See original post: Tongue Diagnosis and Visual Diagnosis in Chinese Medicine
Tongue examination provides some of the most important data for pattern identification. The tongue objectively reflects the state of qi and blood, progression and regression of disease, the degree of heat and cold, and the depth of the penetration of evils. Changes in the appearance of the tongue are particularly pronounced in externally contracted febrile diseases and disorders of the stomach and spleen. The ancient Chinese said: "The tongue is the shoot of the heart," and "the tongue is the external indicator of the stomach and spleen."
However, in clinical practice, serious illnesses are not necessarily reflected in major changes in the appearance of the tongue. Moreover, normal healthy individuals may show abnormal changes in the appearance of the tongue. Therefore, the data provided by the tongue examination must be carefully weighed against other signs and symptoms, the pulse, and the patient's history before an accurate diagnosis can be made.
The go on to describe (1) inspecting the form of the tongue; describing enlargement, shrinkage, red spots, fissures, and smoothness, (2) inspecting the bearing of the tongue; describing stiffness, limpness, trembling, deviation, contraction, and "worrying", (3) inspecting the color of the tongue; describing pale, red, crimson, and purple, (4) relationship between sections of the tongue surface and the organs, (5) inspecting the nature of the tongue fur; describing moistness, thickness, clean, slimy, grimy, and peeling, and (6) inspecting the fur color; describing white, yellow, and black.
Maciocia describes in Tongue Diagnosis in Chinese Medicine according to the Eight Principles. The Eight Principles theory is a fundamental expansion of yin/yang theory in Chinese medicine. He goes on to describe (1) the tongue spirit and body color; including pale, red, dark red, purple, blue, white vesicles, and the underside of the tongue, (2) the tongue body shape; including thin, swollen, partially swollen, stiff, flaccid, long, short, cracked, loose, deviated, numb, moving, quivering, rolled, tooth-marked, ulcerated, and sore-covered, and (3) tongue coating; including distribution, thick, thin, dry, wet, white, yellow, gray, and black. (Maciocia also covers tongue diagnosis in Diagnosis in Chinese Medicine.)
The Eight Principles of Yin & Yang:
Yin Interior Cold Deficiency
Yang Exterior Heat Excess
Kirschbaum organized Atlas of Chinese Tongue Diagnosis (Volume 1) largely by organ associations and major pathologies: (1) pale tongue signs, (2) tongue signs associated with kidney disharmonies, (3) tongue signs associated with stomach and spleen disharmonies, (4) tongue signs associated with lung disharmonies, tongue signs associated with disharmonies of the heart, (5) tongue signs associated with liver disharmonies, (6) tongue signs associated with blood stasis, (7) tongue signs associated with heat disorders, and (8) tongue coating.
So, there are different ways to approach and discuss the two main factors of tongue diagnosis: body and moss. As with other forms of diagnosis in Chinese herbal medicine, the basics are quite simple while the complexity is infinite. Of course, it will be a lot to begin learning even the relatively few points about the color, moss, and other qualities of the tongue. However, once you become more familiar it is really quite simple. (Remember, when discussing pulse we brought up the idea that mastery begins with mastering the basics. In this case it is in memorizing the terms. But, we have already discussed that red means heat, purple means blood stagnation... thick build-up means damp, dry means dry... To those that have studied other forms of traditional diagnosis, the principles of tongue diagnosis should come quite naturally.)
Natural medicine is based on understanding the condition of the chi, blood, fluids, organs, mind, and spirit. If we consider this related to the tongue, it is all reflected there. The chi gives the tongue form. Blood gives the tongue color and nourished the tissue and the moss. The fluids fill the tongue and rise to the surface (like steam), creating the moss. The organs, energy channels, and non-physical aspects of the person are reflected in their tongue.