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In the *Biography of Hua Tuo* in the *Records of Wei*, it is recorded that two government clerks, Er Xun and Li Yan, sought treatment together. Both suffered from headache and fever, experiencing identical distress. Hua Tuo stated: "Er Xun should be treated with purgation (Xia Fa), while Li Yan should be treated with diaphoresis (Fa Han)." Someone questioned this difference, to which Hua Tuo replied: "Er Xun has an exterior excess (Wai Shi), whereas Li Yan has an interior excess (Nei Shi); therefore, their treatments must differ." He administered different medicines to each, and by the next morning, both had recovered. I deeply suspect that Chen Shou mistakenly used the characters "interior" and "exterior" in his record, which does not reflect Hua Tuo's original intent.

If a patient presents with headache, fever, and aversion to cold, this indicates an exterior excess caused by Yin pathogenic factors; according to the principles, diaphoresis should be employed. If a patient presents with headache and fever, characterized only by a steaming sensation of heat without aversion to cold, this indicates an interior excess caused by Yang pathogenic factors; according to the principles, purgation should be employed. The term "exterior excess" refers to the exterior being Yang and representing the surface level. When Yang Qi is constrained by Cold pathogens and struggles at the surface, Yang becomes deficient while Yin prevails, resulting in symptoms of fever accompanied by aversion to cold. In such cases, diaphoresis can be used to disperse the pathogen and restore Yang Qi. The term "interior excess" refers to the interior being Yin and representing the deep level. Extreme Yin transforms into Yang; when Cold is severe, it generates Heat, causing Yang Qi to become excessive and penetrate inward. This results in interior excess in the Stomach Fu organ, manifesting as continuous steaming heat without aversion to cold. Here, purgation or draining methods can be used to restore Yin Qi. The "excess" mentioned here does not refer to the true fullness of healthy Qi, but rather to the excess of pathogenic factors. As stated in the *Su Wen*: "When pathogenic factors are vigorous, there is excess." Thus, I conclude that the terms "interior" and "exterior" in the biography of Hua Tuo contain errors.

In recent times, decoction powder (Zhu San) has been commonly prepared, while ancient liquid decoctions (Tang Ye) remain preserved but unused. This is likely because the dosages in ancient prescriptions, measured in *sheng* and *liang*, were often large, or the water volume was small leading to turbid, overly concentrated medicinal fluids. However, one fails to realize that the Sages specifically targeted single diseases, determining that one or two doses would yield results. Records indicating small water volumes are merely transcription errors, not the original intent of the ancients.

Since the An Lushan Rebellion in the Tang Dynasty, regional military governors became arrogant and unruly, continuing through the Five Dynasties period. With frequent warfare across the realm and difficult travel conditions, herbs and minerals from various regions rarely circulated. Consequently, physicians simplified their methods, converting decoctions into decoction powders. This led to many instances where treatments failed to address the disease accurately, causing confusion and frequent changes in prescription. This custom has persisted to the present day without reform, rendering ancient liquid decoctions practically useless books in the current era. Xu’s *Dahe Ji Yao Fang* from the Tang Dynasty reduced the *sheng* and *liang* measurements. While this adapted to popular practice, I feared the reduction was too drastic, causing the medicinal fluid to be exhausted before half the illness was cured, which concerned me. Through my own collection, organization, and deliberation over more than thirty years, I have gradually mastered these matters. Therefore, I dare to reduce the *sheng* and *liang* dosages, hoping to accommodate contemporary customs while facilitating clinical application. Some prescriptions may use half a dose, one-third, one-fourth, or one-fifth. Some increase water volume to prepare decoction powders, while others with severe conditions require specific liquid decoctions for aggressive treatment.

Some argue that ancient measurement units convert such that three ancient *sheng* equal one modern *sheng*, and three ancient *liang* equal one modern *liang*. This is incorrect. Ge Shi of the Jin Dynasty stated: "One Fuzi (Aconite Root) equals half a *liang*." He also said: "Use a cup instead of a *sheng*, and *fen* instead of *liang*." This indicates that ancient *sheng* and *liang* were consistent with modern ones, allowing people simply to reduce the dosage.

Most physicians today are ignorant and vulgar, content with mere subsistence, greedy for wealth. How could they possibly understand broad and comprehensive theories? They hoard shallow medical skills, preventing others from seeing their flaws, thereby boasting of their greatness. Relying on convenience, they claim divine skill, yet unfortunately, many die prematurely due to such negligence. There are few who are well-read and knowledgeable. Although some scholars occasionally appear, they all despise such practices. Unless one disregards worldly trends and is dedicated to saving lives, one cannot devote oneself to this study. Now, I explain previous statements, carefully correct omissions and errors, select sound arguments, delete cumbersome prescriptions, and add new insights without forced interpretations. I hope beginners can easily comprehend them; after reading this text, one should grasp seventy to eighty percent of the knowledge. These prescriptions were authored by ancient sages and are effective as if by magic. I do not list every name or source individually. Any personal insights or verified cases handled by myself are compiled in this volume for discerning readers to recognize.