The eight trigrams, each representing a compass point, surround the yin–yang symbol.

Yin–yang theory, embodying the most basic forces in nature, is an important component of Chinese philosophy, medicine, divination, and feng shui. It unites the Confucian emphasis on virtue with the Daoist emphasis on harmony with nature.

Yin–yang theory, originally referring to the shady and sunny parts of gorges and mountains, is integral to Chinese philosophy, medicine, divination, and geomancy (feng shui). The term came to embody the most basic forces in nature, such as male/female, night/day, and old/young.

First used in the fourteenth century BCE, yin–yang theory was able to unite the Confucian focus on virtue and the Daoist concern for living in harmony with nature within its naturalistic philosophy. The character yin referred to the shady, northern side of a mountain or the southern side of a gorge, and yang to the sunny, southern side of a mountain or the northern side of a gorge.

By the Spring and Autumn period (770–476 BCE) yin and yang were beginning to take on cosmological significance as two of the six forms of material force (qi), namely, shady-yin, sunny-yang, wind, rain, dark, and light. It was believed that success/health and disaster/illnesses are related to an excess or deficiency of shady-yin and sunny-yang. During the Warring States period (475–221 BCE) yin and yang began to take on a more encompassing philosophical meaning as the most basic forces and, by extension, the most general categories for classifying all things in existence. The concepts yin and yang are used as philosophical categories in the naturalistic philosophies of the Daoist texts Laozi and Zhuangzi and the Confucian book Xunzi. As philosophical categories yin and yang are understood to be two opposing yet interconnected forces; they are not a duality. Yin contains yang, and yang contains yin. When one extreme is exhausted the other force comes into play. They are similar to the negative and positive charges in the electro-magnetic spectrum. The following list depicts some of the major correlations associated with them:

Earth Heaven
Autumn Spring
Night Day
Small states Large states
Rest Action
Below Above
Younger Elder
Female Male

Zou Yan (c. 305–240 BCE) was the founder of the yin–yang five-phases school. He associated yin and yang with the five phases (wuxing), namely, wood, fire, earth, metal, and water, creating a more dynamic explanation for the processes of change. Wood and fire are associated with yang; metal, earth, and water are yin. The five phases first appeared in the “Grand Norm” chapter of the Classic of Documents, a book comprising fifty-eight chapters with documents and records relating to the ancient history of China. Rubin argues that Zou Yan transformed the static categories of the five phases into a dynamic and temporal system by connecting it to the undulating pulsations of yin and yang. Scholars debate whether Zou and his school should be classified as a naturalist philosophy or as diviners and geomancers. The yin–yang philosophy is closely related to both natural philosophy and divination because by being aware of the natural processes of change a person is in a better position to predict the future. The Annals of Lü Buwei (c. 240 BCE) contains the following passage that describes the application of the five phases theory in political philosophy.

When ever an emperor or king is about to arise, Heaven is certain to manifest good omens to the people below. At the time of the Yellow Emperor, Heaven first caused giant mole crickets and earthworms to appear. The Yellow Emperor announced, “The ethers of Earth are in ascendance.” Since the ethers of Earth were ascendant, he honored the color yellow and modeled his activities on Earth. When it came to the time of Yu, Heaven first caused trees and grasses to appear that did not wither in autumn and winter. Yu Proclaimed, “The ethers of Wood are in ascendance.” Since the ethers of Wood were ascendant, he honored the color green and modeled his affairs on Wood. When it came to the time of Tang, Heaven first caused metal blades to appear coming froth from Water. Tang proclaimed, “The ethers of Metal are in ascendance.” Since the ethers of Metal were ascendant, he honored the color white and modeled his affairs on Metal. When it came to the time of King Wen, Heaven first caused a fiery-red crow to appear and alight on the altars of Zhou, holding in its beak a document written in cinnabar. King Wen proclaimed, “The ethers of Fire are in ascendance.” Since the ethers of Fire were ascendant, he honored the color vermilion and modeled his affairs on Fire. (modifying Knoblock & Riegel 2000, 283)

The preceding passage depicts the rise and fall of dynasties according to the conquest cycle of the five phases, in which water extinguishes fire, fire melts metal, metal cuts wood, wood breaks up earth, and earth obstructs water. A ruler could influence state affairs with this model by advocating that his form of government was aligned with the cosmic forces. For example, the state of Qin vanquished the house of Zhou in 256 BCE, but not until the unification of the empire, in 221 BCE, did the first emperor of Qin adopt the color black and model his affairs on water. He justified his rule by adopting the five phases theory. During the Han dynasty (206 BCE–220 CE) court officials continued to debate which one of the five phases was ascending and what color and emblem the state should institute as its model. If the natural cycles of yin, yang, and the five phases could be used to determine the rise and fall of states, then they should have application to all sorts of endeavors. During the Han dynasty yin–yang theory was used to explain natural phenomena, human activities, health, and wealth.

Besides the conquest cycle for the five phases, there is a cycle of generation in which earth grows wood, wood fuels fire, fire’s ash produces earth, earth produces metal, and metal precipitates water. During the early Han dynasty (206 BCE–220 CE) the yin–yang and five phases were expanded into a comprehensive classification system such that everything was classified as being predominantly yin or yang and further linked to one of the five phases. This comprehensive approach paved the way for yin–yang theory to influence the practice of traditional Chinese medicine, divination, and geomancy. For example, the following chart links the phases to the five colors, directions, seasons, internal organs, and numbers.

The Five Phases


Green Red Yellow White Black
East South Center West North
Spring Summer Late Summer Autumn Winter
Liver Spleen Lungs Kidneys
Eight Seven Five Nine Six

Each of the five phases also correlates with any number of natural phenomena. By understanding the relationships between the five phases and other natural phenomena and whether or not the generation or destruction cycle is at work, a person can predict what phenomena will arise next. The alleged diagnostic and predictive powers of the yin–yang five phases theory naturally influenced the practice of Chinese medicine and divination.


Traditional Chinese medicine pays close attention to environmental influences on people’s health. It has always been concerned about the influences of cold/heat, damp/dry climate, and light/dark on a person’s health. By the beginning of the Han dynasty when yin–yang theory was taking shape, traditional Chinese medicine was being formalized. Yin–yang theory’s influence on traditional Chinese medicine is seen in the early medical texts, namely, The Spiritual Pivot and The Yellow Emperor’s Classic of Internal Medicine. All health-related phenomena are associated with yin, yang, and the five phases. At conception each individual is bestowed an allotment of prenatal-energy qi, composed of yin and yang. When yin, yang, and the five phases operate in harmony there is health. Illness develops when they are imbalanced. The physiology, pathology, diagnosis, and treatment of illness in Chinese medicine are described in terms of yin–yang theory. All symptoms and physiological processes are analyzed according to the yin–yang five phases theory. There are basically four treatment modalities: to tonify yin or yang and to eliminate excess yin or yang. Chinese medicine employs the dynamic transformations of yin and yang in accounting for the processes of health and illness. As opposites yin and yang are interdependent, contain each other, and mutually consume each other. Bodily parts and structures are assigned yin–yang associations. Yin is associated with structure and yang with function. The lower extremities, interior, and front are yin. The upper extremities, exterior, and back are yang. So all of the yang channels flow through the back and begin or end at the head. The yin channels flow through the abdomen and chest and begin or end below the waist. Likewise, pathogenic factors follow the yin–yang pattern. So the upper body is affected by yang factors such as wind and summer heat. The lower body is affected by dampness and cold.

Bodily organs are also classified according to yin and yang. The yin organs store energy; the yang organs digest and excrete food to generate energy. Through the bodily openings the yang organs such as the stomach, intestines, and bladder are in contact with the exterior. Like the yang force, the yang organs are active constantly filling, emptying, and digesting food. The yin organs are tranquil and store the energy and vital substances, such as qi, blood, and other bodily fluids within the body. Because yin and yang are never separated, all organs have them. Yin correlates to an organ’s structure and yang to its function. Like yin and yang, structure and function are interconnected and codependent. For example, the spleen’s yang function is to transform food into blood, which is the yin structure of the spleen. Blood-and-energy qi form a bipolar relationship: Blood nourishes and moistens, like yin; energy qi is warming, protecting, and transforming, like yang. Defensive and nutritive energy follow the paradigm. Defensive energy circulates in the skin and muscles and is yang. Nutritive energy is yin, circulating in the internal organs.

Yin–yang theory forms the basic character of all symptoms and signs in Chinese medicine. The basic qualities that direct clinical practice are assigned the following correlations:

Water Fire
Cold Hot
Quiet Restless
Wet Dry
Soft Hard
Inhibited Excited
Slow Rapid

Water is associated with the kidneys; fire with the heart. Maintaining a balance between water and fire is most important for health. Water moistens and nourishes the body; fire heats the body and fuels the metabolic processes. Fire in the heart helps maintain emotional well-being. Its warming energy allows the spleen to produce blood, facilitating the small intestine’s digestion and the bladder’s ability to excrete fluids. The major clinical manifestations correlate as follows:

Chronic disease Acute disease
Gradual onset Rapid onset
Lingering disease Rapid changes
Cold Hot
Sleepy Insomnia
Likes bed covers Throws off covers
Curls up Lies stretched out
Pale face Red face
Prefers hot drinks Prefers cold drinks
Weak voice Loud voice
Shallow breathing Coarse breathing
No thirst Thirst
Profuse, pale urine Scanty, dark urine
Loose stools Constipated
Pale tongue Red tongue
Empty pulse Full pulse

Yin–yang theory forms the foundation for an understanding of the clinical manifestations of symptoms. The yin–yang correlations must be integrated with the eight principles and the theory of internal organ patterns to be used successfully in diagnosing illnesses.


Divination has always played a role in Chinese culture. In the Shang dynasty (1766–1045 BCE) oracle bones were employed for this purpose. The bones were prepared and heated, and when the bone cracked, the lines were “read” for divination. The I Ching (Yijing, Classic of Changes), the Confucian text of divination, is dated to the early Zhou dynasty (1045–256 BCE). Although the terms yin and yang to do not appear within the main body of the Classic of Changes, the text has been interpreted according to those categories. The appendix to the Changes defines the dao as one yin and one yang. The method of divination developed in the Changes is based on symbolic images depicted by solid and broken lines. The broken line is associated with yin and the solid line with yang. The following figures depict the progression.

The first chapter of the Changes is “Qian,” represented by three solid lines arranged vertically. It is associated with pure yang, heaven, and light. The second chapter of the Changes is “Kun,” represented by three broken lines. Kun is associated with pure yin, earth, and darkness. There are eight different possible permutations combining solid and broken lines. These are known as the “Eight Trigrams” (Bagua). They are combined into the sixty-four hexagrams that comprise the chapters of the Changes. The Eight Trigrams are typically arranged around the eight compass points, giving them a spatial orientation. The trigrams especially represent temporal changes and are correlated with the seasons, the phases of the moon, the days of the week, and the hours of the day. The traditional Chinese calendar is a hybrid of both lunar and solar calendars. The four seasons are subdivided into three moons or months consisting of three ten-day weeks.
The day is divided into twelve two-hour periods. Yin and yang are associated with the year, month, week, day, and hour. These time periods are also associated with a hexagram. The time of day or the day of the week can be used to find a hexagram to determine whether that time is auspicious or not. Because yin–yang theory and the principles of divination both focus on the process of change, it is natural that the two systems merged together.

Feng Shui: The Art of Placement

Feng shui literally means “wind and water.” It is the ancient art, science, and magic of geomancy. It is employed in both ancient and modern architecture. Because wind and water are two of the most powerful natural forces that shape the landscape and pose a threat to human habitation, the art of living in harmony with the forces of nature came to be referred to as feng shui. Until recently feng shui was dismissed as mere superstition and an appeal to magic. In part feng shui practices are concerned with promoting good luck and avoiding bad luck, but they also have a practical and an aesthetic aspect. Some feng shui practices have artistic appeal and are based on sound observations. Feng shui is the art of placement that promotes both aesthetic and ecological values. Modern people recognize the aesthetic value of feng shui practices, especially in arranging a Chinese-, Korean-, or Japanese-style garden. Feng shui practices promote building homes and other structures in such a manner that they take advantage of the natural surrounding, allowing natural light and heat to enter the building in the winter and cool breezes in the summer. The aesthetic and ecological advantages of feng shui have revitalized people’s interest in it.

Yin–yang theory plays an important role in the ancient art of placement. Any human structure, whether it is a farm, a garden, a building, a home, or a grave, will impose itself on the natural surrounding. It will have to withstand the forces of nature and adjust to the changes of the seasons and climate, so it will have to be in harmony with those forces, which are governed by yin and yang. Daoist priests are traditionally the master practitioners of feng shui. They use a loban, or feng shui compass. The compass has a magnetic north-south needle in the center, which is surrounded by concentric circles containing other information such as the seventy-two dragon veins, the twenty-eight constellations, the 360 degrees of the compass, the sixty points of good and bad luck, the eight trigrams, the auspicious river directions, and good and bad burial positions. The eight major compass points are associated with the eight treasures as follows: Fame is associated with the south; wealth with the southeast; education with the east; children with the northeast; relationships with the north; friends with the northwest; pleasure with the west; and health with the southwest. The direction the front door of a person’s home faces will determine which one of the eight treasures is most benefited in that person’s life. For example, if someone seeks to improve her relationships, then she should move into a house with a front door that faces north, so that her comings and goings take her through the relationship area. Because feng shui assists people in determining the aesthetic and practical value of the art of placing objects in the home and within the natural environment, feng shui continues to inspire architects and common people.

Yin–yang theory has its roots in ancient political philosophy. Through the syncretic approach of Han dynasty philosophy, the yin–yang five phases theory was integrated into other aspects of natural philosophy, medicine, divination, and the art of placement.

Further Reading

Craze, R. (1997). Practical feng shui: The Chinese art of living in harmony with your surroundings. New York: Lorenz Books.

Graham, A. C. (1986). Yin-yang and the nature of correlative thinking. Occasional paper and monograph series, 6. Singapore: Institute of East Asian Philosophies.

Graham, A. C. (1989). Disputers of the Tao. La Salle, IL: Open Court.

Jarrett, L. S. (1998). Nourishing destiny: The inner tradition of Chinese medicine. Stockbridge, MA: Spirit Path Press.

Knoblock, J., & Riegel, J. (2000). The annals of Lü Buwei. Stanford, CA: Stanford University Press.

Maciocia, G. (1989). The foundations of Chinese medicine: A comprehensive text for acupuncturists and herbalists. New York: Churchill Livingstone.

Rubin, V. A. (1982). The concepts of wu-hsing and yin-yang. Journal of Chinese Philosophy, 9(2), 131–158.

Wilhelm, R. (1978). The I ching (C. F. Baynes, Trans.). Princeton, NJ: Princeton University Press.

Source: Sellmann, James D.. (2009). Yin–Yang Theory. In Linsun Cheng, et al. (Eds.), Berkshire Encyclopedia of China, pp. 2580–2584. Great Barrington, MA: Berkshire Publishing.

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