A taijitu (Traditional Chinese: 太極圖; Simplified Chinese: 太极图; Pinyin: tàijítú; Wade-Giles: t'ai⁴chi²t'u²) is a symbol or diagram (图 tú) in Chinese philosophy representing Taiji (太极 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 Zhou Dunyi (周敦頤 1017–1073) in his the Taijitu shuo 太極圖說.
The modern Daoist 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 during 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. In the Ming era, the combination of the two interlocking spirals of the taijitu with two black-and-white dots superimposed on them became identified with the He tu or "Yellow River diagram" (河圖). It is this version that has been widely popularised as the "yin-yang symbol" in the West since the 1960s. The contemporary Chinese term for the modern symbol is 太极兩儀图 "two-part Taiji diagram".
Unicode features the "yin-yang symbol" in the Miscellaneous Symbols block, at code point U+262F (YIN YANG ☯). The related "double body symbol" is included at U+0FCA (TIBETAN SYMBOL NOR BU NYIS -KHYIL ࿊), in the Tibetan block.
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.
The taijitu consists of five parts. Strictly speaking the "yin and yang symbol", itself popularly called taijitu, represents the second of these five parts of the diagram.
- At the top, an empty circle depicts the absolute (Wuji)
- A second circle represents the Taiji as harboring Dualism, yin and yang, represented by filling the circle in a black-and-white pattern. In some diagrams, there is a smaller empty circle at the center of this, representing Emptiness as the foundation of duality.
- Below this second circle is a five-part diagram representing the Five Agents (Wuxing), representing a further stage in the differentiation of Unity into Multiplicity. The Five Agents are connected by lines indicating their proper sequence, Wood (木) → Fire (火) → Earth (土) → Metal (金) → Water (水).
- The circle below the Five Agents represents the conjunction of Heaven and Earth, which in turn gives rise to the "ten thousand things". This stage is also represented by the Eight Trigrams (Bagua).
- The final circle represents the state of multiplicity, glossed "The ten thousand things are born by transformation" (生化物萬; modern 化生万物)
The term taijitu in modern Chinese is commonly used to mean the simple "divided circle" form (), but it may refer to any of several schematic diagrams that contain at least one circle with an inner pattern of symmetry representing yin and yang.
While the concept of yin and yang dates to Chinese antiquity, the interest in "diagrams" (圖 tú) is an intellectual fashion of Neo-Confucianism during the Song period (11th century), and it declined again in the Ming period, by the 16th century.
The original description of a taijitu is due to Song era philosopher Zhou Dunyi (1017–1073), author of the Taijitu shuo 太極圖說 "Explanation of the Diagram of the Supreme Ultimate", which became the cornerstone of Neo-Confucianist cosmology. His brief text synthesized aspects of Chinese Buddhism and Taoism with metaphysical discussions in the Yijing.
Non-polar (wuji) and yet Supreme Polarity (taiji)! The Supreme Polarity in activity generates yang; yet at the limit of activity it is still. In stillness it generates yin; yet at the limit of stillness it is also active. Activity and stillness alternate; each is the basis of the other. In distinguishing yin and yang, the Two Modes are thereby established. The alternation and combination of yang and yin generate water, fire, wood, metal, and earth. With these five [phases of] qi harmoniously arranged, the Four Seasons proceed through them. The Five Phases are simply yin and yang; yin and yang are simply the Supreme Polarity; the Supreme Polarity is fundamentally Non-polar. [Yet] in the generation of the Five Phases, each one has its nature.
Instead of usual Taiji translations "Supreme Ultimate" or "Supreme Pole", Adler uses "Supreme Polarity" (see Robinet 1990) because Zhu Xi describes it as the alternating principle of yin and yang, and …
insists that taiji is not a thing (hence "Supreme Pole" will not do). Thus, for both Zhou and Zhu, taiji is the yin-yang principle of bipolarity, which is the most fundamental ordering principle, the cosmic "first principle." Wuji as "non-polar" follows from this.
Since the 12th century, there has been a vigorous discussion in Chinese philosophy regarding the ultimate origin of Zhou Dunyi's diagram. Zhu Xi (12th century) insists that Zhou Dunyi had composed the diagram himself, against the prevailing view that he had received it from Daoist sources. Zhu Xi could not accept a Daoist origin of the design, because it would have undermined the claim of uniqueness attached to the Neo-Confucian concept of dao.
Zhao Huiqian (趙撝謙, 1351–1395) was the first to introduce the "swirling" variant of the taijitu in his Liushu benyi (六書本義, 1370s). The diagram is combined with the eight trigrams (bagua) and called the "River Chart spontaneously generated by Heaven and Earth". By the end of the Ming period, this diagram had become an widespread representation of Chinese cosmology.
Lai Zhide's design is similar to the gakyil (dga' 'khyil or "wheel of joy") symbols of Tibetan Buddhism; but while the Tibetan designs have three or four swirls (representing the Three Jewels or the Four Noble Truths, i.e. as a triskele and a tetraskele design), Lai Zhide's taijitu has two swirls, terminating in a central circle.
Modern yin-yang symbol
The Ming-era design of the taijitu of two interlocking spirals has been reported as "yin-yang symbol" in the first half of the 20th century. The flag of South Korea, originally introduced as the flag of Joseon era Korea in 1882, shows this symbol in red and blue. This was a modernisation of the older (early 19th century) form of the Bat Quai Do used as the Joseon royal standard.
Since the 1960s, "yin-yang symbol" is most widely applied to the He tu symbol which combines the two interlocking spirals with two dots. In the standard form of the contemporary "yin-yang symbol", one draws on the diameter of a circle two non-overlapping circles each of which has a diameter equal to the radius of the outer circle. One keeps the line that forms an "S," and one erases or obscures the other line. The design is also described[according to whom?][year needed] "pair of fishes nestling head to tail against each other".
The modern symbol has also been widely used in martial arts, particularly t'ai chi ch'uan (Taijiquan), and Jeet Kune Do, since the 1970s. In this context, it is generally used to represent the interplay between hard and soft techniques.
The dots in the modern "yin-yang symbol" have been given the additional interpretation of "intense interaction" between the complementary principles. 
The 1882 flag of Korea (since 1949 the flag of South Korea)
"Yin-Yang symbol or Tao symbol" (without the dots) as reported in 1964.
Comparison with prehistoric symbols
As discussed above, a modern form of the "yin yang symbol" is by no means representative of graphical representations of tajitu prior to the 19th century, but it has become widely recognizable, and the term is also used for unrelated designs dividing a circle by an "S"-shape. Such unrelated designs are widespread, and are found, for example, in artefacts of the European Neolithic. Such similarities have notably been used to illustrate a supposed "similarity of Tripilja culture and the culture of ancient China" in the Ukraine pavilion at the Expo 2010 in Shanghai, China. The "interlocking comma" design is also found in artefacts of the European Iron Age, popularly dubbed "Celtic yin-yang". While the design appears to become a standard ornamental motif in the La Tène culture by the 3rd century BC, found on a wide variety of artefacts, it is not clear what symbolic value, if any, was attached to it. Unlike the classic Taoist symbol, the "Celtic yin-yang" whorls consistently lack the element of mutual penetration, and the two halves are not always portrayed in different colors. Comparable designs are also found in Etruscan art.
- Joseph A. Adler, Reconstructing the Confucian Dao: Zhu Xi's Appropriation of Zhou Dunyi, SUNY Press, 2014, p. 153
- "The 'River Diagram' is the pattern of black-and-white dots which appears superimposed on the interlocking spirals [...] Those spirals alone form the Taiji tu or 'Diagram of the Supreme Ultimate', often known in English since the 1960s as the 'yin-yang symbol'.) These dots were believed to be collated with the eight trigrams, and hence with the concepts of roundness and of the heavens, while the equally numinous 'Luo River Writing' was a pattern of dots accosiated with the number nine, with squareness and with the earth." Craig Clunas, Pictures and Visuality in Early Modern China (1997), p. 107.
- Peyre 1982, pp. 62–64, 82 (pl. VI); Harding 2007, pp. 68f., 70f., 76, 79, 84, 121, 155, 232, 239, 241f., 248, 253, 259; Duval 1978, p. 282; Kilbride-Jones 1980, pp. 127 (fig. 34.1), 128; Laing 1979, p. 79; Verger 1996, p. 664; Laing 1997, p. 8; Mountain 1997, p. 1282; Leeds 2002, p. 38; Megaw 2005, p. 13
- Peyre 1982, pp. 62–64
- Monastra 2000; Nickel 1991, p. 146, fn. 5; White & Van Deusen 1995, pp. 12, 32; Robinet 2008, p. 934
- in the I Ching, originally a divination manual of the Western Zhou period (c. 1000–750 BC), yin and yang are represented by broken and solid lines: yin is broken (⚋) and yang is solid (⚊).
- Joseph A. Adler, Reconstructing the Confucian Dao: Zhu Xi's Appropriation of Zhou Dunyi, SUNY Press, 2014, p. 152
- Adler, Joseph A. (1999). "Zhou Dunyi: The Metaphysics and Practice of Sagehood", in Sources of Chinese Tradition, William Theodore De Bary and Irene Bloom, eds. 2nd ed., 2 vols. Columbia University Press. pp. 673–674.
- Xinzhong Yao (13 February 2000). An introduction to Confucianism. Cambridge University Press. pp. 98–. ISBN 978-0-521-64430-3. Retrieved 29 October 2011.
- François Louis, 'The Genesis of an Icon: The "Taiji" Diagram's Early History', Harvard Journal of Asiatic Studies 63.11 (June 2003), 145–196.
- Robert Beer, The Handbook of Tibetan Buddhist Symbols, 2003, p. 209
- Peyre 1982, pp. 62f.
- Robinet 2008, p. 934
- Davis, Barbara (2004). Taijiquan Classics. Berkeley, California: North Atlantic Books. p. 212. ISBN 978-1-55643-431-0.
- "Yin Yang symbol" (with dots) as part of "embroidered emblems", Martial Arts Shopping Guide (advertisement), Black Belt magazine, August 1974, p. 23.
- "the yin/yang symbol so familiar to us contains a white dot amid the black and a black dot amid the white to indicate that these principles interact intensely." Norman R. Kraft, Ogdoadic Magick, Weiser Books, 1969, p. 23.
- "The figures in the inner space are the dual forces, Yin and Yang, symbolized by darkness and light, which forms the starting point of Chinese philosophy" W.A.P. Martin, A cycle of Cathay, or, China, south and north (1897).
- Archie J. Bahm, The World's Living Religions, Jain Publishing Company, 1964, p. 156.
- More about Taiji Symbols of Ukraine Pavilion at Expo 2010 (xingyimax.com)[unreliable source?]
- Peyre 1982, pp. 62–64, 82 (pl. VI)
- beaked flagons, helmets, vases, bowls, collars, hand-pins, cross-slabs, brooches and knife blades. Harding 2007, pp. 70f., 76, 79, 155, 232, 241f., 248, 259; Kilbride-Jones 1980, p. 128
- "apotropaic": Duval 1978, p. 282
- Duval 1978, p. 282; Monastra 2000
- Robinet, Isabelle (2008), "Taiji tu. Diagram of the Great Ultimate", in Pregadio, Fabrizio, The Encyclopedia of Taoism A−Z, Abingdon: Routledge, pp. 934–936, ISBN 978-0-7007-1200-7
- Duval, Paul-Marie (1978), Die Kelten, München: C. H. Beck, ISBN 3-406-03025-4
- Harding, D. W. (2007), The Archaeology of Celtic Art, Routledge, ISBN 0-203-69853-3
- Kilbride-Jones, H. E. (1980), Celtic Craftsmanship in Bronze, Taylor & Francis, ISBN 0-7099-0387-1
- Laing, Lloyd (1979), Celtic Britain, Routledge & Kegan Paul Ltd, ISBN 0-7100-0131-2
- Laing, Lloyd (1997), Later Celtic Art in Britain and Ireland, Shire Publications LTD, ISBN 0-85263-874-4
- Megaw, Ruth and Vicent (2005), Early Celtic Art in Britain and Ireland, Shire Publications LTD, ISBN 0-7478-0613-6
- Monastra, Giovanni (2000), "The "Yin-Yang" among the Insignia of the Roman Empire?", Sophia 6 (2)
- Mountain, Harry (1997), The Celtic Encyclopedia 5, ISBN 1-58112-894-0
- Nickel, Helmut (1991), "The Dragon and the Pearl", Metropolitan Museum Journal 26: 139–146, doi:10.2307/1512907
- Peyre, Christian (1982), "Y a-t’il un contexte italique au style de Waldalgesheim?", in Duval, Paul-Marie; Kruta, Venceslas, L’art celtique de la période d’expansion, IVe et IIIe siècles avant notre ère, Hautes études du monde gréco-romain 13, Paris: Librairie Droz, pp. 51–82 (62–64, 82), ISBN 978-2-600-03342-8
- Verger, Stéphane (1996), "Une tombe à char oubliée dans l'ancienne collection Poinchy de Richebourg", Mélanges de l'école française de Rome 108 (2), pp. 641–691
- White, Lynn; Van Deusen, Nancy Elizabeth (1995), The Medieval West Meets the Rest of the World, Claremont Cultural Studies 62, Institute of Mediaeval Music, ISBN 0-931902-94-0
Media related to Yin Yang at Wikimedia Commons
- Where does the Chinese Yin Yang Symbol Come From? (chinesefortunecalendar.com)
- Chart of the Great Ultimate (Taiji tu) (goldenelixir.com)