Eight-class syndrome differentiation: doctors use eight classes to analyze and synthesize the data of various diseases obtained through diagnosis, so as to distinguish the epitopes of diseases, the cold and heat of the nature of diseases, the ups and downs of the dispute between evil and righteousness, and the yin and yang of disease types, which is called eight-class syndrome differentiation.
There are eight types of syndrome differentiation in TCM: yin and yang, exterior-interior, cold-heat and excess-deficiency, which are actually six types of syndrome differentiation, while yin and yang are the general categories, exterior-interior, heat and excess-deficiency are yang; Internal, cold and deficiency are yin. Therefore, Zhang Jingyue, a physician in the Ming Dynasty, said in The Complete Book of the Pure Moon: "Although the medical ways are complicated, in a word, they are just yin and yang." It means that although the medical road is broad, it is yin and yang if summarized in one sentence.
Therefore, in the process of treating diseases, it is particularly important to distinguish between exterior and interior, cold and heat, and excess and deficiency.