Library

Cinnamon Bark (Rougui): It has a pungent and sweet taste, an aromatic odor that is penetrating and dispersing, and a very hot nature, belonging to pure Yang. Since it is the bark from the lower part of the tree trunk near the roots, its action tends to descend, warming the Dantian (lower abdomen/Energy center), strengthening the Primordial Yang, and supplementing the Ministerial Fire (Fire of the Mingmen in the Kidneys). Its purple-red color enables it to assist the Sovereign Fire (Heart Fire), warm and unblock the blood vessels, and treat bi-syndrome (obstruction causing pain) of the whole body's blood vessels due to cold. Therefore, it treats pain in joints, waist, and limbs, as well as Baiju (a type of yin-cold abscess) in patients with sores. Wood withers when encountering Cinnamon Twig; furthermore, since its pungent taste corresponds to Metal, it is good at pacifying Liver Wood, treating excessive anger caused by rebellious Liver Qi. If there is heat in the Liver, it can be assisted by herbs such as Gentian Root (Longdancao) and White Peony Root (Shaoyao). The *Shennong Bencao Jing* states that it acts as the vanguard messenger for various medicines, likely because its aromatic and penetrating qi reaches internally to the zang-fu organs, tendons, and bones, and externally to the meridians and interstices, pervading the entire body in an instant. Thus, in places where other medicines cannot penetrate, with the guidance of Cinnamon Bark, nothing remains unpenetrated.

Note: Aconite Root (Fuzi) and Cinnamon Bark (Rougui) both have pungent and hot flavors and odors, capable of supplementing the Primordial Yang. However, when the Primordial Yang is on the verge of exhaustion or floating away into collapse, Aconite Root should be used rather than Cinnamon Bark. This is indeed because Aconite Root has only a strong flavor, whereas Cinnamon Bark has both strong flavor and odor; within its tonifying action, it actually possesses dispersing power. It is not a major medicine for rescuing critical conditions and reversing dire situations. Observing the formulas for Shaoyin disease (Lesser Yin Disease) in Zhang Zhongjing's *Treatise on Cold Damage Diseases* (*Shanghan Lun*), which use Aconite Root but not Cinnamon Bark, confirms this.

Cinnamon Bark has extremely strong flavor and odor, and long decoction is strictly contraindicated. In the market, it is often ground into fine powder; after just a few boils, its medicinal power diminishes, let alone boiling for dozens of times. Conversely, Gypsum Fibrosum (Shigao) has very faint flavor and odor, and being a mineral substance, its medicinal power will not be released unless it is ground fine and decocted. However, in the market, it is often not ground fine. Therefore, when I use Gypsum Fibrosum, I must grind it into fine powder before decocting. When using Cinnamon Bark, one should merely remove the rough bark and add the whole piece to the decoction. Other materials similar to Cinnamon Bark or Gypsum Fibrosum can follow these examples.

Cinnamon Bark tastes spicy and sweet; those where sweetness surpasses spiciness are superior, while those where spiciness surpasses sweetness are inferior. Generally, they are all barks taken from vigorously growing trees, thus containing oiliness, making them suitable for medicinal use, regardless of thickness. If the taste is neither particularly sweet nor spicy, and the bark is very dry and withered, it is bark from a dead tree and should not be used.