"on his first visit to the Los Alamos Tech Area, when he had encountered von Neumann discussing theory with dark, intense Edward Teller, the "tremendously long formulae on the blackboard" had scared him. "Seeing all these complications of analysis, I was dumbfounded, fearing I would never be able to contribute anything." But the equations stayed on the board from day to day, which meant to Ulam that the pace of invention was relatively slow, and he soon regained confidence.1340 "I found out that the main ability to have was a visual, and also an almost tactile, way to imagine the physical situations, rather than a merely logical picture of the problems."