"Hundreds and hundreds of years ago," said Mr. Croyden, "while the Egyptians, Assyrians, Greeks, and Romans were experimenting at pottery-making, the Chinese, inside their great walled country, were busy with the same task. In fact as far back as two thousand years before Christ the Chinese were famous potters, making earthenware of such fine quality that it was difficult to tell whether it was pottery or porcelain. For the two are quite different, you must remember, Theo. It is not enough to say that pottery is thick and porcelain thin, for much of the Chinese and Japanese pottery is very thin indeed. The difference lies in the clay itself, of which the ware is made. Do not forget that. Pottery is an opaque ware composed of various combinations of clay which afterward may or may not have a coating of glaze put over it. But genuine porcelain is made from a mixture of quite different materials--a mixture of decomposed feldspar known as kaolin, and petuntse." Mr. Croyden paused a moment. "There are of course so-called porcelains made from other ingredients; but we call them soft paste chinas, and do not rate them as true porcelains. Only a hard paste, or kaolin ware, is acknowledged by experts to be genuine porcelain. Now all this sounds very simple. By putting the kaolin and the petuntse together in the right proportions, moulding the clay, and afterward applying to it a glaze of some sort the Chinese made their porcelain, and very beautiful porcelain it was. Some day I will tell you more about it. This porcelain was not only very hard but was semi-translucent; by that I mean that if it was held to the light one could see the glow through it. It was not, of course, transparent like glass. These two qualities of hardness and translucence help us to distinguish porcelain from pottery." Again Mr. Croyden stopped. "For example, Canton ware, commonly known as Canton china, is not really china at all, but is instead a fine quality of stone, or earthenware, coated over with a slip or glaze containing porcelain. Nor is the exquisite Satsuma ware china; that too is a pottery." Theo listened intently. "Now all this time the Chinese kept the secret of how they made their wares to themselves, not sharing their knowledge with any outside peoples. Many a nation would have given almost anything to know from what materials the beautiful bowls, vases, and dishes were made. It would have saved years and years of the toil of patient men. But the Chinese had no mind to tell any one. Instead, they went on making more and more pottery and porcelain, improving their work with each successive generation. It is amusing to recall that while our ancestors in England were barbarians, and were eating out of the crudest clay vessels or from trenchers of wood, the Chinese were enjoying the luxury of the finest pottery and porcelain." Theo's eyes opened very wide.