“Yin and yang are the laws of heaven and earth, the great framework of everything, the parents of change, the root and beginning of life and death…” (Plain Questions, Chapter 5).
The theory of yin and yang is the basic guiding principle of all Chinese medicine. Yin and yang is a descriptive dialectic into which all things may be categorized, such as day (yang) and night (yin). Chinese medicine applies this yin/yang dialectic to the human body where as health is the balance of yin and yang. The yin element of the body is nutritive, substantial, female, holding, cold, and yielding. The most yin substance of the body is blood. The yang element of the body is active, moving, functioning, male, warm, and dynamic. The most yang substance of the body is qi (energy).
The balance and dynamic of yin and yang is guided by a five rules of observable phenomenon. Yin and yang oppose each other as cold opposes heat. Yin and yang are interdependent upon each other; there is no concept of cold without a concept of heat. Yin and yang transform into one and other, the emergence of day out of night. Yin and yang consume each other and support each other. Yin and yang are infinitely divisible into one and other. The morning is the yang within yang, the afternoon the yin within yang, the night the yin within yin, the breaking day is the yang within yin.
These principles of yin and yang guide the diagnosis and the basic treatment of all patients. At the root of your primary imbalance is an imbalance between yin and yang. The first step in gaining health is to regain the yin and yang balance.