Traditional Chinese Medicine
One of the most basic principles of Traditional Chinese Medicine is the idea of Yin and Yang, the philosophy of opposites and balance. According to this philosophy, everything in the universe is balanced by it’s own polar opposite. Yin is seen as female, dark and cold, while Yang is male, light and hot. In Chinese practice, many illnesses can be explained by an imbalance of Yin and Yang.
Another fundamental concept is the philosophy of the five elements: wood, fire, earth, metal and water, also called the five phases theory. Each of these five elements is closely related to two (Yin and Yang) body organs. Yin organs are the more solid ones, such as the kidneys, and Yang organs are the hollow ones, with substances merely passing through. Here is a list of the five elements and their relation to body organs:
Fire: heart (Yin) & small intestine (Yang)
Earth: spleen (Yin) & stomach (Yang)
Metal: lungs (Yin) & large intestine (Yang)
Water: kidneys (Yin) & bladder (Yang)
Wood: liver (Yin) & gall bladder (Yang)
Every organ is associated to a color, an element, an emotion, a season, and a taste. For example, liver and gallbladder is a wood element, therefore related to spring, the color green, a sour taste, angry emotions, and the tendons and eyes.
Source: Encyclopedia of Natural Healing (Second Edition)