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Poria (Fuling): Its flavor and qi are both extremely light, and its nature is neutral. It is good at regulating the Spleen and Stomach because the Spleen and Stomach belong to Earth, and the flavor of Earth is originally light (the principle of why Earth's flavor is light was discussed in detail by Xu Lingtai). Therefore, the *Neijing* states that the light flavor returns to the Stomach, and the *Shenrou Wushu*, elaborating on the purport of the *Neijing*, also states that a light flavor can nourish Yin of the Spleen. This is likely because its property can transform phlegm-fluids in the Stomach into fluid substances, guide them to transport to the Spleen and reach the Lung, and then descend along the Sanjiao waterways to return to the Bladder, making it the principal herb for leaching out dampness and draining phlegm. However, its nature is purely benign; it contains tonification within its draining action. Although it is a product of leaching and promoting urination, it actually can cultivate Earth to generate Metal, benefiting the Spleen, Stomach, and Lung. Moreover, because it absorbs the residual Qi of pine roots and lies hidden underground without sprouting shoots outward, it is also good at consolidating the floating and dispersing Qi of the Heart to calm the Soul and stabilize the Spirit. It simultaneously drains fluid-phlegm below the Heart to eliminate palpitations and fright, serving as an important herb for the Heart Meridian. Furthermore, its property of lying hidden can also consolidate and suppress the external-dispersing fluid-Qi, turning it downward, preventing it from transforming into sweat and emerging, acting as an important herb for stopping sweating. The part growing while embracing the root is called Poria with Hostwood (Fushen), which has stronger power in nourishing the Heart than Poria (Fuling). If Poria (Fuling) is used in decoction, when cut into blocks, it cannot penetrate even after boiling all day; it must be sliced thinly or pounded into powder to fully extract its efficacy.

[Appendix] My friend Zhu XX said: "A family surnamed Wu in Sheng County made a living by cultivating Poria (Fuling). In spring, the daughter-in-law of the Wu family fell ill. It had been more than a month since her postpartum period. She suffered from high fever, thirst but no desire to drink, incessant sweating, palpitations, and insomnia. I was invited to treat her. Her face appeared red, and her pulse showed a slippery quality. I urgently prescribed a decoction of Licorice Root (Gancao), Ophiopogon Tuber (Maidong), Bamboo Leaf (Zhuye), Biota Seed (Baiziren), Floating Wheat (Fuxiaomai), and Jujube Date (Dazao), but it was ineffective. Subsequently, I used Suanzaoren Tang, removing Ligusticum Rhizome (Chuanxiong) and adding Floating Wheat (Fuxiaomai) and Jujube Date (Dazao), which was also ineffective. Then I used Guipi Tang plus Dragon Bone (Longgu), Oyster Shell (Muli), and Cornus Fruit (Yurou), yet the condition remained unchanged. At this time, I was at my wit's end. Suddenly, someone stepped forward and said, 'Why not use tonic herbs to缓 (slow/relax) it?' I thought this was nonsense; the so-called tonic herbs indicated a lack of insight in the heart. I merely responded casually. It was already time for evening rest. The next morning upon waking, the patient's father-in-law rushed to tell me, 'My daughter-in-law's illness was cured last night using tonic herbs.' I was skeptical and did not know what the so-called tonic herb was. The father-in-law brought the dregs to see me. In the bowl were four or five taels of Poria (Fuling). Alas! It was Poria (Fuling); why call it a tonic herb? I could not speak for half a day. Sitting upright and pondering, I realized that any disease with a thread of vitality can be treated. Poria (Fuling) is indeed an important herb for treating palpitations and the main herb for treating sweating. Zhang Zhongjing treated Taiyang disease with sweating and thirst using Wuling San; if there was no thirst, he used Fuling Gancao Tang. For Taiyang disease with cold extremities and palpitations below the Heart, one should first treat the water retention and administer Fuling Gancao Tang. It can be known that palpitations arise from excessive sweating leading to internal depletion of Heart fluids; when Kidney Water rises to rescue the Heart, palpitations occur. Other herbs cannot treat water retention, so Poria (Fuling) is used to pacify it. In this case, the insomnia stems from palpitations, and the palpitations stem from sweating. The high fever, thirst without desire to drink, and slippery pulse all present signs of fluid-Qi. Fortunately, we encountered a family that cultivates Poria (Fuling); otherwise, incessant sweating would eventually lead to collapse of Yang, and fluid-Qi overwhelming the Heart would extinguish Fire. Whose fault is this? I accepted the blame and withdrew." Observing Zhu XX's discussion, he did not hesitate to expose his own failure to speak for the medical community. In his explanation of the classics, he clearly brought out the profound meaning behind Zhang Zhongjing's use of Poria (Fuling). This demonstrates not only his precision in analyzing principles but also his sincere intention.

Cui XX from Tianmen County, Hubei Province, wrote a letter stating: In 1930, a woman surnamed Li suffered from dizziness and vertigo of the head and eyes, palpitations (Zhongchong), vomiting of saliva and froth, and occasionally felt Qi rushing upward, leading to stupor and loss of consciousness. Other doctors treated her with sedative herbs without effect. Subsequently, over ten other doctors were consulted, and none of the prescriptions worked; the danger reached an extreme point. Upon examining her pulse, I found it floating and weak. Observing her physical state, I felt it difficult to prescribe medication. Suddenly, I recalled the method of heavily using Poria (Fuling) discussed in the "Explanation of Poria" section of *Yixue Zhongzhong Canxi Lu*. I believed this might save the case. Thus, I instructed her to take a decoction of single-ingredient Poria (Fuling), one liang. Five minutes after ingestion, the symptoms alleviated. Immediately, the dregs were decocted and taken again, resulting in enhanced clarity of spirit and freshness. After taking several doses, the illness was completely cured. Since then, whenever encountering similar cases, administering this formula has always been effective.