I lived altogether in nine different places while in hiding, because whenever something happened, either someone betrayed the place or something happened to someone who knew where I was, I had to move. 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.

On life in hiding from Nazi authorities during World War II, p. 48 - To Save A Life : Stories of Holocaust Rescue (2000)