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There is a significant difference between the true fading and true transformation of tongue coating, and its peeling or sudden disappearance. True fading must occur through transformation. What is meant by transformational fading? It refers to the tongue coating gradually becoming thinner from being thick, and becoming loose from being compact, with breaks appearing in the middle, scattering and separating without continuity; all these are adverse signs. These conditions arise because of the misuse of purgative and digestive agents, or the misuse of diaphoretic methods, which damage both Stomach Qi (Stomach energy) and Stomach Yin (Stomach fluids), thus producing such manifestations.

In dampness patterns, the tongue is moist; in heat patterns, the tongue is dry; this is the general rule. However, there are cases where damp-evil enters the Qi level, and Qi fails to transform fluids, resulting in dryness; or heat-evil enters the Blood level, resulting in a moist tongue. One must carefully examine the pulse and integrate the findings for judgment.

Thick, greasy, and putrid tongue coatings do not indicate cold patterns. This is due to Stomach Yang steaming upward and turbid qi reaching the surface, causing the coating to be thick and putrid. It is contraindicated to use warming, drying, and resolving agents, and especially contraindicated to use diaphoretics. Clearing and descending methods should be employed. If treated incorrectly, the coating will inevitably turn grayish-dark; one must reflect deeply on this error.

Thick, greasy, and putrid coatings differ from merely thick and greasy ones. Putrid coating resembles rotting dregs or rotten tendons, piled up like tofu; its edges are thick, indicating excess Yang, which can stir up putrid turbid qi from the Stomach to rise, hence this appearance. In contrast, a thick and greasy coating is slightly thicker in the center but thinner at the edges, lacking pores and granules, resembling a surface scraped smooth by a polished object. This is called thick and greasy coating, indicating that Yang Qi is suppressed by Yin evil. It implies pathogenic factors such as damp-turbidity, phlegm-fluid retention, food stagnation, blood stasis, or stubborn phlegm, requiring resolving and transforming methods. One case involves excess Yang, while the other involves suppressed Yang; a slight deviation leads to a great error. Can one not be cautious? Many people today mistakenly confuse the term "greasy," so this distinction is specifically discussed to differentiate them.

"Short tongue" refers to the inability to extend the tongue fully, belonging to deficiency patterns. A short tongue accompanied by retraction of the scrotum belongs to heat patterns. A short tongue without scrotal retraction belongs to deficiency patterns. "Stiff tongue" refers to the inability to move freely, resulting in unclear speech. This indicates damage to the function of the brain and nerves. One must investigate the cause; once the cause is identified, treatment methods can be determined.

Black coating on the tongue may progress from white to yellow, and then to black; this is a favorable pattern (Shun). Alternatively, it may progress from white to gray, and then to black, without passing through yellow; this is called black sunken coating, an unfavorable pattern (Ni). This often results from the prolonged misuse of warming and drying herbs, making it difficult to rescue. There are also cases of slow pulse with black coating, indicating insufficiency of Kidney Mingmen (Gate of Vitality); careful differentiation is required to distinguish true from false. A true black coating cannot be scraped off, allowing diagnosis based on the black coating. When progressing from yellow to black, it represents Yangming Heat accumulation. If moistening and purging methods are applied correctly, the carbonized heat qi of the Stomach Fu organ can be expelled outward; thus, it is called a favorable pattern, removing any doubt.