The concept of Yin and Yang is critical for understanding Traditional Chinese Medicine theory. The easiest way to understand these concepts is to look at the Chinese characters themselves, and the ideas they are trying to capture.
This is the symbol for Yin. The left side of the character represents a hill, and the bottom right portion of the character represents a cloud. Therefore, the character for Yin depicts the shady side of a hill. This side of the hill is darker, cooler, more moist.
This is the symbol for Yang. Again, the left side of the character represents a hill, and the right side of the character represents a sun over the horizon, with rays of light. Thus, the character for Yang depicts the sunny side of a hill. This side of the hill is brighter, warmer, more dry.
These concepts (which are called YinYang in Chinese, not Yin “and” Yang as we say in English) represent two opposite, but complementary and interdependent, qualities.
Some basic YinYang correspondences:
YinYang is not a static. Rather, it represents phases of cyclical movement, or stages of transformation. For example, day is Yang, but it turns into night, which is Yin. In the morning, as the sun warms the dew on grass, the water is turned into vapour (Yang). As the sun goes down and the air cools, that same vapour re-condenses back into dew (Yin).
This symbol is called the “supreme ultimate”, and represents the relationship, and the interdependence, of Yin and Yang. The main points represented in this symbol are:
a) Yin and Yang form a whole and are complementary, even though they represent opposites.
b) Within Yin and Yang are the seeds of each other. This is what the black and white dots represent.
c) Nothing is totally Yin, nothing is totally Yang.
d) Yin changes into Yang, Yang changes into Yin.
In Traditional Chinese Medicine theory we apply YinYang to the human body.
Illness arises if YinYang become out of balance. There are four possible states of imbalance that create disease:
a) too much Yin / excess Yin (ex. phlegm accumulation, stagnation of Blood)
b) too much Yang / excess Yang (ex. fever, inflammation)
c) not enough Yin / deficient Yin (ex. dryness, hot flashes due to lack of proper cooling)
d) not enough Yang / deficient Yang (ex. feeling cold, fatigue)
The organ systems (the ZangFu and the Extra-ordinary organs) and a complex interplay of Blood, Qi, and Body Fluid, together with factors such as diet, lifestyle, exercise, emotions, environmental changes, and pathogenic invasions can influence our balance of Yin Yang.