It has been a wonderful century and except for the first quarter I have been able to contribute to physics in this century. I came in at a very exciting and promising time when... when quantum theory was formulated. One of the remarkable things is that the fundamental ideas of quantum theory as formulated by Schrödinger, Heisenberg, Pauli and Dirac, the fundamental quantum theory is unchanged. It's the same today as it was in 1926, and I think this is sort of a miracle. It has been as durable as Newton's theory of mechanics and... and as Einstein's theory of relativity. Then another thing is that together with this new ability of the fundamental theory, there have gone so many discoveries of new phenomena, predicted by the radioactivity which was discovered just about a hundred years ago. Going through one of... the experiments and then going to the development, mostly since 1933, of accelerators, nuclear reactions being made possible by accelerators, going first into the millions of electron volts and more recently into the billions of electron volts, and 100 billions of electron volts. It was a spectacular experimental development and it is remarkable that quantum mechanics invented in 1926, still is correct. We have no experiment which is in conflict with quantum mechanics.