Yin and Yang
Yin and Yang are the fundamental forces of the universe in China, Japan and many east Asian cultures. In time, they were adapted for use within medicine. In Traditional Chinese Medicine, energy, or qi, is composed of Yin and Yang. These must also be in balance for good health.
Yin and Yang are associated with opposite forces, such as hot and cold, light and dark, and stillness and movement. Neither can exist in isolation, but they mutually influence each other. Yin-Yang explains the body’s structure and function. The body is seen as a set of connected systems governed by the balance between Yin and Yang.
The theory is used to diagnose and treat illness. For instance, the properties of drugs are classified as Yin or Yang. Appropriate drugs are then used to re-establish balance between the two forces in the body.