Taijitu Taijitu A taijitu () is a symbol or diagram ( "tú") in Chinese philosophy representing Taiji ( "tàijí" "great pole" or "supreme ultimate") representing both its monist ("wuji") and its dualist (yin and yang) aspects. Such a diagram was first introduced by Song Dynasty philosopher Zhou Dunyi (周敦頤 1017–1073) in his "Taijitu shuo" 太極圖說. The modern Taoist canon, compiled during the Ming era, has at least half a dozen variants of such "taijitu". The two most similar are the "Taiji Primal Heaven" (太極先天圖 "tàijí xiāntiān tú") and the "wuji" (無極圖 "wújí tú") diagrams, both of which have been extensively studied
Yin and yang "to shelter; shade", and 陽 or 阳 "sunny" is always pronounced with rising second tone "yáng". Sinologists and historical linguists have reconstructed Middle Chinese pronunciations from data in the (7th century CE) "Qieyun" rhyme dictionary and later rhyme tables, which was subsequently used to reconstruct Old Chinese phonology from rhymes in the (11th-7th centuries BCE) "Shijing" and phonological components of Chinese characters. Reconstructions of Old Chinese have illuminated the etymology of modern Chinese words. Compare these Middle Chinese and Old Chinese (with asterisk) reconstructions of "yīn" 陰 and "yáng" 陽: Schuessler gives probable Sino-Tibetan etymologies for both Chinese words. "Yin"