Yin and Yang

In Chinese philosophy, the body and the universe at large are best described by opposing and separate yet complementary principles – that is, yin and yang.
Yin represents the cold, the feminine, the light, the inward and downward direction and the passive. Yang represents the hot, the masculine, the dark, the outward and upward direction and the active.

The two forces are in constant interaction and opposition yet always influencing each other. For example, if one is suffering from symptoms of high blood pressure, Chinese traditional medicine would tell you that the heart has too much yang, and prescribe methods of reducing the yang or increasing the yin of the heart, after consideration of the effects of this on the other symptoms and organs of the body. Therefore, acupuncture therapies seek to increase or decrease yang or increase or decrease yin in particular body regions.