He only fears men who does not know them, and he who avoids them will soon misjudge them.

He who does not see the whole world in his friends, does not deserve that the world should hear of him.

The world of empirical morality consists for the most part of nothing but ill will and envy.

As soon as you are in a social setting, you better take away the key to the lock of your heart and pocket it; those who leave thekey in the lock are fools.

Doubt can only be removed by action.

Someday someone will write a pathology of experimental physics and bring to light all those swindles which subvert our reason, beguile our judgement and, what is worse, stand in the way of any practical progress. The phenomena must be freed once and for all from their grim torture chamber of empiricism, mechanism, and dogmatism; they must be brought before the jury of man's common sense.

Man's highest merit always is, as much as possible, to rule external circumstances and as little as possible to let himself be ruled by them.