but there is assurance sufficient for the purposes of human life.