"I well remember the time, after the First World War, when one needed a tillion-mark note to buy a dozen eggs. Since paper, however, was still valuable, the bank notes were stored in gigantic silos which stood in the yards of our factories. In these we children made tunnels and played among the billions and trillions — a strange introduction to money, but perhaps it helped me to realize how worthless it can become when man-made values change."