The conditions which produced such a community as this were ideal for the development of literature and art, and the Sung dynasty has been described as a prolonged Augustan age for poets, painters, and art workers of every persuasion. It was, moreover, an age of connoisseurs and collectors. Treatises were written on artistic subjects, encyclopædias were published, and illustrated catalogues issued by the order of the Emperor and his followers. Among the best known of these last publications are the _Hsüan Ho po ku t´u lu_, "Illustrated discussion of the antiquities in the palace of Hsüan Ho," and the _Ku yü t´u p´u_, "Illustrated description of ancient jade." It is true that modern criticism has seriously impugned the archæological value of both these classic works. It is said that ingenious conjectures and reconstructions, based on the reading of earlier literature, too often take the place of practical archæology and first-hand knowledge of the art of the Shang and Chou dynasties. Sung archæology, in fact, appears to have been in much the same theoretical condition as the Homeric criticism in Europe before the days of Schliemann. But for us these works must always have great interest, if only for the records they preserve of T´ang and Sung ideas. An excellent, if extreme, instance of the inherent weakness of Sung archæology is given by Laufer.[88] In describing certain objects of the Chou dynasty early writers had been in the habit of speaking of "grain pattern" and "rush pattern," assuming a knowledge in their readers which subsequent ages did not possess. In the Sung period the current ideas with regard to these patterns were expressed by the illustrator of the Sung edition of the _Li Chi_ by ornamenting jade discs, in the one case with ears of wheat and in the other with a clump of rushes. Modern archæologists have identified the patterns in question on objects found in Chou burials, the grain pattern being symbolically rendered by a number of small raised discs, representing either grains of corn or heaps of grain, and the rush pattern by a kind of matting diaper, geometrically drawn. This instance serves to illustrate the salient differences between the Chou and Sung art, the two extremes; the Chou art is symbolical and geometrical, the Sung impressionist and naturalistic. The Sung poets and painters[89] communed with Nature in the wilds and threw into their verse or on to their silks vivid impressions and ideal conceptions of the natural phenomena. The Chinese art of after years owes many of its noblest inspirations to Sung masters, but nowhere are these ideas developed with the same freshness and power as in the Sung originals.