Now, I would like to tell you a few stories about the same period. It was a wonderful period, a period full of new discoveries, full of new, new knowledge. And also full of people who have understood what is going on only in part. I want to tell you one story involving myself. Heisenberg, from time to time, recommended to his students to go up to Berlin, to the Kaiser Wilhelm Institute, and listen to some iner-interesting talks. And so, on his advice, with all of my 21 or 22 years, I went to listen to a lecture by Einstein, of his later theories in which he explains relativity and electromagnetism with the same ideas. I listened carefully and I understood everything for the first 30 seconds. And after that I understood less and less and less. And when in the end he finished and some of us including Eugene Wigner went to talk- went to walk in the zoological garden, beautiful sunshine, there I was completely desperate. And Eugene, an old friend and a very kind person, comes to me- What's the matter? And I answered him, in Hungarian, in very simple terms. I said- I am so stupid. And now, Wigner basically, very basically, the kindest of all men, should have contradicted me but he didn't. He said- Yes, stupidity is a general human property. Now, you know, the remarkable thing is that, that, that he made me feel much better. That sounded like the truth- All right, I'm stupid; so is everybody else. The point that I did not know then but I know now, that among the people who did not understand what Einstein was saying was Einstein himself. He did wonderful things until 1920, at which time I don't know, he was not yet forty years old, I believe. After that he tried to explain everything and did not succeed.