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Muzi (Rhizoma Anemarrhenae) is a herb that clears heat from the Qi level of the Lung, Stomach, and Kidney meridians. Jiegu (Zhang Yuansu), Dongyuan (Li Gao), and Danxi (Zhu Zhenheng) all regarded Muzi together with Huangbai (Cortex Phellodendri) as Yin-nourishing agents, and later generations treated them as tonics. Although the moistening property of Muzi is not as drying as Huangbai, its cold and slippery nature directs downward; while it can indeed eliminate heat and generate Yin, fundamentally it lacks the ability to tonify and augment insufficient Yin. Even when used to drain pathogenic fire, one should stop at the appropriate point. Otherwise, excessive descending action will damage the Spleen and Stomach and secretly deplete True Yang, just as Libinhu (Li Shizhen) stated.

Many formulas in *Shanghan Lun* do not contain Muzi. Baihu Tang contains Muzi but does not treat thirst; only after adding Renshen (Radix Ginseng) does it begin to treat thirst. This is because Yangming heat is exuberant, and clearing heat is indeed crucial; however, Muzi alone lacks the ability to generate fluids and nourish Yin. Adding Renshen during the process of clearing heat allows the disease to be eliminated and the healthy Qi to recover immediately. The meticulousness of this intention surpasses even *Qianjin Fang* and *Waitai Miyao*.

In Guizhi Shaoyao Zhimu Tang, Zhang Zhongjing's use of Zhimu aligns with the description in *Ben Jing*: "Eliminate pathogenic factors, limb edema, and promote water discharge." Zou's explanation, which merely considers Zhimu as treating fire obstruction in the lower jiao, is superficial. Let us supplement this by citing other theories: Zhang Yinan said, "The outer skin of Zhimu has hairs, thus it eliminates pathogenic factors from the skin and hair; the flesh is thick and the skin yellow, acquiring the Earth qi, thus it treats limb edema." Zhang Shiwang said, "'Eliminate pathogenic factors, limb edema' refers to damp-heat and water qi." Ye Tianshi said, "The Kidney dislikes dryness; dryness leads to dysfunction of opening and closing, causing water to accumulate. Zhimu is cold and slippery; its slipperiness opens the gateways, allowing water to flow down naturally." Synthesizing these three explanations, the rationale for using Zhimu in this formula becomes clear.

Zou stated, "The Spleen governs the ascending of clear Yang, and the Stomach governs the descending of turbid Yin; both belong to Earth and fear dampness. Baizhu flowers in early summer and fruits during the Dog Days, manifesting its efficacy precisely during the period of rampant damp-heat, confirming its entry into the Spleen and Stomach to consolidate Middle Qi and resist external dampness invasion." Liu also discussed Spleen and Stomach together but believed it acts on the Stomach first and then the Spleen. Zhang Yinan focused solely on benefiting the Spleen without mentioning the Stomach. I ponder that the Stomach is Yangming Dry Metal, while the Spleen is Taiyin Damp Earth. The reason it is called Damp Earth is what Zhang Yinan meant by "Earth with dampness can irrigate the four directions," just as the earth generates all things only after receiving rain and dew. Baizhu is sweet in taste and rich in mucilage, resembling damp Earth; how could it not be the principal herb for the Spleen? Its flesh is white, turning slightly red when old, and its taste carries acridity, enabling it to travel from the Spleen to the Stomach and reach the muscle surface.

Baizhu eliminates Spleen dampness and consolidates Middle Qi, serving as a pillar in midstream. To disperse exterior pathogens, it cannot penetrate from muscles to skin/hair unless assisted by herbs like Mahuang (Herba Ephedrae), Guizhi (Ramulus Cinnamomi), or Fuzi (Radix Aconiti Lateralis Preparata). This is likely because its strong and sweet flavor excels in maintaining stability. Mahuang, Guizhi, and Fuzi are agents that scatter wind-cold; adding Baizhu to remove dampness creates formulas for treating Wind-Damp and Cold-Damp. Without dampness, Baizhu is not added; thus, Mahuang, Guizhi, and Fuzi are mostly used for Taiyang disease in *Shanghan*, whereas Baizhu is used only when there is water qi. Zou stated, "In Zhang Zhongjing's formulas for treating Bi syndrome caused by wind-cold-damp, many do not use Baizhu, as Baizhu is most suitable for cases dominated by wind or damp, but less effective for those dominated by cold." Generally, wind dominance causes vexation, and damp dominance causes heaviness. In the formulas in *Jinkui Yaolue* treating Bi with Baizhu, there is either vexation or heaviness. Some mention body vexation and pain, some body pain and vexation, some joint vexation and pulling pain, some abdominal heaviness, some head heaviness, or neither vexation nor heaviness but only body pain, cold hands and feet, and joint pain. This separates wind, damp, and cold into three categories. However, one must not overlook that when Zhongjing mentions "vexation," damp may be present; when he mentions "heaviness," wind may be present; when he mentions "cold," both wind and damp may be present. Comparing this with *Ben Jing*'s indication for wind-cold-damp Bi, everything matches perfectly. Zou merely stuck to literal meanings without careful examination, thereby misunderstanding the properties and uses of Baizhu entirely.

Whenever Zhang Zhongjing uses Guizhi up to four liang, it is invariably to promote urination and drain kidney pathogens. *Guizhi Fuzi Qugui Ji Baizhu Tang* explicitly states: if stool is hard and urination is normal, remove Guizhi; if stool is not hard and urination is difficult, add Guizhi. This undoubtedly proves Guizhi's ability to promote urination. However, You Shi interpreted this formula saying: "Hard stool and normal urination indicate that although exterior Yang is weak, interior Qi functions autonomously. Therefore, dampness in the skin should be driven inward so water exits via the urinary tract, rather than being expelled outward to endanger the weakened Yang. Thus, Guizhi's pungent dispersal is removed, and Baizhu's bitter dryness is added, combined with the powerful movement of Fuzi, to jointly attack the skin and drive out water qi." If Guizhi is removed because urination is already free, why still aim to drive dampness out through the urinary tract? Furthermore, if one says it should be driven inward and not outward, yet claims adding Baizhu and Fuzi attacks the skin to drive out water, isn't that still expelling it outward? This shows You Shi completely failed to grasp the meaning of the text. Zou's interpretation is slightly better but still flawed. He explained removing Guizhi and adding Baizhu as: "When the Spleen is healthy, it controls water; water inside flows to the Bladder making stool solid, water outside returns to the Stomach making stool moist." Claiming Baizhu makes internal water flow to the Bladder is incorrect; Zhongjing adds Baizhu precisely because it does not promote urination. Claiming external water returns to the Stomach implies reinforcing Earth due to hard stool, a logic that is obscure and merely speculative. According to Zhongjing: "After taking three doses, the patient feels dizzy; do not be alarmed. This is because Baizhu and Fuzi move together in the skin, driving out water qi which has not yet been fully eliminated." This confirms that Baizhu and Fuzi work together to expel water via the exterior, not the interior, proving water does not return to the Stomach. Someone might ask, what about hard stool? The answer is: frequent urination leads to hard stool. Here, "normal urination" means frequent urination. Water滞留 in the skin should not stay, and water in the reservoir should stay but doesn't; the Spleen fails in its duty, and the transmission of the intestines and Bladder is disrupted. Removing Guizhi and adding Baizhu regulates urination so existing fluids are not lost, and as Spleen function recovers, new fluids are generated; with external dampness removed and internal fluids steaming, who says adding Baizhu is insufficient to moisten the stool?

*Daming Bencao* records Baizhu treating regurgitation and promoting urination; *Jiegu Bencao* records it generating fluids and stopping thirst. These are likely errors resulting from failing to understand Zhongjing's formulas properly. *Wuling San* consists of only five ingredients interacting with profound principles. Pulse floating and fever are exterior signs; vexation, thirst, and dysuria are interior signs. Taiyang exterior pathogen transforming into heat transmits to the interior, causing thirst and drinking, leading to water accumulation and failure to transform, hence dysuria. For releasing the exterior, only Guizhi is used; for treating the interior, only diuresis is employed without clearing heat. Using four ingredients for diuresis might increase dryness and heat. One must know that since the exterior is not fully resolved, it belongs to Yang containing Yin, unlike Yangming disease where cold herbs can be freely used. Water is a Yin pathogen, requiring Pungent, Sweet, and Warm herbs to transform. Although Guizhi is not primarily for diuresis, Qi transformation relies on it. Zhu Ling and Fu Ling are also Taiyang herbs; cooperating with Guizhi, they promote diuresis and release the exterior. The dosages of all five ingredients are small, taken as powder, with instructions to drink warm water to induce sweating—a comprehensive approach. Yet, the method for treating the interior is embedded within. Guizhi is used minimally to reach the exterior; Ze Xie is used maximally for its salty descent; Baizhu is used to benefit Middle Qi, collect water dampness, and stabilize upper and lower. Then the exterior is resolved, and water moves. Once the exterior is resolved and water moves, heat withdraws, and thirst stops. To claim Baizhu stops thirst and promotes urition is to misunderstand its strengths. *Fuling Zexie Tang* treats gastric regurgitation with thirst for water. Gastric regurgitation indicates Spleen injury failing to grind, accompanied by fluid retention; thus Baizhu is used to strengthen the Spleen and overcome water, not to stop regurgitation. Shengjiang and Banxia are specific for vomiting; the formula has Shengjiang but no Banxia because Banxia is contraindicated in thirst. Baizhu is sweet and mucilaginous, originally capable of generating fluids, as seen in *Guizhi Fuzi Qugui Ji Baizhu Tang* treating hard stool. However, its nature is drying; in cases with dampness, it indeed enables Spleen transport and fluid generation. But in Yin deficiency with fluid exhaustion, relying on Baizhu would be ineffective.

The addition or removal of Baizhu appears frequently in Lizhong Wan. To understand its usage, look here, and you will have grasped more than half. The text states: "Sensation of pounding above the navel indicates Kidney Qi moving. Remove Baizhu, add four liang of Guizhi." Kidney Qi moving is a precursor to Ben Tun (running piglet). Using Guizhi to descend and drain is an established method found in both *Shanghan Lun* and *Jinkui Yaolue*. Adding Guizhi is fine, but why remove Baizhu? Earth controls Water, so *Qianjin Fang* uses Baizhu to treat marrow overflow; such a case seems to suit reinforcing Earth. However, Baizhu can restrain but not drain. If Baizhu is not removed, it obstructs the middle, hindering Guizhi's action; hence, Guizhi requires removing Baizhu. The text states: "For excessive vomiting, remove Baizhu and add two liang of Shengjiang; for excessive diarrhea, use Baizhu again." *Zhuling Tang*, *Wuling San*, and *Fuling Zexie Tang* all treat vomiting without removing Baizhu. *Shengjiang Xiexin Tang*, *Huangqin Tang*, *Sini Tang*, and *Baitong Tang* all treat diarrhea without using Baizhu. Why is this different? This refers to Cold Huoluan. In excessive vomiting, vomiting exceeds diarrhea; in excessive diarrhea, diarrhea exceeds vomiting. When vomiting exceeds diarrhea, interior dampness is light but Stomach rebellion is severe; adding Shengjiang disperses with pungency, and removing Baizhu avoids its cloying sweetness. When diarrhea exceeds vomiting, Spleen dampness is heavy; strengthening the Spleen and removing dampness requires Baizhu. Hence, remove for vomiting, use for diarrhea. The text states: "For thirst desiring water, add Baizhu to make four liang and half." Baizhu is not for treating thirst. Why add it instead of removing it? *Lizhong Tang* warms the Middle to treat Huoluan with cold and aversion to water. Thirst desiring water here is not due to dry-heat, but due to loss of fluids from severe vomiting/diarrhea and weak Spleen. Although Renshen generates fluids via Qi, Baizhu generates fluids via Taste. Reinforcing Middle Earth and nourishing the source of transformation is particularly effective, hence Baizhu is added instead of Renshen. The text states: "For abdominal fullness, remove Baizhu and add one piece of Fuzi." Huixi attributes this to Yang deficiency; You Shi to Qi stagnation; Zou to Spleen excess. The syndrome is Spleen Cold; *Jinkui* has texts stating abdominal fullness is Cold. Adding Fuzi confirms Yang deficiency. If it were Spleen Excess, one would use Houpo Qi Wu Tang, Da Chaihu Tang, or Da Chengqi Tang, which are vastly different. *Sini Tang* warms the Kidney with Jiang and Fu; this warms the Spleen with Jiang and Fu. Kidney Cold/Yang deficiency invades the Spleen, so Jiang assists Fu. Spleen Cold/Yang deficiency originates from the Kidney, so Fu assists Jiang. Baizhu must be removed.

*Bielu* states Baizhu removes urgency and fullness below the heart; this must be read together with eliminating phlegm-fluids. However, Baizhu cannot act alone and is suitable only for Middle Deficiency. *Jinkui* states: "For phlegm-fluid diseases, harmonize with warm herbs." *Ling Gui Zhu Gan Tang* succeeds through the cooperation of all four ingredients; none can be omitted. In *Shanghan*, Fu Ling is increased by one liang to urgently drain water, and Baizhu is decreased by one liang to slightly reduce congestion, due to Qi rushing. Moreover, Baizhu is not necessarily used for tonifying deficiency after purging/vomiting. *Guizhi Renshen Tang* treats epigastric hardness/fullness; Baizhu is used because after multiple purgations, diarrhea persists and deficiency is severe. Only in *Guizhi Qugui Ji Fuling Baizhu Tang*, where exterior signs remain but Guizhi is removed, and epigastric fullness/pain leads to adding Baizhu, is it puzzling. However, after taking Guizhi Tang or purging, even if not precise, pathogenic Qi has weakened. Head/neck stiffness, slight fever, but pulse not floating, no aversion to cold/wind—this slight fever indicates slight opening/closing, distinct from typical headache/fever. The key is water stopping in the heart region causing fullness/mild pain, no sweat, and dysuria, leaving no exit for pathogens. Taiyang is the mansion of Cold Water; the vertex is where Taiyang meridians arrive. If not for water stopping in the heart, previous Guizhi Tang would have relieved stiffness. The persistence is partly due to Cold Water not descending. Guizhi is contraindicated without sweat and unnecessary for exterior treatment here, so it is removed. Fu Ling is首选 for promoting urination, so it is added. Water stops due to insufficient Yang Qi; without boosting Qi, the pathology won't turn. Baizhu boosts Qi and removes dampness, so it is added. Although cloying Baizhu is unsuitable for fullness/pain, its efficacy relies on Shaoyao to astringe it. Baizhu is the specific herb for the Spleen; with Shaoyao it enters the Spleen quickly; with Fu Ling it cooperates to drain water. As water moves, fullness/pain resolves, and Taiyang's mild pathogen won't remain on the exterior. Gan Cao is the assistant for Baizhu's tonification. Jiang and Zao harmonize Ying and Wei, leaving no room for pathogens.

*Bielu* states Baizhu treats severe wind on the body and face; this "wind" refers to Haizang's concept of Baizhu tonifying Liver Wind Deficiency. Liu stated: "Yang deficiency with Yin accumulation, prolonged Yin fails to transform, causing Yang to transform into Wind, called Wind Deficiency." Also: "Yang accumulating in Yin causes Qi deficiency; Qi deficiency generates dampness." Thus, Baizhu's treatment of wind still revolves around dampness. The efficacious *Zhufu Tang* nearby in *Jinkui* treats Wind Deficiency syndromes. *Bielu* also treats wind vertigo, headache, and tearing, followed by eliminating phlegm-fluids, implying wind vertigo stems from phlegm-fluids; eliminating phlegm-fluids treats wind vertigo. Zou argued that damp, water, and fluid share one source but three branches, citing *Jinkui* formulas for vertigo, damp, and water to prove this, and stating *Ben Jing*'s "stop sweating and relieve heat" applies mostly to Wind-Damp combusting, such as *Wuling San*, *Fangji Huangqi Tang*, and *Gancao Fuzi Tang*, which are verified treatments, but cannot be used for heat-induced sweating and fever. This is indeed accurate. However, he was puzzled by a case in *Jinkui*: *Xiao Banxia Ji Fuling Tang* treats fluid vertigo without Baizhu due to epigastric stuffiness. *Xiao Banxia Tang* treats vomiting; with only three ingredients, naming it *Xiao Banxia Ji Fuling Tang* clarifies the treatment aims to stop vomiting and promote urination. Although vomiting due to fluid between the diaphragm, and vertigo/palpitations from such fluid, are indications for Baizhu, even epigastric stuffiness caused by hunger does not strictly contraindicate Baizhu. Yet, absolutely excluding Baizhu is inexplicable. After careful thought, I found the reason: Zhongjing's word choice is precise. Vomiting described as "acute/sudden" (*cu*) cannot be ignored. Acute vomiting implies no pre-existing fluid in the diaphragm, possibly due to temporary relaxation of Clear Yang, causing fluid retention and failure to transform, leading to Stomach rebellion and vomiting. The Spleen is intact, not deficient. Ginger and Banxia ascend Yang and descend rebellion above; Fu Ling drains water below; this is sufficient. Adding cloying Baizhu across the diaphragm would be harmful, not helpful. *Zhishi Xiebai Guizhi Tang* treats Chest Bi, stating *Renshen Tang* also treats it. One syndrome, differing in deficiency/excess, with opposing attacking/tonifying drugs; the appropriateness of Baizhu is clearly visible.