The Persian ware of this time was the culminating example of an art that had been handed down from the Egyptians and the Assyrians. As a rule, among these races, the baser nature of the paste had been concealed by a more or less opaque coating either of a fine clay or ‘slip,’ or of a glaze rendered non-transparent by the addition of tin; it is on this coating that the decoration is painted, to be covered subsequently (in the first case at least, that of the slip ware) by a coating of glaze. It is to this large class, for the most part to the latter or stanniferous division, that nearly all the famous wares of the European renaissance belong, not only the Spanish and Italian majolica but the enamelled fayence of France and Holland as well. It was with the latter two wares that at a later date the porcelain of China was destined to come into competition. Each of these ceramic schools, the Eastern porcelain and the Western fayence, might in certain points claim advantages over the other, advantages both of a practical and of an æsthetic nature. For example, the glory of the Persian fayence of that day lay in its application to architecture, in the brilliant coating of tiles that covered the walls and the domes of the mosques and dwellings both inside and out. The Chinese have never succeeded in making tiles of any size with their porcelain. When used for the decoration of buildings the porcelain, or rather the earthenware, is always in the form of solid, moulded bricks.
But there is another matter with which the Chinese who visited Western Asia at that time cannot fail to have been struck--with the materials, I mean, at the command of the Persians, for the application of colour both under and over the glaze. Of the decorations over the glaze the most important were those given by their famous metallic lustres. This lustre, we now know, was the result of an ingenious process by which a film of copper, or sometimes of silver, was developed on the surface of the glaze.
The Chinese have never attempted anything of the kind, in part because such a method of adornment was foreign to their notions of what was fitting. For we must bear in mind that the influence of the literary tradition in China has always tended towards simplicity of means in their decorative arts, and has been opposed to anything like an ostentatious display of expensive materials. Any marked infringement of this sentiment, even on the part of an emperor, has always called forth a protest from the censors. Another cause which hindered the adoption of the lustre decoration by the Chinese may be found, no doubt, in the difficulties of its practical application. At that time the processes of the muffle-stove for decoration over the glaze were quite unknown to them.[36] But the Saracens, in Western Asia, were already in possession of another means of decorating their ware. This they found in the use of cobalt, especially as a material for painting a design on the paste before the application of the glaze. We find this colour at times on the tiles that lined their prayer-niches; these indeed date from a somewhat later time. But there is another variety of Saracenic ware of which a few specimens have survived. I refer to the vases and bowls covered with a thick alkaline glaze, and decorated, in part at least, _under the glaze_ with a design of black lines and some rude patches of blue. These rare vases were formerly classed as Siculo-Moorish, but later research has proved most of them to be of Persian or perhaps rather of Syrian or Mesopotamian origin. They appear to be the work of thirteenth century potters, and some of them may be of even earlier date.[37]