We now come to the important question of the classification of Chinese porcelain. A difficulty here arises from the rival claims of two systems. The older and perhaps safer division depends solely on the nature of the ware, its colour, decoration, etc.; but in opposition to this the claim of the more logical, historical classification has, with our increasing knowledge, become of late years more pressing. The result has been an attempt to combine the two systems. Such an attempt must necessarily lead to many compromises, and yet something of the sort is perhaps the only available plan. We may compare the development of the ceramic art in China to what has taken place in the evolution of the animal kingdom: while new and more elaborated forms are evolved, the older ones, or many of them, survive in but slightly modified forms. If this tendency be borne well in mind there will be less danger of confusion between the really old types and the modern representations or even copies which are called, in China, by the same names. The three classes into which Chinese porcelain is divided--and there is a general agreement among collectors on this head--rest on such an attempt to combine a historical with a technical classification:-- 1. Porcelain with single-coloured glazes, including plain white ware. The colour of the glaze is derived from two metals only, iron and copper. Any further decoration depends upon the moulding of the surface or upon patterns incised in the paste. All the wares made up to the end of the Sung period (1279 A.D.) may probably be included in this class. 2. Porcelain decorated with colour under the glaze. This division is nearly equivalent to our ‘blue and white’ ware, but in addition to cobalt, copper is at times introduced to give a red colour. This system of decoration was probably introduced during the course of the fourteenth century, and it is associated with the Ming dynasty. 3. Porcelain decorated with enamels over the glaze, necessitating a second firing in a muffle-stove. The use of these fusible enamel colours came in probably during the sixteenth century, but the art was not fully developed till much later. The glazes of the first and second classes as a rule contained no lead, and to melt them the full heat of the oven, the _grand feu_, was required.