Yin and yang

Originating in ancient Chinese philosophy, yin and yang or yin-yang is the concept that there exist cosmic principles or forces that are opposite but complementary, which interact, interconnect, support and perpetuate each other. Together they form a dynamic system in which the whole is greater than the interdependent components, and both parts are essential for the cohesion of the whole.
In Chinese mythology, the universe develops out of a primary chaos of primordial qi or material energy, organized into the cycles of yin and yang, force and motion leading to form and matter. "Yin" is retractive, passive, contractive and receptive in nature in a contrasting relationship to "yang" that is repelling, active, expansive and repulsive in principle; this dichotomy in some form, is seen in all things in nature and their patterns of change, difference and transformations. For example, biological, psychological and cosmological seasonal cycles, the historical evolution of landscapes over days, weeks, years to eons. The original meaning of yin was depicted as the northerly shaded side of a hill and yang being the bright southerly aspect. When pertaining to human gender, yin is associated to more rounded feminine characteristics and yang as sharp and masculine traits.
Taiji is a Chinese cosmological term for the "Supreme Ultimate" state of undifferentiated absolute and infinite potential, the oneness before duality, from which yin and yang originate. It can be contrasted with the older wuji. In the cosmology pertaining to yin and yang, the material energy which this universe was created from is known as qi. It is believed that the organization of qi in this cosmology of yin and yang is the formation of the 10 thousand things between Heaven and Earth.
Included among these forms are humans. Many natural dualities are thought of as physical manifestations of the duality symbolized by yin and yang. This duality, as a unity of opposites, lies at the origins of many branches of classical Chinese science, technology and philosophy, as well as being a primary guideline of traditional Chinese medicine, and a central principle of different forms of Chinese martial arts and exercise, such as baguazhang, tai chi, daoyin, kung fu and qigong, as well as appearing in the pages of the I Ching and the famous Taoist medical treatise called the Huangdi Neijing.
In Taoist metaphysics, distinctions between good and bad, along with other dichotomous moral judgments, are perceptual, not real; so, the duality of yin and yang is an indivisible whole. In the ethics of Confucianism on the other hand, most notably in the philosophy of Dong Zhongshu, a moral dimension is attached to the idea of yin and yang. The Ahom philosophy of duality of the individual self han and pu is based on the concept of the hun 魂 and po 魄 that are the yin and yang of the mind in the philosophy of Taoism. The tradition was originated in Yunnan, China and followed by some Ahom, descendants of the Dai ethnic minority.

Linguistic aspects

Characters

The Chinese characters and are both phono-semantic compounds, with semantic component 'mound', 'hill', a graphical variant of —with the phonetic components and. In the latter, features + +.

Pronunciations and etymologies

The Standard Chinese pronunciation of is usually the level first tone as with the meaning, or sometimes with the falling fourth tone as with the distinct meaning. is always pronounced with the rising second tone as.
Sinologists and historical linguists have reconstructed Middle Chinese pronunciations from data in the Qieyun rhyme dictionary and later rhyme tables, which was subsequently used to reconstruct Old Chinese phonology from rhymes in the 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 reconstructions of and :

< and <
* and
and
< and <
< and <

Schuessler gives probable Sino-Tibetan etymologies for both Chinese words.
< compares with Burmese 'overcast', 'cloudy', Adi 'shade', and Lepcha 'shade'; it is probably cognate with Chinese < and < .
< compares with Lepcha a-lóŋ 'reflecting light', Burmese laŋ^B 'be bright' and ə-laŋ^B 'light'; and is perhaps cognate with Chinese < . To this word-family, Unger also includes < 'bright'; however Schuessler reconstructs 's Old Chinese pronunciation as and includes it in an Austroasiatic word family, besides < < 'twilight of dawn'; < 'bright', 'become light', 'enlighten'; owing to "the different OC initial consonant which seems to have no recognizable OC morphological function".

Meanings

Yin and yang are semantically complex words.
John DeFrancis's ABC Chinese-English Comprehensive Dictionary gives the following translation equivalents.

Yin or —Noun: ① female/passive/negative principle in nature, ② Surname; Bound morpheme: ① the moon, ② shaded orientation, ③ covert; concealed; hidden, ④ vagina, ⑤ penis, ⑥ of the netherworld, ⑦ negative, ⑧ north side of a hill, ⑨ south bank of a river, ⑩ reverse side of a stele, ⑪ in intaglio; Stative verb: ① overcast, ② sinister; treacherous

Yang or —Bound morpheme: ① male/active/positive principle in nature, ② the sun, ③ male genitals, ④ in relief, ⑤ open; overt, ⑥ belonging to this world, ⑦ masculine, ⑧ south side of a hill, ⑨ north bank of a river

The compound yinyang 陰陽 means "yin and yang; opposites; ancient Chinese astronomy; occult arts; astrologer; geomancer; etc."
The sinologist Rolf Stein glosses Chinese yin 陰 as "shady side " and yang 陽 as "sunny side " with the uncommon English geographic terms ubac "shady side of a mountain" and adret "sunny side of a mountain".

Toponymy

Many Chinese place names or toponyms contain the word yang 'sunny side', and a few contain yin 'shady side'. In China, as elsewhere in the Northern Hemisphere, sunlight comes predominantly from the south, and thus the south face of a mountain or the north bank of a river will receive more direct sunlight than the opposite side. For example, Yang refers to the "south side of a hill" in Hengyang 衡陽, which is south of Mount Heng 衡山 in Hunan, and to the "north bank of a river" in Luoyang 洛陽, which is located north of the Luo River 洛河 in Henan. Similarly, yin refers to "north side of a hill" in Huayin 華陰, which is north of Mount Hua 華山 in Shaanxi province.
In Japan, the characters are used in western Honshu to delineate the north-side San'in region 山陰 from the south-side San'yō region 山陽, separated by the Chūgoku Mountains 中国山地.

Loanwords

English yin, yang, and yin-yang are familiar loanwords of Chinese origin.
The Oxford English Dictionary defines:

yin Also Yin, Yn. [Chinese yīn shade, feminine; the moon.]
a. In Chinese philosophy, the feminine or negative principle of the two opposing cosmic forces into which creative energy divides and whose fusion in physical matter brings the phenomenal world into being. Also attrib. or as adj., and transf. Cf. yang.
b. Comb., as yin-yang, the combination or fusion of the two cosmic forces; freq. attrib., esp. as yin-yang symbol, a circle divided by an S-shaped line into a dark and a light segment, representing respectively yin and yang, each containing a 'seed' of the other.

yang Also Yang. [Chinese yáng yang, sun, positive, male genitals.]
a. In Chinese philosophy, the masculine or positive principle of the two opposing cosmic forces into which creative energy divides and whose fusion in physical matter brings the phenomenal world into being. Also attrib. or as adj. Cf. yin.
b. Comb.: yang-yin = yin-yang s.v. yin b.

For the earliest recorded "yin and yang" usages, the OED cites 1671 for yin and yang, 1850 for yin-yang, and 1959 for yang-yin.
In English, yang-yin occasionally occurs as a mistake or typographical error for the Chinese loanword yin-yang—yet they are not equivalents. Chinese does have some yangyin collocations, such as 洋銀 "silver coin/dollar", but not even the most comprehensive dictionaries enter yangyin *陽陰. While yang and yin can occur together in context, yangyin is not synonymous with yinyang. The linguistic term "irreversible binomial" refers to a collocation of two words A–B that cannot be idiomatically reversed as B–A, for example, English cat and mouse and friend or foe.
Similarly, the usual pattern among Chinese binomial compounds is for positive A and negative B, where the A word is dominant or privileged over B. For example, tiandi 天地 "heaven and earth" and nannü 男女 "men and women". Yinyang meaning "dark and light; female and male; moon and sun", is an exception. Scholars have proposed various explanations for why yinyang violates this pattern, including "linguistic convenience", the idea that "proto-Chinese society was matriarchal", or perhaps, since yinyang first became prominent during the late Warring States period, this term was "purposely directed at challenging persistent cultural assumptions".

History

discusses yin and yang together with Five Elements as part of the School of Naturalists. He says that it would be proper to begin with yin and yang before Five Elements because the former: "lay, as it were, at a deeper level in Nature, and were the most ultimate principles of which the ancient Chinese could conceive. But it so happens that we know a good deal more about the historical origin of the Five-Element theory than about that of the yin and the yang, and it will therefore be more convenient to deal with it first."
He then discusses Zou Yan who is most associated with these theories. Although yin and yang are not mentioned in any of the surviving documents of Zou Yan, his school was known as the Yin Yang Jia. Needham concludes "There can be very little doubt that the philosophical use of the terms began about the beginning of the 4th century, and that the passages in older texts which mention this use are interpolations made later than that time."