I liked Johnny von Neumann and Wigner better, but I somehow liked the idea of a professorship, liked the idea to work with a man who needed me, because my mathematics was stronger than his. That I certainly could not have said in connection with Wigner and most certainly I could not have said it in connection with Johnny von Neumann, whose mathematics was clearly better than anybody's mathematics, at least at his time. That is how I got to the United States, in 1935. And how I started to teach quantum mechanics, to continue the same kind of work I did in Göttingen, I did in Copenhagen, I did in London. Quantum mehanics- mechanics, correspondence principle, what is new in physics, which at that time in the United States was less well understood than it was in Europe. And those physics exercises, those agreeable afternoon lectures that I gave for a few years at the George Washington University are probably the best time of my life.