The Sung philosophers, while they extended the cosmogony by adding the map of the "Great Extreme," added also all the maps printed in the ordinary editions of the Yi-king. These maps are not found in any text, nor as prefatory matter are they earlier than the Sung. The Buddhists brought the notion of pictorial illustrations with them from India. Before their time the Chinese made very limited use of illustrated diagrams. Probably the Buddhists took the notion from the Greeks, subsequently to the age of Alexander, when Greeks were in juxtaposition with Hindoos and other Buddhist peoples in Bokharia, Cabul, Afghanistan, and the Punjab.

There were, however, sketches of star groups to the Sing-king, "Star classic" (by Kan and Shi) of the Han dynasty, and the strokes of the eight and sixty-four kwa in the Yi-king, Ts'an-t'ung-ki, and other works. The arithmetical combinations called Ho-t'u and Lo-shu were also probably represented by dots or stars. Geometrical diagrams were not known. Though Chen Kung was aware of the property of the right-angled triangle arithmetically, i.e., that the squares of three and four are together equal to the square of five, he never thought of expressing it by a diagram. It needed the Greek genius to initiate the conceptions of geometry.

The later Chinese writers were unconsciously influenced much more by Buddhism, a product of the Indo-European mind, than they ever acknowledged; and they would, under the impressions made on them, imitate the greater