Through the clinical experiences of four examination methods, such as inspection, auscuhation-olfaction. interrogation (history taking) and palpation ( including pulse taking), the eigh! principles are employed in the analysis and categorization of disorders based on location, nature of disease and relation to pathogenic factors. These eight principles are yin, yang, interior, exterior, cold. hot. deficiency and excess. They form the identification and descriptive part of the disorder.
Although the indications and manifestations of diseases may appear complex, the fundamentals can be described and categorized using the eight principles. For example, location or depth of the disorder, and whether it is exterior or interior. As for the nature of the disorder, it is either hot or cold. In terms of pathogenic and upright defensive factors, it's either the weakness in the upright, defensive factors or the excess of the pathogenic factors. In terms of the overall category of disorders, they are either yin syndrome or yang syndrome. The purpose of the eight principles is to separate disorders into exterior and interior svndromes, cold and hot syndromes, excess and deficiency syndrome: and via and yang syndromes as the main differentiating factors in clinical diagnosis. Of the eight principles, six fall under the category of yin and yang. Therefore, exterior, hot and excess are considered yang syndromes and interior, cold and deficiency syndromes are considered
yin syndromes.