The Basics of Chinese Medicine: the theory of yin & yang

Many of the theories and principles of Chinese medicine originate from Taoist philosophical thinking and belief systems. One such theory is that of Yin and Yang.  Yin and yang  is a tool that allows us to understand something or someone’s orientation and position in the world around us.Traditional Chinese practitioners use yin and yang to understand the opposites and correspondences in the human body. It is easy when looking at yin and yang to see the differences (hot/cold, fast/slow etc.). But we must always remember that there can be no day without night, no fast without slow, no hot without cold. Therefore yin and yang is always relative, one cannot exist without the other.

Some basic associations are stated below.

Yin: cold, still, dark, night, descending, internal, substance.

Yang: hot, moving, bright, day, ascending, external, function.

It is a dynamic model. For example during 24 hours, night is yin and day is yang. Just as the sun and moon move above and below the horizon, so yin and yang both wax and wane during 24 hours. This is easy to visualise if we think how less powerful the sun feels as the day progresses eventfully sinking so low as to move from day to night (yang to yin). In ourselves we are more active during the day (yang) but become less active and eventually sleep (yin) as the day progresses. 

The yin and yang symbol eloquently illustrates the theories of the model.

1. The symbol is circular reminding us the whole is composed of both yin and yang equally.
2. The black and white sections are not straight telling us that at the balance of yin and yang is in a constant state of movement and relativity.
3. The dots in the symbol tell us that the seed of yang lies within yin and the beginnings of yin are within yang and are therefore one is interdependent on the other.

Chinese medicine holds that human life is a physiological process in constant motion and change. Under normal conditions, the waxing and waning of yin and yang are kept within certain bounds, reflecting a dynamic equilibrium of the physiological processes. When the balance is broken, disease occurs. This may occur for a number of reasons, physical activity, emotional factors, diet and living conditions etc. Practitioners seek to restore harmony in the human body. The key to correct treatment is to identify the source of the disharmony and rebalance. So we must cool if there is heat, promote movement if there is stagnation, and replenish if there is deficiency etc.  


Is the patient large or thin? are they slow and lethargic? or are they restless and nervous? These are clues as to the relative balance within the patient. Is the illness of recent onset or chronic and long standing, is there heat or do they feel cold.


It is with yin and yang theory that the practitioner of Chinese medicine will begin the diagnostic process, which will then ultimately decide the treatment plan.