Imagine the world so greatly magnified that particles of light look like twenty-four-pound cannon balls.

The natural scientists of the previous age knew less than we do and believed they were very close to the goal: we have taken very great steps in its direction and now discover we are still very far away from it. With the most rational philosophers an increase in their knowledge is always attended by an increased conviction of their ignorance.

Cautiousness in judgment is nowadays to be recommended to each and every one: if we gained only one incontestable truth every ten years from each of our philosophical writers the harvest we reaped would be sufficient.

Everyone is a genius at least once a year.

A book which, above all others in the world, should be forbidden, is a catalogue of forbidden books.

I am convinced we do not only love ourselves in others but hate ourselves in others too.

What is called an acute knowledge of human nature is mostly nothing but the observer's own weaknesses reflected back from others.