The yin yang Theory

In Chinese culture, the yin-yang theory is deeply rooted. It is the ground philosophy which serves as the basis for any conceptual thinking that Chinese people have. Therefore it is also play an important role in Traditional Chinese Medicine(TCM) . It is used to diagnose, prescribe and treat any illnesses.
Then What is the Yin-yang theory?

The Chinese believe that originally everything in this universe is made of Qi ( Prana, Mana), it is because of this Qi moves, then it becomes polarized into two poles, Yin and Yang. Then All material things are basically created from the movements and variation of these Yin-Yang interaction. If you closely see the nature, you may find that Yin-Yang polarization apply to everything in the form of  Sun and moon, fire and water, Heat  and cold, and so on.

In this theory, originally what we call yin or yang is related to its position relative to the sun. When a side facing to the sun it is called Yang, when opposite to the sun is called Yin. Therefore, everything that Yang should be warm, active, bright and up-flaming, and everything that is Yin should be Cold, dim, static and downward-moving. In this way, every phenomena and this are grouping based on its Yin or Yang properties.
However, this categorization process is relative and not absolute. It means that the Yin or Yang properties of things are subject to change and vary according to time and application. Take for Spring or summer for  example, spring is colder than summer, therefore spring is Yin and summer is Yang. When comparing with winter, spring is warm, then spring is Yang and winter is Yin.

In addition, Yin-Yang properties of things and phenomena can be divided into smaller yin-yang infinitely. Take a daytime and night for example, daytime is Yang and night is Yin, but since Yang-qi ascends in the morning and descends in the afternoon, then morning pertain to Yang( Yang within Yang) and afternoon to Yin ( Yin within Yang).

Now, how Yin and Yang relate to each other?  The Yin and Yang are always in opposite side, they always repelling and restraining each other. In nature, Yin and Yang aspects are in balance and maintaining the relative equilibrium of things. If one side is strong the other is weak, and the strong one will restrain the weak side, then equilibrium is breaking. That is one of the basic principles in Traditional Chinese Medicine which is called “the contrary treatment”.  

When a person get cold ( Yin), the treatment would be administering drugs with  hot in nature (Yang), While febrile disease with drugs cold in nature (Yin)

Even though Yin and Yang are in opposite, it is cannot exist alone. There will be no yin without Yang or the other way around. In TCM, there is a saying “ Yang alone cannot exist” and “Yin alone cannot grow”. The interesting things are Yin-Yang aspects of things can transform to each other under certain condition.
In patients with Yang deficiency, the TCM doctor may supplementing Yin to generate Yang and may supplementing Yang to generate Yin. This may be shown in a patients with blood deficiency can be treated with supplementing chi to generate blood, and those with qi deficiency may be treated with supplementing blood. It is called “ Drawing Yang from Yin” and  “Drawing Yin from Yang”.

When Yang is developed in an object, the Yin sides wane, and when the Yin rise, the Yang side slide.  Under normal condition this activity maintains a dynamic balance between Yin and Yang. That’s why in nature, when something reach its peak, it begins to decline, and the other side begin to rise.