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[Gancao (Licorice Root)]
The flavor is sweet, and the nature is neutral. It primarily treats disorders of the five zang organs and six fu organs caused by pathogenic cold or heat. Sweetness can tonify the Middle Qi (Vital Energy of the Spleen and Stomach); when Middle Qi is robust, the essence of the zang and fu organs can be distributed throughout the body, thereby driving away abnormal qi. It strengthens sinews and bones, promotes muscle growth, and doubles physical strength. For those with insufficient form (physical weakness), supplementation should be done with substantial flavors; the sweetness of Gancao is the correct flavor of Earth and is the most concentrated, hence its efficacy is so profound. It treats metal wounds; since the Spleen governs muscles, tonifying the Spleen enables it to fill out the muscles. It detoxifies. Sweetness is the most upright flavor among the five tastes; uprightness in flavor implies uprightness in qi and nature, thus it can eliminate toxins. Long-term consumption leads to a light body and longevity. This represents the function of tonifying the Post-Heaven (Acquired) foundation.
This passage discusses treatment based on flavor. The sweetness reaches its extreme in Gancao. Sweetness belongs to Earth, so its effects are all centered on the Spleen. The Spleen is the master of the Post-Heaven foundation, and the five zang and six fu organs receive qi from it. When Spleen qi is abundant, the five zang organs benefit in a cyclical manner.

[Sheng Dihuang (Raw Rehmannia Root)]
The flavor is sweet, and the nature is cold. It primarily treats fractures and dislocations due to falls, internal injuries, expels blood bi (obstruction), and exerts the effect of promoting blood circulation. It fills the marrow; sufficient blood can transform into essence, and the black color corresponds to the Kidney. It promotes muscle growth. The Spleen controls blood; when blood is abundant, muscles also become full. Decocted as a soup, it eliminates cold-heat accumulations; sufficient blood scatters pathogenic factors, and flowing blood dissolves stagnation. It removes bi syndrome. Harmonious and smooth blood ensures unobstructed meridians. Using it raw is especially effective. Blood values circulation, not cloying stickiness; therefore, before the middle ancient period, few people used Shu Dihuang (Prepared Rehmannia Root). Long-term consumption leads to a light body and preservation of youth. This represents the function of nourishing blood.
The color and substance of Dihuang resemble blood, so upon entering the human body, it specializes in nourishing blood. When blood is nourished, Yin qi becomes harmonious, eliminating diseases of dryness and spasms. Ancient formulas only included Gan Dihuang (Dried Rehmannia) and Sheng Dihuang (Raw Rehmannia); there was never any use of Shu Dihuang (Prepared Rehmannia). Shu Dihuang is a processing method developed after the Tang Dynasty. Adding it to Chinese herbal medicines for warming and tonifying the Kidney meridian is quite appropriate. However, it is very unsuitable for decoctions and formulas for nourishing blood or clearing heat. This is because Dihuang specifically relies on its cool, slippery, and circulating nature; once processed into Shu Dihuang, it becomes cloying and stagnant, losing its coolness and completely losing its original nature. Furthermore, among the 113 formulas in Zhang Zhongjing's "Treatise on Cold Damage" (Shanghan Lun), only Fumai Tang (Pulse-Recovering Decoction) uses Dihuang. This is because in cold damage diseases, pathogens enter from the exterior, and cloying stagnation is strictly contraindicated. Even if tonification is used, it must possess dispersing and expanding properties to be included in the prescription. Otherwise, pathogens will move inward, causing lingering harm. Nowadays, people see symptoms that slightly suggest deficiency and immediately treat Liuwei Dihuang Wan (Six-Ingredient Pill with Rehmannia) as a common remedy, killing countless people, which is a cause for deep sighing.