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Chinese Medicine Theory – Yin Yang

10 February 2014

The concept of Yin-Yang is one of the most fundamental theories of Chinese medicine. It is a truly ancient Chinese philosophical concept that was in use in other fields of classical Chinese science before it was adopted in medicine.

The earliest reference to Yin and Yang was most likely in the Yi Jing (sometimes called the I Ching), or the “Book of Changes”, dating back to around 700 BC.

By the Warring States period (476-221 BC), Yin Yang was being employed alongside Wu Xing (5 Element) theory, to understand natural processes, including those within the human body in both health and disease.

Symbolism of Yin and Yang

The Chinese characters of Yin and Yang can have numerous interpretations but one of the most commonly used translations is shady side of the hill (for Yin); and sunny side of the hill (for Yang).

Yin Yang characters

Chinese characters for Yin Yang

The first symbols associated with Yin Yang were simply a broken line and unbroken line. These formed the bases for the trigrams and then hexagrams of the Yi Jing.

Yin Yang lines

Unbroken (Yang) and Broken (Yin) lines of the Yi Jing

The symbol most widely associated with Yin Yang today comes from the Taoist representation of the Yin Yang principle, the Taijitu (literally “diagram of the supreme ultimate”). It is still recognised as the universal symbol of Taoism.

Yin Yang
The Taoist Taijitu symbol

Yin is the black side with the white dot within it. Yang is the white side with the black dot within it.

What is Yin Yang?

Yin and Yang is a concept used to describe relationships between two things. They are used to explain how seemingly opposite forces are actually interconnected and interdependent.

Yang is usually taken to be the more active of the two. Yin is taken to be the more passive. So hot, up and light would be Yang compared with cold, down and dark as Yin.

While Yin and Yang may be seen as opposites, such as male and female, activity and rest, day and night, hot and cold, dry and damp, etc,  they are also necessarily complimentary. They are two halves of the whole.

Everything can be broken down into either yin or yang relative to something else, and one only exists relative to the other. Hot is only hot relative to something cold. The front is only the front relative to the back.

The laws of Yin Yang

Below are the five essential laws of Yin Yang. They are all clearly visible within the Taijitu symbol.

1) Everything has a Yin and a Yang aspect.

For example, temperature has hot and cold, weight has light and heavy, position has above and below or in front and behind, gender has male and female, etc. This is represented in the Taijitu as the one circle having two halves.

2) Yin and Yang are interdependent.

They cannot be separated. Without either one the circle is not complete.

While Yin and Yang are the opposite of the other, they are relative aspects of the same thing. One only exists relative to the other. As mentioned before, something is only hot relative to something cold.

3) Yin and Yang transform into each other.

There is constant transformation from Yin into Yang and back into Yin again. This can be seen in the Taijitu symbol as the head of Yang becomes the tail of Yin etc.

Shortly after Yang reaches its peak, it transforms into Yin and vice versa. The stillest, coldest, darkest time of night is just before dawn.

4) Yin and Yang control each other.

They each prevent the other from becoming too excessive. Cold prevents hot from becoming too hot, and rest prevents activity from burning out.

They are an equal match for each other. If one was to be in a greater supply than the other, the wheel would become unbalanced.

5) Yin is present within Yang, and Yang is present within Yin.

Within Yang, some Yin is present, and likewise there is a little bit of Yin present within Yang. This is the eye of the fish in the symbol. This would be a man’s feminine side or a woman’s masculine side. Fatigue (Yin) due to fever (Yang) would be considered Yin within Yang.

This allows Yin and Yang to be continuously sub-divided. So each Yin or Yang aspect has its own Yin and Yang aspect.

Yin and Yang in Chinese Medicine

This theory sits as one of the core concepts of Chinese medicine. In understanding health and disease, it is combined with the other core theories of Chinese medicine primarily the 5 Elements and 6 Qi.

Yang and Yin are metaphorically represented as fire and water, from a Five Element perspective. From a Six Qi perspective (that is Heat, Cold, Dry, Damp, Fire and Wind) the yang influences are Heat, Fire and Dryness; while the yin influences are Cold, Wind and Dampness.

Yang illnesses are those categorised as aggressive, fast moving, acute and involving heat. Yin disease is more chronic, slow moving, less forceful, and cold in nature.

Yin-Yang is used in diagnosis, and in treatment when selecting acupuncture points, herbal medicines and foods. If one of either Yin or Yang becomes overabundant or insufficient, the wheel becomes unbalanced and there will be ill health.

The behaviour of various bodily functions, tongue, pulse and abdomen qualities (see diagnosis in Chinese medicine), and the presence of different symptoms, allows the practitioner to determine where in the body Yin or Yang are in a state of excess or deficiency. Treatment then sets out to restore balance by tonifying the deficiency, or reducing the excess, or both.

Function versus matter

One of the very important divisions of Yin and Yang within the human body, but also within any living organism, is that of function versus matter. This represents life itself.

Here, the physical form is Yin. It is the matter that the organism is made up of. That which gives life to the otherwise cold, immobile, life-less mass is Yang.

Yang is the force that causes the matter to move, have warmth, circulate, reproduce, and have purpose and intention.  The point of death is the moment yang is completely exhausted and separates from Yin.