Chinese philosophy uses Yin and Yang to represent a wider range of opposite properties in the universe: cold and hot, slow and fast, still and moving, masculine and feminine, lower and upper, etc. In general, anything that is moving, ascending, bright, progressing, hyperactive, including functional disease of the body, pertains to Yang. The characteristics of stillness, descending, darkness, degeneration, hypo-activity, including organic disease, pertain to Yin.

The function of yin and yang is guided by the law of unity of the opposites. In other words, yin and yang are in conflict but at the same time mutually dependent. The nature of yin and yang is relative, with neither being able to exist in isolation.

The most illustrative example of yin-yang interdependence is the interrelationship between substance and function. Only with ample substance can the human body function in a healthy way; and only when the functional processes are in good condition, can the essential substances be appropriately refreshed.