It is certain that there may be extraordinary mental activity with an extremely small absolute mass of nervous matter: thus the wonderfully diversified instincts, mental powers, and affections of ants are notorious, yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this point of view, the brain of an ant is one of the most marvelous atoms of matter in the world, perhaps more so than the brain of a man.

On seeing the marsupials in Australia for the first time and comparing them to placental mammals: “An unbeliever . . . might exclaim 'Surely two distinct Creators must have been at work'”

Multiply, vary, let the strongest live and the weakest die.

A mathematician is a blind man in a dark room looking for a black cat which isn't there.

I conclude that the musical notes and rhythms were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex.

To my deep mortification my father once said to me, "You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and all your family."

Mathematics seems to endow one with something like a new sense.