Library

Commonly known as Guan Gui (Official Cinnamon).
Acrid, sweet, warm, non-toxic.
The *Shennong Bencao Jing* (Divine Farmer's Materia Medica) states it treats a hundred diseases, nourishes the spirit, harmonizes the complexion, and acts as a pioneer messenger for various herbs. Long-term use causes the face to generate radiance, appearing charming and youthful like a child.

[Invention/Commentary] Tong Gui (Cylindrical Cinnamon Bark) is acrid but not hot, thin in texture and capable of dispersing, acting as a messenger for various herbs; thus, it is suitable for many diseases. The *Bencao Jing* mentions its ability to nourish the spirit and harmonize the complexion, possessing the efficacy of acrid-warmness without the hazard of "vigorous fire" (excessive yang hyperactivity), serving as the pioneer messenger for all drugs. Any ascending and diffusing herbs, or tonifying herbs, are suitable for its use. Long-term use generates radiance and maintains a youthful appearance because its substance is thin and nature is light, lacking the fierce and potent qi of Guixin (Cinnamon Heart), Rougui (Cinnamon Bark), and Mugui (Mulberry Cinnamon), which do not overpower true yin. The *Bielu* (Additional Records) records its treatment of heart pain, hypochondriac pain, and wind in the hypochondrium, warming meridians and unblocking blood vessels, stopping irritability and sweating, all illustrating the principle that thin substances promote diffusion and unblocking. The *Bencao Gangmu* (Compendium of Materia Medica) incorrectly grouped the statements from *Bielu* and Li Dongyuan (Zhang Yuansu) under Mugui. Generally, Mugui refers to the thicker parts of the cinnamon tree, with functions similar to Rougui, specifically moving qi stagnation in blood. Tong Gui specifically circulates in the chest and hypochondrium, being a key herb for distension and fullness. For cold pathogenic factors rejecting closure in the middle jiao, stomach qi obstruction, vomiting of sour fluids, cold phlegm and fluid retention, running piglet disease, static blood, wind-cold painful obstruction, and stagnation in the three jiao, Bo Gui (Thin Cinnamon) is appropriate, as strong flavors induce purging, while thin textures promote unblocking.

Acrid, sweet, slightly warm, non-toxic.
[Invention/Commentary] Mahuang (Ephedra Herb) disperses outward to dispel cold, penetrating the skin and hair, thus specializing in inducing sweating. Guizhi (Cinnamon Twig) moves upward to scatter exterior pathogens, penetrating Ying (Nutrient) and Wei (Defensive) levels, thus able to resolve muscle tension. Zhang Yuansu stated that for headache due to wind-cold, opening the cou li (pores), resolving muscle tension, inducing sweating, and removing wind-dampness from the skin are all treated by Guizhi. Li Shizhen placed it under Mugui, which is an error. Note: Zhang Zhongjing used Guizhi Tang (Cinnamon Twig Decoction) for treating wind-strike and releasing the exterior, yet also stated "no sweat, do not use Guizhi." What is the meaning? In Taiyang Wind-Strike, the pulse is floating on the superficial level and weak on the deep level; floating yang indicates spontaneous heat, weak yin indicates spontaneous sweating. With solid Wei and deficient Ying, fever and sweating occur; Guizhi Tang is the specific remedy. Furthermore, in Taiyang disease with fever and sweating, this indicates weak Ying and strong Wei; when yin is deficient, yang must encroach upon it, and Guizhi is used to induce sweating. This harmonizes Ying, causing Wei qi to naturally harmonize, leaving no room for wind pathogens, leading to resolution through sweating; it is not that Guizhi itself induces sweating. When there is excessive sweating, Guizhi Tang is used because combined with Shaoyao (Peony Root) to harmonize Ying and Wei, the pathogen leaves with sweat, and sweating stops; it is not that Guizhi itself stops sweating. The secular view that Guizhi cannot be used when there is no sweat in Shanghan (Cold Damage) is incorrect. Guizhi is acrid and sweet, dispersing and yang-natured; even when cold damages Ying and Blood, it is an indispensable herb. Neither Mahuang Tang (Ephedra Decoction) nor Gegen Tang (Kudzu Decoction) lacks it, but one cannot use Guizhi Tang because it contains Shaoyao, which is sour, cold, and astringent, prohibiting the constriction of the exterior cou li. Regarding Shanghan with absent chi pulse (radial artery at wrist), this indicates deficiency of middle jiao Ying qi unable to connect downward to Wei qi; thus, Yitang (Maltose) is added to Guizhi Tang. The formula takes the sweetness of agriculture/grain to enter the stomach, hence named Jianzhong Tang (Establish the Middle Decoction). Adding Huangqi (Astragalus Root) makes it Huangqi Jianzhong Tang. Borrowing exterior-releasing herbs as interior-tonics, it treats male xu lao (deficiency exhaustion) insufficiency. The *Qianjin Fang* (Essential Prescriptions Worth a Thousand Gold) replaces Huangqi with Danggui (Angelica Sinensis Root) in Huangqi Jianzhong Tang to create Neibu Jianzhong Tang, treating female postpartum xu lei (emaciation) insufficiency. This not only avoids the risk of residual pathogens lurking inside but also prevents the invasion of yang pathogens inward. Only those who thoroughly understand Zhang Zhongjing's subtle applications can appreciate this. Detailed analysis shows Guizhi is originally a herb entering the Blood aspect of the Hand-Shaoyin (Heart) meridian, but because it also travels along the Yangwei Vessel, and since all Shanghan pathogens transmit via the Yangwei Vessel, this formula is the primary prescription for the Taiyang stage. Ancients considered Guizhi Tang the specific medicine for wind damaging Wei qi in the Taiyang meridian, unsuitable for other meridians; however, in Zhang Zhongjing's examples of the Three Yin stages, whenever yin exhaustion returns to yang, it was utilized. Even in Jueyin Danggui Sini Tang (Angelica Frigid Extremities Decoction), it is fundamentally based on Guizhi Tang. Rougui (Cinnamon Bark) and Fuzi (Prepared Aconite Root) each possess five aspects and have their specific indications. Although Rougui primarily governs the lower yuan, it manages blood and qi throughout the interior and exterior. Guixin (Cinnamon Heart) specifically warms the zang-fu organs and Ying blood, but does not circulate in the meridians' qi aspect. Mugai (Mulberry Cinnamon) has an ascending nature, governing both exterior and interior deficiency-cold. Bo Gui (Thin Cinnamon) excels at reaching the chest and hypochondrium but cannot directly reach the lower jiao. Guizhi harmonizes Ying and Wei, dissipates wind pathogens, and avoids the disaster of excessive sweating damaging the exterior; it is truly a high-quality herb and deserves to be called the ancestor of decoctions. The *Bencao Jing*'s mention of Mugui refers jointly to Rougui and Guixin; its mention of Tong Gui refers jointly to Guizhi. Other types such as Bangui (Board Cinnamon) and Mugui (Wood Cinnamon) are only used as spices or food ingredients and are not included in decoctions.