No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it

The defence of democracy must consist in making anti-democratic experiences too costly for those who try them; much more costly than a democratic compromise

The war of ideas is a Greek invention. It is one of the most important inventions ever made. Indeed, the possibility of fighting with with words and ideas instead of fighting with swords is the very basis of our civilization, and especially of all its legal and parliamentary institutions.

Nature consists of facts and of regularities, and is in itself neither moral nor immoral. It is we who impose our standards upon nature, and who in this way introduce morals into the natural world, in spite the fact that we are part of this world. We are products of nature, but nature has made us together with our power of altering the world, of foreseeing and of planning for the future, and of making far-reaching decisions for which we are morally responsible. Yet, responsibility, decisions, enter the world of nature only with us

Better our hypotheses die for our errors than ourselves.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.

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