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Having discussed the entries regarding tongue color, we now compile the entries regarding tongue coating. Tongue coating arises due to disease, and disease manifests through the coating. Observing only the tongue color without examining the coating makes it difficult to ultimately distinguish between deficiency and excess syndromes; observing only the coating without examining the color makes it impossible to measure the flourishing or declining state of the pathogen. Moreover, among the Hundred Diseases caused by the Three Causes (internal, external, and neither internal nor external), none lacks a tongue coating, and thus none cannot be verified through it. Is this not limited solely to *Shanghan* (Cold Damage)?

However, consulting ancient texts, only the *Shanghan* school has elaborated on this. They believe that in patients with *Shanghan*, if there is a tongue coating, it inevitably transitions from moist to dry, from slippery to rough, from white to yellow, from yellow to black, and even to scorched and cracked, or developing prickles. This indicates the pathogen transmitting inward, progressing from superficial to deep levels.

If the tongue presents with white foam or saliva, accompanied by stiffness and pain in the head and neck, this is *Taiyang Bing* (Taiyang Disease). If the entire tongue is covered with white flakes, accompanied by fever, eye pain, nasal dryness, and inability to lie down, this is *Yangming Bing* (Yangming Disease). If the tongue coating is white and slippery, accompanied by chest and hypochondriac pain and deafness, or alternating chills and fever, bitter taste in the mouth, dry throat, and dizziness, this is *Shaoyang Bing* (Shaoyang Disease). If there is a white coating on the tongue, hardness and fullness under the ribs, constipation, and vomiting, this is Yangming Disease combined with a *Chaihu Zheng* (Bupleurum Syndrome). If the white coating is dry and thick, accompanied by aversion to cold and body pain, it indicates the exterior syndrome has not yet resolved.

In patients with chronic dampness (*Shi Jia*), if purgatives are used prematurely, hiccups may occur, along with chest fullness, difficulty urinating, and a tongue appearing as if coated; this is because there is heat in the *Dantian* (Lower Jiao) and cold in the chest. Thirst for water but inability to drink leads to oral dryness and vexation. Vexation in the heart with a tongue coating indicates pathogenic factors lodging in the chest. A white coating on the tongue, vexation, rapid and forceful pulse, and constipation for six to seven days indicate that pus and blood will subsequently appear in the stool.

A white, wet, and thick tongue coating with slight fever, symptoms resembling *Jie Xiong* (Chest Binding), normal diet, frequent diarrhea, floating pulse at the Cun position, and small, fine, deep, and tight pulses at the Guan position is named *Zang Jie* (Organ Knotting). A smooth white coating on the tongue is difficult to treat. *Zang Jie* lacks Yang syndrome signs, has no alternating chills and fever, the patient appears quiet, and with a smooth tongue coating, it must not be treated with attack methods.

A coating turning from white to yellow indicates the pathogen is about to transmit inward. A black center with a white, smooth edge, aversion to cold, and weak pulse indicates interior and exterior deficiency-cold. Two gray-black lines in the center of the tongue coating, with symptoms involving the Three Yin channels (Taiyin, Shaoyin, Jueyin), indicates the pathogen has transmitted inward. In *Liang Gan* (Dual Infection) within one or two days, a black center with a white edge on the tongue is an untreatable condition. A white coating with the root entirely black, followed by a restless pulse after sweating, is a death sign.

Initially slightly yellow, then deeply yellow, and finally scorched yellow tongue coating, accompanied by fever, spontaneous sweating, aversion to heat rather than cold, indicates Yangming Disease, specifically *Wei Jia Shi* (Stomach House Excess/Intestinal Excess Heat Accumulation). Yellow coating on the tongue, double vertical stripes, continuous sweating on hands and feet (*Ji Ran Han Chu*), tidal fever, and delirium indicate *Zheng Yang Yangming* (True Yang Yangming). Dry yellow coating, constipation, tidal fever, delirium, and continuous sweating on hands and feet indicate excess-heat in the Stomach Fu organ. Abdominal fullness and pain upon pressure, yellow tongue, and prior lack of purgation require purgation, after which the yellow coating will disappear.

Yellow and slippery coating, yellow eyes, sweating only up to the neck, and difficulty urinating indicate the body will develop jaundice. Yellow coating with spots on the tongue, body pain, fever, and red cheeks indicate the body has developed macules. Coating like ginger-yellow or pine-pollen color, with moist and cold fluids, or abdominal pain with vomiting and diarrhea, indicates decline of Yang and failure of Earth (Spleen). Yellow coating with small black dots, abdominal fullness, and dry throat indicate transmission to Taiyin. Two black halos with a gray center, dry mouth and tongue, indicate transmission to Shaoyin. Black, dry, and short tongue coating, with vexation, fullness, and retraction of the scrotum, indicates transmission to Jueyin. Black and dry coating in the center of the tongue indicates transmission to Shaoyin with severe heat and fluid exhaustion.

Coating that is black but soft, moist, and slippery indicates Water overcoming Fire, a cold syndrome. Yellow-black coating with signs of insufficiency indicates great depletion of Yuan Qi (Original Qi). Scorched black center of the tongue with a lively red texture, constipation, tidal fever, delirium, and continuous sweating on hands and feet indicate pathogenic factors gathering in the Stomach, suitable for purgation. Black coating at the root with unobstructed throat is treatable; black coating at the root with obstructed throat is untreatable. Black coating at the root with blackness at the base of the tongue瓣 (papillae) is fatal and untreatable. Black coating on the tongue in *Liang Gan* within one or two days is a death sign. Blackness extending to the base, dull and lifeless gray, is a collapse sign.

In pregnancy complicated by heat, with yellow scorched coating and *Wei Jia Shi*, purging the excess stabilizes the fetus. These are the discussions on tongue coating in *Shanghan*; they should be observed in conjunction with clinical symptoms. Other conditions include: dry and rough coating like snow indicating Spleen heat; yellow-black coating with lower abdominal pain and free urination indicating blood stasis; white flakes like rice grains on the tongue of a newborn, severe cases affecting mouth and nose, caused by excessive grain qi in the womb, known as *E Kou* (Goose Mouth/Candidiasis). These are all entries regarding tongue coating.

I propose: Deep red tongue color indicates excess pathogen; pale red tongue color indicates deficiency of healthy Qi. Deep red tongue with thin, slippery coating indicates healthy Qi overcoming pathogen; pale red tongue with thick, rough coating indicates pathogen overcoming healthy Qi. Deep red and lustrous tongue with thick, dry, and rough coating indicates excess in both form/Qi and disease/Qi. Pale red and withered/dark tongue with thin, cold, and slippery coating indicates deficiency in both form/Qi and disease/Qi.

Predecessors focused solely on the coating; later learners should observe the color, refer to the Five Methods, and integrate the Four Diagnostic Techniques. Then, for any yellow, white, gray, or black coating, distinctions of cold, heat, deficiency, and excess can be made. Even miscellaneous diseases can be verified, not just *Shanghan*. The *Diamond Sutra* states: "The Tathagata often says, you Bhikkhus, know that my teaching is like a raft; the Dharma should be abandoned, let alone non-Dharma." Therefore, those learning this method should take its essence and discard its dross, maintaining certain principles in mind without rigid adherence to fixed forms. Only then might one approach the Way.