Physicians had gone to their graves calling Pasteur a liar, a fool, or worse—without examining evidence which their “common sense” told them was impossible.

Don't ever become a pessimist... a pessimist is correct oftener than an optimist, but an optimist has more fun, and neither can stop the march of events.

There are two ways of forming an opinion. One is the scientific method; the other, the scholastic. To the scientific mind, experimental proof is all-important, and theory is merely a convenience in description, to be junked when it no longer fits. To the academic mind, authority is everything, and facts are junked when they do not fit theory.

Never tease an old dog; he might have one bite left.

Unarmed hand-to-hand fighting does not change through the ages; only the name changes, and it has only one rule: do it first, do it fast, do it dirtiest.

Most women are damn fools and children. But they've got more range than we've got. The brave ones are braver, the good ones are better - and the vile ones are viler, for that matter.

All men are created unequal.