*Relative Properties - Yin and Yang : The Physiology of Chinese medicine holds that the human body's life is the result of the balance of yin and yang. Yin is the inner and negative principles, and yang, outer and positive. The key reason why there is sickness is because the two aspects lose their harmony. Seen from the recovery mechanism of organs, yang functions to protect from outer harm, and yin is the inner base to store and provide energy for its counterpart.
*Basic Substance : Doctors of traditional Chinese medicine (abbreviated to TCM) believe that vital energy - moving and energetic particles, state of blood, and body fluid are the essential substances that compose together to form the human body, and the basis for internal organs to process. They are channeled along a network within the body - Jing Luo as their channels. On the physical side, vital energy serving to promote and warm belongs to the properties of yang, and blood and body fluid to moisten possesses the properties of yin.
===Yin and Yang===
In terms of the human body, yin is associated with the lower parts of the body, while yang is associated with the upper body and back. Given yin and yang’s interconnectivity, diseases are not seen as entities separate from the body, but instead are understood as states of yin and yang imbalance.
[[File:The eight principles table.png]]<br>
Yin and yang are in constant flux. If one becomes unbalanced in the body, illness occurs. For example, since yin is cold, an excess of yin can cause illnesses such as insomnia and dry-mouth. Conversely, a yang deficiency can cause cold limbs and a sickly-complexion. Good health then, is maintained by balancing yin and yang.
[[File:Yin and yang chart.jpg]]
===Five Phases theory===