The disagreement between Niels Bohr and Albert Einstein about quantum physics has been told so often that one can ask himself what was it all about. I can recall Bohr's answer to a question of an old friend of his about where's the electron, where can the electron be said to be? And Bohr's answer- to be, to be, what does it mean, to be? And Einstein had the feeling that things exist out there independent of us, that no observation is required. It's one of the great disagreements of all time. And the Institute for Advanced Study had invited Niels Bohr to spent the spring semester of 1939 at the institute. It would have been so wonderful to have day-by-day, Bohr and Einstein arguing with each other, because it could not have helped to- it would have given a wonderful help to understand this greatest of all mysteries, the quantum. But it was not to be. Just as Bohr was leaving Copenhagen on this trip, taking along his assistant, Rosenfeld, and his son, Eric, he received a visit from Frisch, the refugee from Germany that I had met six years before, telling about the discovery of the Fission of Uranium. And Bohr immediately said- oh, how could it have been otherwise? Oh, what fools we've all been. Pacing up and down on the ship on the way over, thinking about nuclear fission. At any rate, I was down at the pier in New York to meet him, simply because of the happy times I'd had with him in Copenhagen. That was January 16th, 1939, when the Swedish-America steamboat, Drottningholm, pulled into the harbor of New York. And Enrico Fermi and his wife, Laura, were there also to meet him. Bohr and his son stayed overnight in New York, but Rosenfeld came down with me on the train to Princeton. That was a Monday, and Monday night I was in charge of a journal club that met at seven o'clock, from seven to nine o'clock every Monday, to talk about recent things in physics. I had to get together three reports. And here Rosenfeld was telling me about this fission business. I said- you've got to talk at our journal club tonight. And so he did. Caused great excitement. That was the first word of fission in America. The next day, Bohr arrived, he was very unhappy that Frisch had talked about this- that Rosenfeld had talked about this because Frisch had not yet published his paper on the subject, and if he didn't publish it first, somebody else might scoop him. But Bohr was always anxious for the person who made a discovery to get the credit for the discovery.