The vitreous enamels of the Chinese were of course used as glazes on their porcelain wares and pottery, but it seems that formerly they only made glass objects in the imitation of precious stones, gems, and in their enamels. Chinese glass is often made to simulate rock crystal and jade carvings; their glass snuff-boxes and other small objects are usually well coloured, and are decorated with relief work of ornament, landscapes or figure subjects, the objects generally being of a massive character (Fig. 309). CHAPTER IX. THE DECORATION OF BOOKS. Books may be illustrated in a more or less pictorial manner without any particular regard to the decoration of the page, or with due regard to its ornamentation. In the latter case the designer of the decoration will be the illustrator and decorator in one. The great majority of modern illustrated books are not decorated in the true sense of the word, but have their illustrations inserted as pictures, or scraps of pictures, without borders or frames, and with little or no relation to the distribution of the printed matter or to the boundary lines of the page. In this respect the modern practice is different from that observed in the Mediæval and Renaissance book illustration, for in the two periods named, when a purely literal or pictorial scene was inserted, it had usually borders like mouldings, or borders of rich decoration, or sometimes bands and lines only, which separated the picture from the printed or written text, and harmonized with any other decoration that might be on the page. Thus an artistic unity was usually preserved in the book decoration of earlier times, which, generally speaking, is the exception in the present day, and not the rule. The modern practice was brought about by the invention of copper-plate engraving—about 1477—when the copper-plate illustration became, in a great measure, the substitute for wood-engraved blocks of a former period. The plates were usually engraved with copies of pictures, and the book decorator was superseded by the painter; the art and practice of the former declined, while the work of the latter became fashionable, and has remained so ever since. Photography has been a considerable aid to the pictorial side of book illustration, and has, on the other hand, been a great help to designers of decorative illustration, for by the use of photography the designer is enabled to have the work of his hand reproduced in facsimile, as in the process block method, which has been such a powerful rival and competitor to all kinds of engraving that it has now almost crushed them out of existence. Before the invention of printing books were very scarce, as they were written in manuscript, and were mostly of a devotional character, made for the use of the clergy and others in monastic establishments or religious houses.