A study of family portraits is enough to convert a man to the theory of reincarnation.

Dogs don't make mistakes.

Well, I'm a bacteriologist, you know. I live in a nine-hundred-diameter microscope. I can hardly claim to take serious notice of anything that I can see with my naked eye.

Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner.

When you have one of the first brains of Europe up against you, and all the powers of darkness at his back, there are infinite possibilities.

Mediocrity knows nothing higher than itself, but talent instantly recognizes genius.

It is a mistake to confound strangeness with mystery.