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Oyster Shell (Muli) primarily treats palpitations or movements in the chest and abdomen, and secondarily treats frightfulness, mania, irritability, and restlessness.

Textual Research
In the syndrome of Guizhi Qu Shaoyao Jia Shuqi Longgu Muli Tang (Cinnamon Twig Decoction minus Peony plus Coix Seed, Dragon Bone, and Oyster Shell), the manifestations are: frightfulness, mania, tossing and turning with inability to find a comfortable position.
In the above formula, Oyster Shell is used in the amount of five liang.
In the Muli Tang (Oyster Shell Decoction), the syndrome description is incomplete. (See Mutual Examination).
In the above formula, Oyster Shell is used in the amount of four liang.
In the Muli Zexie San (Oyster Shell and Alisma Powder), the syndrome description is incomplete. (See Mutual Examination).
In the above formula, Oyster Shell and other herbs are used in equal proportions.
In the Chaihu Jianggui Tang (Bupleurum, Ginger, and Cinnamon Twig Decoction), the manifestation is: slight irritability.
In the above formula, Oyster Shell is used in the amount of three liang.
In the above formula, Oyster Shell is used in the amount of two liang, which also follows the pattern of four liang.
In the Chaihu Jia Longgu Muli Tang (Bupleurum Plus Dragon Bone and Oyster Shell Decoction), the manifestation is: irritability and fright.
In the above formula, Oyster Shell is used in the amount of one and a half liang. (See External Transmission).

Having observed these formulas comprehensively, it seems that Oyster Shell's treatment of frightfulness, mania, irritability, and restlessness is no different from that of Dragon Bone. After dedicating myself to this study for a long time, I came to realize that Oyster Shell specifically treats palpitations or movements in the chest and abdomen. Scholars should examine this carefully.

Mutual Examination
Oyster Shell, Coptis Rhizome (Huanglian), and Dragon Bone all treat irritability, but each has its specific indication. The disease at the Danzhong (Conception Vessel 17, located at the center of the chest) is indicated by Huanglian; the disease below the umbilicus is indicated by Longgu; whereas irritability in the chest and abdomen with undefined location is indicated by Muli.
The entry for Muli Tang mentions: malaria. The entry for Muli Zexie San mentions: water retention. The syndromes listed therein are likely incomplete. By analogy, for wheezing and urgency of breathing with palpitations in the chest, Muli Tang is indicated. For bodily edema, palpitations in the abdomen, thirst, and difficult urination, Muli Zexie San is indicated. Scholars should examine this carefully.

Product Examination
Oyster Shell: Those shells that have been aged for a long time are superior. My family currently uses those sourced from Yizhou. Those sold in the market are unsuitable for use.

Ancient books are valued by the world because they yield verifiable results when applied today. Even if an ancient work ranks alongside the *Classic of Poetry* and the *Book of Documents*, if its words contradict reality, it is not worth valuing.
Although Materia Medica texts have been transmitted for a long time, their interpretations are often far-fetched. Arguments are based on subjective speculation, and citations rely on immortals. Their words are clever and seem plausible. Thus, their theories may be logically consistent but detached from reality, wavering and contradictory, no different from Zhao Kuo discussing military strategy. Therefore, my late father, Dongdong Weng, wrote *Yao Zheng* (Verification of Medicinals), verifying efficacy through observation, correcting errors with rigorous standards, weighing appropriateness, and distinguishing similarities and differences with precision. Although he deeply explored the principles of classics, he never claimed omniscience as some Materia Medica scholars do. However, following the variations in application, the miraculous effects achieved seem almost divinely inspired. Such exquisite versatility belongs to the efficacy of the prescription, not to a single herb. Just as Yangsui (bronze mirror) extracts fire from the sun, and Fangzhu (stone bowl) collects dew from the moon, if clouds cover the light, fire and water cannot be obtained. Holding Yangsui all day fails to warm the hands; licking Fangzhu all night fails to quench thirst. Although Fangzhu and Yangsui can produce water and fire, blaming them for lacking inherent power when they fail under obstruction is incorrect; this is not natural ability. Natural ability comes from Heaven and requires no external aid. Efficacy is achieved through proper method and usage, which can serve as a basis. Ancient texts alone are not worthy of blind reverence. In *Yao Zheng*, indications are detailed and clear; it does not discuss Yin-Yang nor adhere rigidly to Five Elements. It relies on obvious symptoms, follows the methods of Changsha (Zhang Zhongjing), investigates the reality of efficacy, examines the state of affairs, and elucidates what others have not discovered, thereby illuminating those who wander blindly. This is indeed the legacy left by Bian Que.
After the book was completed, disciples revered it and repeatedly requested its publication. Father sighed happily and said, "Wrong! Why rush to publish? Many books published in the world are later discarded due to hasty decisions. Pharmacology is the foundation of medicine; investigating its excellence is a lifelong endeavor. Publishing uncorrected texts now to claim immortality would lead to ridicule. I would rather let them rot in the box than allow publication." Twelve years have passed since Father's passing. Now, I have commissioned the engraver to print and circulate it to the world.
On the first day of the eleventh month, winter of the year Jiachen during the Tenmei era, your son You respectfully inscribed.