No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.

We must plan for freedom, and not only for security, if for no other reason than that only freedom can make security secure.

Our knowledge can only be finite, while our ignorance must necessarily be infinite.

It is impossible to speak in such a way that you cannot be misunderstood.

Those who promise us paradise on earth never produced anything but a hell.

We have become makers of our fate when we have ceased to pose as its prophets.