A smile happens in a flash, but its memory can last a lifetime.

You may reasonably expect a man to walk a tightrope safely for ten minutes; it would be unreasonable to do so without accident for two hundred years.

I've made an odd discovery. Every time I talk to a savant I feel quite sure that happiness is no longer a possibility. Yet when I talk with my gardener, I'm convinced of the opposite.

The world in which we live can be understood as a result of muddle and accident; but if it is the outcome of deliberate purpose, the purpose must have been that of a fiend. For my part, I find accident a less painful and more plausible hypothesis.

Inferences of Science and Common Sense differ from those of deductive logic and mathematics in a very important respect, namely, when the premises are true and the reasoning correct, the conclusion is only probable.

Very few men can be genuinely happy in a life involving continual self-assertion against the skepticism of the mass of mankind, unless they can shut themselves up in a coterie and forget the cold outer world. The man of science has no need of a coterie, since he is thought well of by everybody except his colleagues. The artist, on the contrary, is in the painful situation of having to choose between being despised and being despicable.

If we compare Europe with other continents, it is marked out as [another] persecuting continent.