This is about the time we made up the "Nebech index." Johnny [von Neumann] had told me the classic story of the little boy who came home from school in pre-World-War-I Budapest and told his father that he had failed his final examination. The father asked him, "Why? What happened?" The boy replied, "We had to write an essay. The teacher gave us a theme: the past, the present and the future of the Austro-Hungarian Empire." The father asked, "So, what did you write?" and the boy answered, "I wrote, Nebech, nebech, nebech." "That is correct," his father said, "Why did you receive an F?" "I spelled nebech with two bb's," was the answer.

This gave me the idea of defining the nebech index of a sentence as the number of times the word nebech could be inserted in it and still be appropriate, through giving a different flavor to the meaning of the sentence according to the word it qualifies. For instance, one could argue that the most perfect "nebech three" sentence is Descartes' statement: Cogito, ergo sum. One can say, Cogito nebech, ergo sum. Or Cogito, ergo nebech sum. Or Cogito, ergo sum nebech. Unfortunately this elegant example occurred to me only after Johnny's death. Johnny and I used this index frequently during mathematical talks, physics meetings or political discussions. We would nudge one another, whisper "Nebech two" at a particular statement, and enjoy this greatly.

Now, if the reader is sufficiently mystified, I will explain that "nebech" is an untranslatable Yiddish expression, a combination of commiseration, scorn, drama, ridicule.

To try to give the flavor of the word, imagine the William Tell story as acted out in a Jewish school. In the scene where William Tell waits in hiding to shoot Gessler, an actor says, in Yiddish: "Through this street the Nebech must come." It is obvious that Gessler is a Nebech since he will be the victim of William Tell. But if nebech had been in front of the word street, then the accent would be on street, indicating that it was not much of a street. To appreciate this may take years of apprenticeship.

(Adventures of a Mathematician / Stanislaw M. Ulam, pp. 194-195).