In the Book of Changes, the two modes give rise to the four images, and the four images in turn give rise to the eight trigrams.
Tips
culture
Each of the 四象 guards one quarter of the sky and rules seven of the 二十八宿: 青龙 the east, 白虎 the west, 朱雀 the south and 玄武 the north. They also stand for the four seasons, and appear on Han roof tiles and bronze mirrors.
