All our thinking is of this nature, a free play with concepts.

Human beings are not condemned, because of their biological constitution, to annihilate each other or to be at the mercy of a cruel, self-inflicted fate.

Is there not a certain satisfaction in the fact that natural limits are set to the life of the individual, so that at the conclusion it may appear as a work of art?

When a man is sufficiently motivated, discipline will take care of itself.

But there is another reason for the high repute of mathematics: it is mathematics that offers the exact natural sciences a certain measure of security which, without mathematics, they could not attain.

Convictions can best be supported with experience and clear thinking.

To be free means to be independent, not to be influenced by what others think and say.