The theory of yin and yang
The theory of yin and yang is an ancient philosophical concept used in traditional Chinese medicine. Through living, practice and observation of every kind of natural phenomenon, people came to realise that two opposites exist in all things, and furthermore, that their interaction promotes the occurrence, development and transformation of things. Yin and yang always has the following characteristics:
All things and phenomena in the natural world contain these two opposite components. The heaven is yang, while the earth is yin; outside is yang, while inside is yin; movement is yang, while stability is yin; day is yang, while night is yin; heat is yang, while cold is yin; rising is yang, while falling is yin; a rapid pulse is yang, while slow pulse is yin.
Yin and yang not only oppose each other, but also contain each other, without the other, neither can exist. Without outside, there would be no inside, and vice versa. TCM holds that “functional movement” belongs to yang and “nourishing substance” belongs to yin, and these are always in the state of dynamic balance. If the yin and yang of the human body separate from each other, then life will come to an end.
3) Waxing and Waning
Yin and yang are not stagnant but always in a dynamic state of change, while yin wanes, yang waxes, and vice versa. Think of the change of seasons for example, the weather gets warm when winter gives way to spring, and hot when spring gives way to summer, during which time yin wanes, while yang waxes. When summer is greadually replaced by winter again, yang wanes while yin waxes.
Yin and yang will transform into each other under certain conditions. For example, in the course of suffering from a disease, the patient may run a high fever, with a red complexion, feel irritable and restless with a rapid pulse. All of a sudden, he may feel listless, his temperature falls, his face turns pale and pulse becomes weak. This is a transformation between yin and yang. Alternating fever and chills is also a symptom of malaria.
Either yin or yang can be still divided into another pair of yin and yang. For example, day is yang and night is yin, but both day and night can be further divided: the period from dawn till noon is the yang aspect of yang; the period from nood till dusk is the yin aspect of yang; the period from dusk till midnight is the yin aspect of yin; the period from midnight till dawn is the yang aspect of yin.
In TCM diagnosis, it is important to ascertain whether a disease is yin or yang. In observation, those with a bright complexion are patients of yang character, while those who look dark and gloomy are of yin character. In listening, those who have a loud and clear voice have yang character, while those with a low and weak voice a yin character. Those who have a fever, feel thirsty, suffer from constipation and have a rapid pulse are of yang, while those who have an aversion to cold, don’t feel thirsty, have loose stools and slow pulse are of yin.