We never know what we are talking about.

Serious rational criticism is so rare that it should be encouraged. Being too ready to defend oneself is more dangerous than being too ready to admit a mistake.

The game of science is, in principle, without end. He who decides one day that scientific statements do not call for any further test, and that they can be regarded as finally verified, retires from the game.

Science must begin with myths, and with the criticism of myths.

We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.

I have spoken to Einstein and he admitted to me that his theory was in fact no different from the one of Parmenides.

It is not possible to write clearly enough to avoid being misrepresented by people who are sufficiently determined to do so.