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] When we consider that there is no evidence of the use of cobalt by the Chinese for the decoration of their porcelain during Sung times, that indeed the use of colour apart from that of the glaze as a means of decoration appears to have been then unknown; but that, on the other hand, not long after the turmoil of the Mongol invasion and domination--a period during which the two countries, China and Persia, were so closely connected--we find the use of cobalt as a decoration _sous couverte_ firmly established, we may, I think, regard it as not improbable that it was from the Persians that the Chinese learned the new method of decoration.[38]