In herbal medicine we often talk about herbs that harmonize. Harmonize what? The key herb that harmonizes is zhi gan cao. You know, stir fried with honey Glycyrrhizae radix.
Zhi gan cao is often paired with other herbs like, da huang, gan jiang, gui zhi, or bai shao. Why is that?
Zhi gan cao is a sweet, mildly warm herb that nourishes and tonifies. It is an earth herb that nourishes fluids and tonifies function of the stomach and spleen. It tonifies the center.
Plain Questions, The Center generates Dampness, Dampness generates Earth, Earth generates Sweet, Sweet generates the spleen, the spleen generates the flesh.
It transforms, Earth corresponds with transformation and the sweet taste.
The last eighteen days of each season belongs to earth. This implies that without the earth to give birth to the myriad of things there would be death. This also implies that without earth the seasons could not transform from one to the next.
Plain Questions, The spleen, does not have a season that it governs.
Plain Questions, The spleen is earth, it rules the central region, it holds fast to the four seasons, and extends to the four viscera. Eighteen days from each season are entrusted to it, but it does not have a season all its own.
Dong Zhongshu called the spleen, The lord of the five elements. It is the ruler because all the other elements cannot come into being without earth.
The spleen and earth makes the transition of yang and yin qi possible from season to season.
Because it is the ruler it corresponds to the element earth, and it is used for the same reason in herbal medicine.
Sweet warm zhi gan cao is the herb that is the most representative for tonifying the earth. The sweet taste tonifies but also nourishes, it allows for the smooth transformation of qi.
Did you ever wonder why there is no zhi gan cao in the formula da chai hu tang?
Da chai hu tang
chai hu 24 huang qin 9 ban xia 12 sheng jiang 15 da zao 9 bai shao 9 zhi shi 6 da huang 6
It would hold back the needed descending action of the yang ming stomach family. After the stool has started to move and there is no more heat and vexation, naturally put it back in and remove the zhi zhi, and or the da huang.