Taijitu

In Chinese philosophy, a taijitu (Chinese: 太極圖; pinyin: tàijítú; Wade–Giles: tʻai⁴chi²tʻu²) is a symbol or diagram (圖; tú) representing taiji (太極; tàijí; 'utmost extreme') in both its monist (wuji) and its dualist (yin and yang) forms. A taijitu in application provides a deductive and inductive theoretical model. Such a diagram was first introduced by Neo-Confucian philosopher Zhou Dunyi of the Song Dynasty in his Taijitu shuo (太極圖說).

The Fourth Daozang, a Taoist canon compiled in the 1440s CE during the Ming dynasty, has at least half a dozen variants of the taijitu. The two most similar are the Taiji Xiantiandao and wujitu (無極圖; wújítú) diagrams, both of which have been extensively studied since the Qing period for their possible connection with Zhou Dunyi's taijitu.

Ming-period author Lai Zhide (1525–1604) simplified the taijitu to a design of two interlocking spirals with two black-and-white dots superimposed on them, which became associated with the Yellow River Map. This version was represented in Western literature and popular culture in the late-19th century as the "Great Monad", and this depiction became known in English as the "yin-yang symbol" from the 1960s. The contemporary Chinese term for the modern symbol is referred to as "the two-part Taiji diagram" (太極兩儀圖).

Ornamental patterns with visual similarity to the "yin-yang symbol" are found in archaeological artefacts of European prehistory; such designs are sometimes descriptively dubbed "yin-yang symbols" in archaeological literature by modern scholars.