Founder’s Note : This is part of a series of articles we’ll be releasing here about the theory and herbs of the Tang ye jing. The enthusiasm and scholarly integrity of the author – regular contributor Joshua Park, DSOM, LAc – will make this a thought provoking and engaging read that we hope you’ll share with friends and colleagues. Joshua is eager to hear your feedback, either here on the site or on our Facebook page.
We’ll continue working in the metal class of herbs…
All sour belongs to metal, for it is governed by Wuweizi, and Zhishi is wood,Chi is fire, Shaoyao is earth, and Shuyu [better known to modern practitioners as Shan Yao] is water.
Next in our exploration of the 25 Herbs of the Tang Ye Jing, Next, we consider Wu Wei Zi.
As the Metal of Metal, Wu Wei Zi is the quintessence of the sour flavor, and it is the perfect herb to illustrate why the Tang Ye Jing ascribes the action of sour to Metal. Let’s begin with the Shen Nong Ben Cao Jing’s entry for Wu Wei Zi:
Wu Wei Zi’s flavor is sour, [its temperature] is warm. It governs augmenting qi, cough reversal, surging qi, taxation damage, debilitating emaciation, tonifies insufficiency, strengthens yin, augments male essence. It grows in mountain and valleys.
This description is in keeping with the statement in Su Wen Chapter 22 that when the Lungs desire to be gathered, urgently eat sour to gather them (肺欲收，急食酸以收之).
Wu Wei Zi is most frequently seen in the SHL not in a formula of its own, but as half of a two herb modification for the treatment of cough.
In Line 96, for example, when using Xiao Chai Hu Tang (小柴胡湯) to treat a Shaoyang pattern, we are told that if the condition presents with a cough, we are to remove Ren Shen, Da Zao, Sheng Jiang and add Gan Jiang and Wu Wei Zi. This same modification occurs in Line 316, which describes a Shaoyin pattern treated by Zhen Wu Tang (真武湯). The line states that when there is a cough, Gan Jiang and Wu Wei Zi as well as Xi Xin are added.
We can understand these modifications in light of the statement in Su Wen Chapter 38, that it is not only the Lung which causes cough, but potentially any of the Five Zang and Six Fu (五藏六府，皆令人欬，非獨肺也). These modifications show us how to elegantly treat both the branch (cough) as well as the root (the underlying imbalance).
This combination of two or three herbs of a particular action, offset with an herb with an opposite action, is one of the signatures of the formula found in the Tang Ye Jing.
It is also one of the signatures of Zhang Zhongjing’s formulas! We can also see the combination of acrid (Gan Jiang and Xi Xin) and sour (Wu Wei Zi) as promoting the physiology of the Lungs. We know from basic Chinese Medicine physiology that the Lungs are in charge of dissipating and disseminating qi, functions that are promoted by outward movement of the acrid flavor. The gathering movement of the sour flavor, meanwhile, promotes the Lung’s descending function as well mirroring the action of inhalation and drawing in air.
We can also understand this combination in light of Su Wen Chapter 22, which states that acrid purges the Lungs while sour tonifies them (用酸補之，辛寫之); thus this combination is simultaneously draining pathological excess while also protecting the qi of the Lungs. The three herb combination of Gan Jiang, Xi Xin, and Wu Wei Zi also features in the formula Xiao Qing Long Tang (小青龍湯), where it is used to restore normal function to the Lungs, and when combined with Ban Xia, to remove stagnant fluids from the upper burner.
There is a lot more to say on Wuweizi, but much of it only makes sense once we’ve explored the other herbs.
My hope is, after the whole series is done, to create an expanded version as an ebook that would add more information about specific formulas and deeper analysis that’s only possible when things are complete.
But, before that, on to our last herb in the metal class – Shanyao – next week!