Love has been taken away from the poets, and has been brought within the domain of true science. It may prove to be one of the great cosmic elementary forces. When the atom of hydrogen draws the atom of chlorine towards it to form the perfected molecule of hydrochloric acid, the force which it exerts may be intrinsically similar to that which draws me to you. Attraction and repulsion appear to be the primary forces. This is attraction.

It is a mistake to confound strangeness with mystery.

"I have seen those symptoms before," said Holmes, throwing his cigarette into the fire. "Oscillation upon the pavement always means an affaire de coeur."

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.

Hot hate is twin brother to hot love.

Some people's affability is more deadly than the violence of coarser souls.

For strange effects and extraordinary combinations we must go to life itself, which is always far more daring than any effort of the imagination.