Bagua (the eight trigrams)

The Yijing’s commentaries give the trigrams a mythical inventor. In the passage Legge translates, Fu Xi (also called Pao-hsi) looked up at the forms in the sky and down at the patterns on the earth, and “on this he devised the eight lineal figures of three lines each”. Legge calls Fu Xi the most ancient person mentioned with any definiteness in Chinese history, a figure about whom “much that is fabulous is current”.

Two ways of setting the eight in a ring are in use, and the evidence for them is centuries apart. The houtian (“after heaven”) ring, linked with King Wen, puts Zhen in the east, for spring and the beginning, and is read clockwise through the seasons, with Li, fire, in the south and Kan, water, in the north. François Louis, in the Harvard Journal of Asiatic Studies, finds it in part on two diviner’s boards, one from a tomb of the Eastern Han, and on a bronze mirror dated 758. It was still the norm at the Song court in 1118, when the emperor Huizong named his new garden in the north-east of Kaifeng Genyue, “Marchmount of Gen”, after the trigram the houtian ring places in the north-east. The xiantian (“prior to heaven”) ring, linked with Fu Xi, is credited to Shao Yong (1012–1077). It starts with Qian at the top and pairs each trigram with its opposite across the circle. By the twelfth century it was hailed, Louis writes, as “a sublime, naturally perfect arrangement”, and it is the ring that Ming and early Qing diagrams of the taiji set round the yin yang. As decoration it appears only from the Southern Song onwards; one of the earliest pieces is a silver cup of the mid-thirteenth century from the tomb of a Southern Song scholar.