Jin Gui Shen Qi Wan (JGSQW) is the quintesential Yang tonic. The fact that this formula is based largely on the quintesential Yin formula Liu Wei Di Huang Wan (LWDHW) came as quite a conundrum to me during my studies. The explaination that the inter-transformation of Yin into Yang is entirely and profoundly correct, but at the same time is a little wanting for specific details. Bensky & Barolet included a prelude to their chapter on JGSQW(1). It states:
In chapter 5 of Basic Questions it is noted that “the lesser [Kidney] fire generates qi.” This formula combines herbs that nourish the yin with those that tonify the yang, not so much to tonify the Kidney fire itself, but as a means of generating Kidney qi. It is therefore named the ‘Kidney Qi Pill’ rather than ‘Kidney Warming Pill.’
I believed herbal formulas to be frightfully delicate for a fundamental Yin tonic to be transformed into the poo-bah of Yang tonics by the meager addition of a pinch of fu zi and a dash of gui zhi. Though I have yet to come across another classic herbal fromula, which obeys this same transitory property.
I offer another explaination for your critique. Consider the campfire analogy of the Minister Fire; Kidney Yin (wood) is consumed to produce Kidney Yang (fire). When Kidney Yang is vacuous there is a relative abundance of Yin. Yin repletion manifests in signs and symptoms of dampness: swollen tongue with a moist coating, edema, excessive urination, etc. At this point, the imbalanced Yin becomes saturated with dampness; much the same as campfire wood burns dimly when it is wet. Furthermore the wood typically burns dirty, emitting alot more smoke than dry wood. This smoke is also analygous to an accumulation of turbid Yin.
To remedy the problem of a wet campfire, consider adding dry wood and a dash of gasoline. The gasoline burns aggressively lighting the dry wood, which eventually burns off the dampness in the wet wood to produce a steady fire. In the case of JGSQW, the LWDHW is akin to the dry wood, while fu zi and gui zhi are likened to gasoline.
(1) Bensky & Barolet, Chinese Herbal Medicine, Formulas & Strategies, Eastland Press, 1990, pp. 275.
