Good tests kill flawed theories; we remain alive to guess again.

The survival value of intelligence is that it allows us to extinct a bad idea, before the idea extincts us.

It is wrong and dangerous to extol freedom by telling people that they will certainly be all right once they are free. The most we can say of democracy or freedom is that they give our personal abilities a little more influence on our well-being.

If you can't say it simply and clearly, keep quiet, and keep working on it till you can.

The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance

There is no history, only histories.

The best thing that can happen to a human being us to find a problem, to fall in love with that problem, and to live trying to solve that problem, unless another problem even more lovable appears.