This method dates to at least 300 BC - 500 BC. Visual characteristics are mentioned in The Yellow Emperor’s Classic of Internal Medicine. The practitioner observes the entire body looking for abnormalities. Raises and depressions in places they should not be are significant. Dry or damp patches mean imbalance. Facial colors other than glowing pink (which could also mean sunburn or pregnancy) are a sign of imbalance. General and local color are also important. For instance, a saffron like yellow aroundthe navel indicates severe deficiency of the spleen.
There are also systems of correspondence between the face and other parts of the body. For example, one system associates the major regions of the face with the Yin organs. The Heart is reflected by the forehead and the Kidneys are reflected by the chin. Another system uses the area surrounding the eyes and yet another is based on regions on the eye itself.