Dumbness and silence are two different things.

We despair of changing the habits of men, still we would alter institutions, the habits of millions of men.

Doubt is the beginning, not the end, of wisdom.

Is any knowledge worthless? Try to think of an example.

Form may be of more account than substance. A lens of ice will focus a solar beam to a blaze.

Boundaries which mark off one field of science from another are purely artificial, are set up only for temporary convenience. Let chemists and physicists dig deep enough, and they reach common ground.

Nothing cools so fast as undue enthusiasm. Water that has boiled freezes sooner than any other.