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Taoism
This article is part of a series on Taoism
Fundamentals
Dao (Tao) · De (Te) · Wuji · Taiji · Yin-Yang · Wu xing · Qi · Neidan · Wu wei
Texts
Laozi (Tao Te Ching) · Zhuangzi · Liezi · Daozang
Deities
Three Pure Ones · Yu Huang · Guan Shengdi · Eight Immortals · Yellow Emperor · Xiwangmu · Jade Emperor · Chang'e · Other deities
People
Laozi · Zhuangzi · Zhang Daoling · Zhang Jiao · Ge Hong · Chen Tuan
Schools
Tianshi Dao · Shangqing · Lingbao · Quanzhen Dao · Zhengyi Dao · Wuliupai
Sacred sites
Grotto-heavens · Mount Penglai
Taoism Portal  v • d • e

In Chinese philosophy, the concept of yin yang ([yin – simplified Chinese: 阴; traditional Chinese: 陰; pinyin: yīn] [yang - simplified Chinese: 阳; traditional Chinese: 陽; pinyin: yáng] often referred to in the west as yin and yang) is used to describe how polar or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn. The concept lies at the heart of many branches of classical Chinese science and philosophy, as well as being a primary guideline of traditional Chinese medicine,^[1] and a central principle of different forms of Chinese martial arts and exercise, such as baguazhang, taijiquan, and qigong and of I Ching divination. Many natural dualities — e.g. dark and light, female and male, low and high, cold and hot — are viewed in Chinese thought as manifestations of yin and yang.
Yin yang are complementary opposites within a greater whole. Everything has both yin and yang aspects, although yin or yang elements may manifest more strongly in different objects or at different times. Yin yang constantly interacts, never existing in absolute stasis. The concept of yin and yang is often symbolized by various forms of the Taijitu symbol, for which it is probably best known in western cultures.
There is a common misperception (especially in the West) that yin and yang correspond to good and evil. However, Taoist philosophy generally discounts good/bad distinctions as superficial labels, preferring to focus on the idea of balance. The idea that yin and yang has a moral dimension originated in the Confucian school (most notably Dong Zhongshu) around the second century BCE^[2].

The nature of yin–yang

In Taoist philosophy, yin and yang arise together from an initial quiescence or emptiness (wuji, sometimes symbolized by an empty circle), and continue moving in tandem until quiescence is reached again. For instance, dropping a stone in a calm pool of water will simultaneously raise waves and lower troughs between them, and this alternation of high and low points in the water will radiate outward until the movement dissipates and the pool is calm once more. Yin–yang, thus, are always opposite and equal qualities. Further, whenever one quality reaches its peak it will naturally begin to transform into the opposite quality: grain that reaches its full height in summer (fully yang) will produce seeds and die back in winter (fully yin) in an endless cycle.
It is impossible to talk about yin or yang without some reference to the opposite, since yin–yang are bound together as parts of a mutual whole. A race with only men or only women would disappear in a single generation; but men and women together create new generations that allow the race they mutually create (and mutually come from) to survive. The interaction of the two gives birth to things.^[3] Yin and yang transform each other: like an undertow in the ocean, every advance is complemented by a retreat, and every rise transforms into a fall. Thus, a seed will sprout from the earth and grow upwards towards the sky – an intrinsically yang movement. Then when it reaches its full potential height it will fall.

"Yang" and "Yin" in place names

Many places in China, such as Luoyang, contain the word "Yang", and a few, such as Huayin, the word "yin". This is a very old way to assign place names. "Yang" means that a place is on the south slope of a mountain or on the north side of a river - for example, Luoyang is on the north side of the Luo River. "Yin" means that a place is on the north slope of a mountain or on the south side of a river - for example, Huayin is on the north slope of Mount Hua.

Symbolism and its importance

The relationship between yin and yang is often described in terms of sunlight playing over a mountain and in the valley. Yin (literally the 'shady place' or 'north slope') is the dark area occluded by the mountain's bulk, while yang (literally the 'sunny place' or 'south slope') is the brightly lit portion. As the sun moves across the sky, yin and yang gradually trade places with each other, revealing what was obscured and obscuring what was revealed.
Yin is usually characterized as slow, soft, insubstantial, diffuse, cold, wet, and tranquil. They are generally associated with Femininity, birth and generation, and with the Night.
Yang, by contrast, is characterized as fast, hard, solid, dry, focused, hot, and aggressive. They are associated with Masculinity and with the Daytime.^[4]

I Ching

In the I Ching, yin yang are represented by broken and solid lines: yang is solid (⚊) and yin is broken (⚋). These are then combined into trigrams, which are more yang or more yin depending on the number of broken and solid lines (e.g., ☰ is heavily yang, while ☷ is heavily yin), and trigrams are combined into hexagrams (e.g. ䷕ and ䷟). The relative positions and numbers of yin and yang lines within the trigrams determines the meaning of that trigram, and in hexagrams the upper trigram is considered yang with respect to the lower trigram, allowing complex depictions of interrelations.

Taijitu

The principle of yin and yang is represented in Taoism by the Taijitu (literally "diagram of the supreme ultimate") diagram. The term is commonly used to mean the simple 'divided circle' form, but may refer to any of several schematic diagrams representing these principles. Similar symbols have also appeared in other cultures, such as in Celtic art and Roman shield markings.^[5][6][7]

Taijiquan

Taijiquan, a form of martial art, is often described as the principles of yin and yang applied to the human body. Wu Jianquan, a famous Chinese martial arts teacher, described Taijiquan as follows:

Various people have offered different explanations for the name Taijiquan. Some have said: – 'In terms of self-cultivation, one must train from a state of movement towards a state of stillness. Taiji comes about through the balance of yin and yang. In terms of the art of attack and defense then, in the context of the changes of full and empty, one is constantly internally latent, not outwardly expressive, as if the yin and yang of Taiji have not yet divided apart.' Others say: 'Every movement of Taijiquan is based on circles, just like the shape of a Taijitu. Therefore, it is called Taijiquan.

– Wu Jianquan, The International Magazine of T’ai Chi Ch’uan^[8]

Religious and Philosophical

The yin-yang symbol and concept of the Zhou period reach into family and gender relations. Yin is female and yang is male. They fit together as two parts of a whole.
From a philosophical standpoint practitioners of Zen Yoga see yin-yang as a flow.

The Yin/Yang symbol is one of the oldest and best-known life symbols in the world, but few understand its full meaning. It represents one of the most fundamental and profound theories of ancient Taoist philosophy. At its heart are the two poles of existence, which are opposite but complementary. The light, white Yang moving up blends into the dark, black Yin moving down. Yin and Yang are dependent opposing forces that flow in a natural cycle, always seeking balance. Though they are opposing, they are not in opposition to one another. As part of the Tao, they are merely two aspects of a single reality. Each contains the seed of the other, which is why we see a black spot of Yin in the white Yang and vice versa. They do not merely replace each other but actually become each other through the constant flow of the universe. ^[9]