I want to tell you another story about Bohr, a story that I want to tell you just for the sheer fun of it. For once, it has no meaning except to tell you what Bohr was. I listened to him once when he talked, mistakenly, about the oxygen molecule. One of my professors in Leipzig - Hund, Friedrich Hund - taught me about the simple molecules very accurately. Bohr did not know that and actually made some mistaken statements and I had to contradict. I wanted to be polite and I remember to have said to one of his statements- This is an exaggeration. Thereupon Bohr stares at me, quite mad- Teller says I'm exaggerating. Teller does not want me to exaggerate. Well, if I can't exaggerate, I can't speak. We then talked about the objective questions and I think it was cleared up. But Bohr's statement about contradictions, about the use of words, about exaggeration, has something to do with the spirit of the uncertainty principle and the spirit of the times. And also, the spirit of one of the clear statements of moral significance that Bohr liked to make. Everybody - young people at eighteen years - should know that no statement can be believed unless you understand the statement and its opposite. A contradiction is not only likable, a contradiction is basic to understanding.