Once I even took the train to Utrecht, forty miles from Amsterdam, with my yellow star, this star which I still have. Why did I go? I just wanted to visit some friends. I was a little bit crazy, a little bit insane.

The rule of the game was never assume that anybody, however honorable, would be able to stand up under torture. If Mr. X, who knew where I was, was caught for some reason, I should move.

One of the absolute rules I learned in the war was, don't know anything you don't need to know, because if you ever get caught they will get it out of you.

To make a discovery is not necessarily the same as to understand a discovery.

A number of current theoretical explorations will turn out to be passing fancies...

Deliberately or not, every author is of course present in every book he or she writes - even in a scientific text.

One of the things I learned, one of the strangest things, is how to think. There was nothing else to do. I couldn't see people, or go for a walk in the forest. All I had was my head and my books, and I thought a lot.