At one time I had undertaken to write a book on von Neumann’s scientific life. In trying to plan it, I thought of how I, along with many others, had been influenced by him; and how this man, and some others I knew, working in the purely abstract realm of mathematics and theoretical physics had changed aspects of the world as we know it. […] It is still an unending source of surprise for me to see how a few scribbles on a blackboard or on a sheet of paper could change the course of human affairs.

Stanisław Ulam, Adventures of a Mathematician, New York, 1976, pp. 4-5