Whatever we succeed in doing is a transformation of something we have failed to do. Thus, when we fail, it is only because we have given up.

Science means simply the aggregate of all the recipes that are always successful. All the rest is literature.

The purpose of psychology is to give us a completely different idea of the things we know best.

Cognition reigns but does not rule.

One should be light like a bird, and not like a feather.

It is a law of nature that we defend ourselves from one affection only by means of another.

The great virtues of the German people have created more evils than idleness ever did vices