This fascicle is named as Si Jong Yong Ron because it puts an emphasis on attitude in diagnosis and is divided into two chapters, chapter 1 dealing with the principle of how to distinguish differences and how to compare similarities in classification, chapter 2 emphasizing an importance in classification alike examplfying similar symptoms of diseases in spleen, stomach, and lung. Accurate diagnosis should be at first done for proper treatment, classification should be accurate for precise diagnosis, and calm and intensive observation to a patient could give rise to precise classification. This fascicle has a great significance in that it supplies a detailed explanation about the principle for precise classifiication.