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Gypsum Fibrosum (Shigao)

Pungent, sweet; slightly cold in nature. Its flavor and qi are both thin and light, heavy in weight and sinking in action, possessing a descending property; it is yang within yin. Non-toxic. It is produced abundantly in Qingzhou and Xuzhou. It fears iron and is adverse to *Aconitum carmichaelii* (Macono/Badou - note: text says Mangcao Badou, likely referring to specific toxic herbs or processing constraints, strictly translating as Mangcao and Badou), and *Croton tiglium* (Badou). Those with fine grain and bright white luster are of the highest grade; it becomes effective only after being calcined in fierce fire until soft. It must be ground into an extremely fine powder for use in decoctions or liquids. Egg white (*Jizi*) serves as an assistant drug; it enters the Lung, Stomach, and Sanjiao meridians. The pungent flavor can induce sweating, release the muscle layer, ascend to treat headache; the sweet flavor can moderate the Spleen, benefit Qi, generate fluids, stop thirst, and dissipate irritability. Therefore, whether wind pathogen injures Yang or cold pathogen injures Yin, they can generally be cured by releasing the muscle layer. Whether due to Stomach heat causing polyphagia or Stomach heat preventing eating, only clearing Stomach Fire can cure them. Zhang Zhongjing added it to formulas, naming it Baihu Tang (White Tiger Decoction) (The anterior body is the pathway of the Stomach meridian, and the chest is the chamber of the Lung. When pathogen is in the Yangming meridian, the Lung is constrained by fire, so Gypsum's pungent-cold nature is used to clear the Lung, hence named White Tiger). Li Dongyuan (Yilao) called it a major cold agent. It is contraindicated for those with weak Stomach and inability to digest food, and forbidden for those with blood deficiency and bodily fever. (This analogy resembles the White Tiger syndrome; misusing Baihu Tang leads to death, do not take it lightly.) Ground alone into powder and mixed with vinegar to form pills, it is highly effective for treating food stagnation and phlegm-fire. For severe epigastric pain, swallowing the powder brings immediate relief.

(Chen Jiamo) Commentary: Zhu Danxi said: "I have observed that the naming of medicines often has aspects that are not immediately obvious. There is much meaning involved; students must examine this carefully." For example, those named by color include Rhizoma Curcumae Longae (Dahuang), Flos Carthami Tinctorii (Honghua), Radix Bupleuri (Baiqian - *Note: Baiqian usually refers to Saussurea root, but context implies color*), Folium Isatidis (Qingdai), Fructus Pruni Mume (Wumei). Those named by aroma include Radix Aucklandiae (Muxiang), Lignum Aquilariae Resinatum (Chenxiang), Lignum Santali Albi (Tanxiang), Fructus Foeniculi (Huixiang), Moschus (Shexiang). Those named by substance include Cortex Magnoliae Officinalis (Houpo - *Text says Nongpu, likely variant/typo for Houpo*), Rhizoma Zingiberis Recens (Shengjiang), Poria (Fuling), Radix Rehmanniae Preparata (Sheng/Di Huang). Those named by shape include Radix Ginseng (Renshen), Os Spinae Canis (Gouji), Radix Aconiti Lateralis Preparata (Wuhui), Bulbus Fritillariae Cirrhosae (Beimu), Fructus Loropetal Chinensis (Jinlingzi). Those named by taste include Radix Glycyrrhizae Uralensis (Gancao), Radix Sophorae Flavescentis (Kushen), Radix Gentianae (Longdancao), Folium Phragmitis Communis (Danzhuye), Acetum (Kujiu). Those named by function include Bulbus Lilii (Baihe), Radix Angelicae Sinensis (Danggui), Rhizoma Cimicifugae (Shengma), Radix Saposhnikoviae (Fangfeng), Natrii Sulfas (Xiaoshi). Those named by season include Rhizoma Pinelliae Ternatae (Banxia), Herba Artemisiae Scopariae (Yinchen), Caulis Malvae Tiliifoliae (Dongkui), Yin Ji (Tiger Rooster at Yin hour), Herba Prunellae Spicatae (Xiakucao). Gypsum, after calcination, when ground fine and mixed with vinegar to seal alchemical furnaces, is more tightly sealed than Lithargite (Shizhi). Without Gypsum, how could this function be achieved? This name derives from both its substance and function, consistent with Shizhi. Yan Xiaozhong erroneously treated Calcitum (Fangjieshi) as Gypsum. Moreover, Gypsum is pungent and sweet, originally a herb for the Yangming meridian, which governs the muscles. Its sweetness moderates the Spleen, benefits Qi, stops thirst, and removes fire; its pungency releases the muscle layer, induces sweating, and ascends to the head. It also enters the Taiyin and Hand Shaoyang meridians. Fangjieshi, however, is merely heavy, solid, and cold in nature. Where is the 'paste' it produces that could serve as the chief agent for these three meridians? If physicians seek efficacy, is it not difficult?

After the entry for Radix Anemarrhenae Asphodeloides (Zhimu) in Volume One (Chen Jiamo) Commentary: Suitable for reference.