I’ve been doing some research for a book on 養生 yang sheng/nourishing life, and one of my favorites for many years has been Yojokun, by Ekiken Kaibara. Kaibara was a neo-confucianist philosopher, samurai and physician in the 17th century. As well as setting out laws of maintaining health, Yojokun also discusses many of the Jin-Yuan medical theories that were popular at this time. Ekiken considered himself a follower of Li Dongyuan, originator of the spleen-stomach current, which makes sense considering his focus on diet and digestive health. But he was very critical of Zhu Danxi’s (Zheng-heng) theory of supplementing yin.
“On what classic is the theory of superfluous yang and insufficient yin based? I myself have never seen such a book. If these are Dan-xi’s words, they are nonsense and difficult to believe. They go against the principle of the dao of change. If you follow Dan-xi’s methods and concentrate on supplementing yin, you will hurt your spleen and stomach and damage your fundamental health. If yang flourishes, yin will of itself live long. If you supplement yang qi, yin blood will be produced of itself. But if you try to supplement insufficient yin by taking xuan shen, huang bai and zhi mu for a long period, you will only damage your true yang, weaken your stomach qi, and inhibit the production of blood.”