I got an invitation to a Pan-American Congress — to which I was determined not to go — in Washington, next door. And Roosevelt was going to speak and I still was not going. But the day before his speech, Hitler invaded the Lowlands and it was very clear that the decisions in the World War were now immediately impending. And Roosevelt was going to speak about that, so I was going. The first and only time that I saw Roosevelt, and that was from a distance. He talked about the fact that the time to fly from Europe to the American continent was not so great, that small nations are not secure, neither are big ones, that the scientists may be blamed for the horrible things that are happening. “But,” said Roosevelt, “I am a pacifist, and you, my friends, are pacifists, but I am telling you, if you are not going to work on the instruments of war, freedom will be lost everywhere.” That was the question on my mind. And I had the impression that Roosevelt was talking to me. And of course that was stupid to think so — me of 2,000 people — but yes, me. Because, of a couple of thousand people present, it may have been he and I and none other who knew about the possibility of the atomic bomb. I read the letter that he read, and I knew the actions that he had already taken to start work on nuclear explosives. When he finished talking, my mind was made up. And I remember looking at my watch; he had talked 20 minutes.