Chao, 550-630 AD (the first year of Liang Dabao in the Southern Dynasties-the fourth year of Tang Zhenguan), is the representative work of exploring the causes and describing syndromes in China.

Chao was an imperial doctor during the Great cause of Sui Dynasty (605-6 17). Zhao Feng wrote The Staging of Diseases and Pathogens, which specifically discussed the source, syndrome and prescription of diseases. It summarizes the medical experience since Wei and Jin Dynasties, with rich contents, and records the observation and understanding of diseases earlier and in more detail. This paper discusses in detail the sources of various diseases and the essentials of nine symptoms, and describes in detail the sources and symptoms of various diseases, such as internal diseases, external diseases, obstetrics and gynecology, children, five senses and so on. In addition, it also includes diagnosis, health care and guidance. This is a precious document in China's medical heritage.

Chao has profound attainments in medicine and made great contributions to the etiological and pathological diagnosis of traditional Chinese medicine. These achievements can not be achieved without seeking truth from facts, in-depth investigation and study, and dedication to science.

Chao's general theory of pathogens and stages is called the theory of pathogens and stages, Chao's theory of pathogens and pathogens and stages, etc. It was written in 6 10, with 50 volumes and 67 sections. It recorded the causes and symptoms of various diseases in detail, and discussed the diagnosis and treatment of diseases.