Neither Dirac nor von **Neumann** discussed his measurements in physical terms.

— W. E. Lamb, Classical measurements on a quantum mechanical system,

Use "entropy" and you can never lose a debate, von **Neumann** told Shannon - because no one really knows what "entropy" is.

— Part One, Entropy, Randomness, Disorder, Uncertainty, p. 57

As a mathematician, von **Neumann** was quick, brilliant, efficient, and enormously broad in scientific interests beyond mathematics itself. He knew his technical abilities; his virtuosity in following complicated reasoning and his insights were supreme; yet he lacked absolute self confidence.

— Chapter 4, Princeton Days, p. 76

In desperation I asked Fermi whether he was not impressed by the agreement between our calculated numbers and his measured numbers. He replied, "How many arbitrary parameters did you use for your calculations?" I thought for a moment about our cut-off procedures and said, "Four." He said, "I remember my friend Johnny von **Neumann** used to say, with four parameters I can fit an elephant, and with five I can make him wiggle his trunk." With that, the conversation was over.

— "A meeting with Enrico Fermi" in

[John] von **Neumann** gave me an interesting idea: that you don't have to be responsible for the world that you're in. So I have developed a very powerful sense of social irresponsibility as a result of von **Neumann**'s advice. It's made me a very happy man ever since. But it was von **Neumann** who put the seed in that grew into my active irresponsibility!

— Part 3: "Feynman, The Bomb, and the Military", "Los Alamos from Below", p. 132

A great deal of study has been directed to denning 'best decisions,' particularly since the pioneering work of mathematical statisticians (such as Wald), of mathematicians (such as von **Neumann**), of economists (such as Arrow )... The main effect of this development on the practice of OR has been the growing realization that there are decision objectives other than maximizing expected return and minimizing maximum loss. That is, in many practical situations there are criteria of optimality that are more appropriate than these two mentioned.

— p. 270 (The development of operations research as a science, 1956)

By the end of the war the new game theoretic methods that had been developed by von **Neumann** and Morgenstern were added to the toolkit and mathematical techniques that operations research scientists deployed. These proved very valuable, and game theoretic approaches took on great importance after the war.

— M. Fortun, and S.S. Schweber (1993) "Scientists and the Legacy of World War II: The Case of Operations Research (OR)."

By the end of the war the new game theoretic methods that had been developed by von **Neumann** and Morgenstern were added to the toolkit and mathematical techniques that operations research scientists deployed. These proved very valuable, and game theoretic approaches took on great importance after the war.

— M. Fortun, and S.S. Schweber (1993) "Scientists and the Legacy of World War II: The Case of Operations Research (OR)."