Yin and Yang Theory

NB: It is one of the best English descriptions of the Yang Yin theory we ever found

Taoism is a theory of the equilibrium of all nature. Based on early animism (doctrine of anima mundi; attribution of living soul to plants, inanimate objects and natural phenomena) and formalized in approximately 500 B.C. by the writings of Lao Tzu (Old Sage), and subsequently by those of Zhuang Zi (Chuang-Tzu), Taoism envisages a world in which the ideal condition is harmony - a perfect balance between human beings and the environment, and among human beings themselves. Taoism emphasizes relationships between opposites, aiming toward the perfection of equilibrium. The equilibrium itself is never permanent. Life is an ongoing process of give and take, of energy absorption and energy loss. As a consequence, every living process in nature is characterized by conflict, accommodation, and complementarities.
Today we call this homeostasis.

The fundamental forces of the Taoist world are named Yin and Yang. Yin means "in the shade;" Yang translates as "in the sunlight." Extrapolating from this basic concept Yin and Yang came to mean, respectively, darkness (Yin) and light (Yang), moon and sun, passivity and activity, female and male, cold and heat, inside and outside, down and up, left and right, negative and positive, substance and function, emptiness and fullness, hidden and exposed.

Just as the natural world is characterized by the antagonism and flow of Yin and Yang, so is the human body. Indeed, Taoism would find no reason to differentiate between the natural world and that of human experience. To the Taoist, dualism was the greatest error. Instead, Taoist philosophy suggests that we are an integral part of the whole, a flux and flow of vital energy within a larger energy.
Today we would call this holism.

Thus, when the authors of Huangdi's Internal Classic set out to study human physiology, they based their concept of health on the equilibrium of Yin and Yang. In chapter 5of the Su Wen (Plain Questions) they wrote: "Yin and Yang are the law of Heaven and Earth, the outline of everything, the parents of change, the origin of birth and destruction." The active and dynamic processes of the human body-such as eating, digesting, and metabolizing-they called Yang.

The passive functions - such as breathing and blood circulation - are seen as Yin. Diseases were also differentiated between Yin and Yang. Diseases that affect the bodily functions, are virulent in nature, and progress rapidly within the body or ascend from the viscera-to the head are considered to be Yang. Those that are organic, lie dormant, are degenerative, are characterized by low activity, or descend from the upper part of the body are Yin. The herbs taken to cure these diseases are, in their turn, also differentiated between Yin and Yang.

Yin and Yang in human health, as in all of nature, are both interdependent and mutually restricting. They rely on each other for their own being. Each contains within it the seed of the other. Where one increases the other decreases; when one reaches its peak the other emerges. These concepts are expressed in pictorial form by the well-known symbol of Yin and Yang's circular complementarity.

The symbol of Yang and Yin. The upper function, Yang, is in the light and is therefore white. The lower function, Yin, represents the shade and darkness. Yet as symbolized by the dots within each form, Yang and Yin each contain within itself the seed of its opposites; each is born from the other. When one increase the other increase..

The Yin and Yang aspects within a living body are in constant interaction, and one always increases at the expense of the other. Activity is Yang; nutrient substances are, in general, Yin. Thus any activity running, walking, talking-that consumes energy from digested nutrients lessens Yin and, as a result, increases Yang. On the other hand, the metabolism of those same nutrient substances (Yin) depletes the functional energy (Yang) and consequently increases Yin at the expense of Yang. In ordinary circumstances the mutual depletion and increase of Yin and Yang balances itself out. Unusual circumstances - too much activity, too much food, impaired metabolism, or too little activity or food create an imbalance. In the long term, the imbalance can lead to disease.

Yet Yin and Yang do not exert their influence purely as vital functions. They are, according to Chinese medical theory, attributes of parts of the body as well. Yang is above and Yin is below, therefore the top half of the human body is considered to be Yang and everything below the waist is Yin. Yang is outward and Yin inward. The inside of our body is Yin and the outside Yang. Similarly, the back is Yang and the front Yin, the sides are Yang and the central portion is Yin.

What is true of the body as a whole is also considered valid for the vital organs. In Chinese traditional medicine theory the vital organs are divided, according to their functions, into Zang (generating and storing organs) and fu (transforming, transporting, and distributing organs).

Generating and storing is considered a Yin activity, therefore the five Zang organs (wu Zang) - the heart, the liver, the spleen, the lungs, and the kidneys-are all considered Yin. Transforming, transporting, and distributing are said to be Yang activities. It follows, therefore, that the six fu organs (liu fu) - the gall bladder, the stomach, the small intestine, the large intestine, the urinary bladder, and the three main body cavities (san jiao)-are considered Yang.

Because Yin and Yang are everywhere complementary and interdependent, the parts of the human body that are Yang also contain aspects of Yin within themselves, and vice versa. What this means is that within the heart there exists a Yang function too: pumping blood through the body. Yet even within that Yang function of pumping lies a passive Yin function: blood circulation. Within that Yin of circulation can be found the Yang of nutrition to the vital organs. The organs themselves are Yin, which takes us back to where we started from: the heart.

The point is that Yang and Yin are interdependent and complementary to one another. They cannot exist in isolation. Each contains the seed and essence of the other. Within Yang there is Yin, within that Yin another Yang, and so on and so on to infinity.

As the Plain Questions of Huangdi's Internal Classic puts it: "In any one function, Yin and Yang could amount to ten in number, be extended to one hundred, to one thousand, to ten thousand and even to the infinite."

All healthy activities of the human body arise from the maintenance of this dynamic equilibrium between Yin and Yang. For example, when the lungs expand and contract they are performing a Yang action, as all breathing activity is Yang. The activity of breathing is based on the substance of the lungs-substance which is Yin. Therefore the Yang and the Yin of breathing are interdependent. When one is healthy, the other flourishes; when either one diminishes through inactivity (improper breathing), malnutrition, or some external factor such as injury or viral disease-the other aspect withers.

The Plain Questions section of Huangdi's Internal Classic states: ''When Yin keeps balance with Yang and both maintain a normal condition of Qi (vital energy), then health will be high-spirited. A separation of Yin and Yang will lead to the exhaustion of essential Qi."

The causes of imbalance between Yin and Yang are many and varied. Traditional Chinese medical theory regards external pathogens (xie Qi, literally, "incorrect" or "evil energy") and the state of the body's resistance to these external pathogens as the major causes of imbalance. Xie Qi (pathogens) are seen as external factors. They can arise from climatic aberrations, lack of adaptation to a changed environment, or from the "six excesses." These excesses are wind (frequently referred to as "evil wind"), cold, heat, firelike heat, dampness, and dryness. Pathogens can also be either Yin or Yang in nature. A Yang pathogen-too much dry heat for example-will decrease the body's Yang functions. Because of their interdependence, impairment of a Yang function weakens the generation and development of Yin as well. It results a so-called heat syndrome. A Yin pathogen on the other hand will diminish Yin, leading to damage of bodily Yang with a resulting cold syndrome. (As a general rule, Yin excess causes a cold syndrome and Yang excess gives rise to a heat syndrome.)

Therapy will be based on correcting the Yin -Yang imbalance. If excess Yang is the cause of a heat syndrome, it is necessary to nourish the weakened Yin by ingesting cooling Yin foods and herbs. Conversely, when a cold syndrome damages the body's Yang, Yin becomes preponderant and recourse must be made to hot, Yang foods and medicines. The general principle is thus: Treat Yang diseases with Yin foods/herbs and treat Yin disorders with Yang foods/herbs.

In order to appreciate the complexities of traditional Chinese food therapy, however, more understanding is called for. In addition to grasping the concept of Yin and Yang imbalances; we need to know something about the Five Elements of nature and their relationships to the five Zang and the six Fu organs, the concept of Qi, and the three causes of disease before delving into the principles of using food and herbal medicines.

(from The Healing Cuisine of Chine by George Ellis and Zhuo Zhao)