Glossary

The Eight Principles of Syndrome Differentiation are a core principle of Chinese medical diagnosis. They can be divided into four pairs:

• External and Internal (裡表, Li Biao)
• Cold and Hot (寒熱, Han Re)
• Empty and Full (虛實, Xu Shi)
• Yin and Yang (陰陽, Yin Yang)

The first three groups can be paired together to differentiate various syndromes, i.e. full external heat such as a fever vs. empty internal heat such as hot flashes. The last pair, Yin and Yang form over-arching categories within which the others belong: Exterior, Heat and Fullness to Yang; Interior, Cold and Emptiness to Yin. Although discussed throughout Chinese medicine since the Nei Jing, the current eight were first formally organised by Zhang Yuansu 張元素 (1151-1254) (Chace, 2022). An earlier work by Kou Zongshi 寇宗奭 (1116) proposed Eight Essentials (八要, Ba Yao) in which Yin and Yang are replaced with Correct (Zheng 正) and Pathological (Xie 邪) that is often considered to be a precursor to the current set. References:
"八綱 Ba Gang." A+ Medical Encyclopedia. Available at http://cht.a-hospital.com/w/八綱
"八要 Ba Yao." A+ Medical Encyclopedia. Available at http://cht.a-hospital.com/w/八要 Buck, C. (2009). Who Invented Bagang? Journal of Chinese Medicine 91: 12–16. Available at https://www.jcm.co.uk/who-invented-bagang.html Chace, C. (2022). Developments in Chinese Medicine from the Song through the Qing. In Lo & Stanley-Baker (eds.) Routledge Handbook of Chinese Medicine ch. 8, pp. 146 - 159. Routledge. Available at: https://www.routledge.com/Routledge-Handbook-of-Chinese-Medicine/Lo-Stanley-Baker/p/book/9780415830645