Any subject was fair game. “I refuse to accept however, the stupidity of the Stock Exchange boys, as an explanation of the trend of stocks,” he remarked to Ulam in 1939. “Those boys are stupid alright, but there must be an explanation of what happens, which makes no use of this fact.” This question led to his Theory of Games and Economic Behavior, written with Oskar Morgenstern during the war years, with von Neumann giving the project his diminishing spare time and Morgenstern contributing “the period of the most intensive work I’ve ever known.”
