Many years ago, when I was still a schoolboy in China, I had the unforgettable experience of reading translations of the books by Eddington and by Jeans about the new developments in physics. They described the various conceptual revolutions in 20th century physics, starting from the special theory of relativity, leading to the general theory and to quantum mechanics. I cannot say that I understood the meaning and the necessity of the Fitzgerald contraction, the Bohr atom, or the uncertainty principle, but it was impossible for me not to catch the excitement and the enthusiasm so vividly overflowing from the pages. It was clear that here was a new gate opening onto the mystery of the structure of the universe, at once full of light and darkness, enlightenment and puzzles. How much this fascination influenced my later choice of a career I could not say, because I do not know. But even today as I recall my experience so many years ago I could still feel the mysterious excitement that had then overwhelmed me.