（仍与伤寒温病相出入。）
舌之有苔，犹地之有苔。地之苔，湿气上泛而生，舌之苔脾胃津液上潮而生。故平人舌中，常有浮白苔
一层，或浮黄苔一层，夏月湿土司令，苔每较浓而微黄，但不满不板。其脾胃湿热素重者，往往终年有白
浓苔，或舌中灰黄，至有病时，脾胃津液为邪所郁，或因泻痢，脾胃气陷，舌反无苔，或比平昔较薄。（
尝诊寒湿误服凉剂，呃逆不止，身黄似疸，而舌净无苔，脉象右关独见沉细无力，此脾胃气陷之征也。凡
水气凌心，胃阳下陷，每忽变无苔，日久即变暗变紫矣。）其胃肾津液不足者，舌多赤而无苔，
或舌中有红路一条，或舌尖舌边多红点，此平人舌苔之大较也。（尝见平人舌心钱大一块光亮淡紫色，但常苦
梦遗，无他病也。）
若夫有病，则舌必见苔，病藏于中，苔显于外，确凿可凭，毫厘不爽，医家把握，首赖乎此，是
不可以不辨。
风寒为寒燥之邪，风温为温燥之邪。风寒初起在表，风
温首伤肺经气分，故舌多无苔，即有黄白苔，亦薄而滑，渐
次传里，与胃腑糟粕相为抟结，苔方由薄而浓，由白而黄，而黑而燥，其象皆板滞不宣。迨下后，苔始化腐，
腐者，宣松而不板实之象，由腐而退，渐生浮薄新苔一层，乃为病邪解尽。
其有初起白苔，即燥如白砂者，名曰砂苔。此温燥之邪过重，宜速下之，佐以甘凉救液。亦有苔至黑而
不燥者，或黄黑苔中，有一、二条白者，或舌前虽燥，舌根苔白浓者，皆夹湿夹痰饮之故，亦有苔虽黄黑，
浇薄而无地质者，胃阴虚故也。苔有地质与无地质，此虚实之一大关也。（尝见有舌根
白苔板浓，如水久泡形，而两边现红肉两点者，是下焦寒水盛结，真阳不宣也。）
湿为浊邪，兼证最多。风湿伤表，苔多滑白不浓；寒湿伤里，苔多腻白而浓。
暑温、湿温、温疫、温热皆湿土郁蒸之气。冬温，因阳不潜藏，亦湿土郁蒸之余气。数者皆从口鼻吸入
肺胃膜原，由里而发。春温为冬伤于寒，寒郁久而化热，寒燥之气，又能搏束津液水饮，伏于膜原，与热
混合，亦由里而发。暑湿晚发，名曰伏暑，因夏伤暑湿，伏于膜原，秋日凉燥之气，又从外搏遏在内之暑湿，
此由表邪引动里邪而发，暑湿疟疾，亦多由此。是伏邪、时邪皆由里发，即多夹湿，故初起，舌
上即有白苔，且浓而不薄，腻而不滑，或粗如积粉，或色兼淡黄；迨传胃化火，与糟粕相抟，方由白而黄而
黑而燥；其暑温、湿温之邪，多黄白混合，似黄似白，或黄腻，或灰黄，而皆不燥。此等舌苔，即有下证，
或大便不通不爽；宜熟大黄缓下之，以舌苔不燥，肠中必无燥粪，多似败酱汁，故不
宜猛下。此燥邪、湿邪、燥湿混合之邪舌苔之大较也。（上石芾南《医原》。）
舌者心之窍，凡病俱现于舌，能辨其色，证自显然。舌
尖主心，舌中主脾胃，舌边主肝胆，舌根主肾。假如津液如常，口不燥渴，虽或发热，尚属表证。若舌苔粗
白，渐浓而腻，是寒邪入胃，夹浊饮而欲化火也。此时已不辨滋味矣，宜用半夏、藿香。迨浓腻而转黄色，邪
已化火也，用半夏、黄芩。若热甚失治，则变黑色，胃火甚也，用石膏、半夏。或黑而燥裂，则去半夏，而纯
用石膏、知母、麦冬、花粉之属以润之。至浓苔渐退，而舌底红色者，火灼水亏也，用生地、沙参、麦冬、
石斛以养之，此表邪之传里者也。其有脾胃虚寒者，则舌白无苔而润，甚者连唇口面色俱痿白，此或
泄泻，或受湿，脾无火力，速宜党参、焦术、木香、茯苓、炙草、干姜、大枣以振之。虚甚欲脱者，加附子、
肉桂。若脾热者，舌中苔黄而薄，宜黄芩。心热者，舌尖必赤，甚者起芒刺，宜黄连、麦冬、竹卷心。肝
热者，舌边赤或芒刺，宜柴胡，黑山栀。其舌中苔浓而黄者，胃微热也，用石斛、
知母、花粉、麦冬之类。若舌中苔浓而黑燥者，胃大热也，必用石膏、知母；如连牙床唇口俱黑，则胃将蒸
烂矣，非石膏三、四两，生大黄一两，加粪金汁、人中黄，鲜生地汁、天冬麦冬汁，银花露大剂投之，不
能救也。此唯时疫发斑及伤寒症中多有之。尝治一独子，先后用石膏至十四斤余，而斑始透，病始退，此其
中全恃识力。再有舌黑而润泽者，此系肾虚，宜六味地黄汤。若满舌红紫色而无苔者，此名绛舌，
亦属肾虚，宜生地、熟地、天冬、麦冬等。更有病后绛舌，如镜发亮而光，或舌底嗌干而不饮冷，此肾水
亏极，宜大剂六味地黄汤投之，以救其津液，方不枯涸。（上江笔花《医镜》。）
苔因内热，致脾气闭滞不行，饮食津液停积于内，故苔见于外，若脾气不滞，则饮食运化，津液流通，
虽热甚，不
必有苔也。（吾每诊寒湿内盛者，往往舌不见苔，及服温散之剂，乃渐生白苔，转黄而病始愈矣。）舌青，
或青紫而冷滑者为寒证。青紫而焦燥。或胀大，或卷缩者，为热证。寒甚亦必卷缩，筋脉得寒而
收引也，然必不焦燥，凡舌强硬短缩，而神昏语乱者，不治。亦有痰病，而舌本硬缩，及神昏不语者，当
以形证色脉参之。热病，舌本烂，热不止者死。伤寒，阴阳易，舌出数寸者死。
（按∶此乃房劳复，非阴阳易也。上郭元峰《脉如》。）
舌面上出现苔垢，就像地面上生长青苔一样。地面的青苔，是湿气向上蒸腾而生的；舌苔则是脾胃的津液上潮而生成的。所以正常人的舌中，常有一层浮起的白苔，或一层浮起的黄苔。夏季湿土当令，舌苔往往比较浓密且微黄，但不会布满全舌且板滞不活。那些脾胃湿热素来较重的人，往往终年都有浓白的舌苔，或者舌中部呈现灰黄色。等到生病时，脾胃津液被邪气郁遏，或者因为腹泻痢疾导致脾胃气机下陷，舌面反而没有舌苔，或者比平时更薄。（我曾诊治一例寒湿证误服凉药，导致呃逆不止，身体发黄似黄疸，但舌面光洁无苔，脉象右关部独见沉细无力，这是脾胃气陷的表现。凡是水气凌心，胃阳下陷的情况，常常突然变为无苔，日久就会变成暗色或紫色。）那些胃肾津液不足的人，舌头多呈红色而无苔，或者舌中间有一条红纹，或者舌尖和舌边有很多红点，这是正常人舌苔的大致情况。（曾见过正常人舌中心有一块铜钱大小、光亮淡紫色的区域，只是经常苦于梦遗，没有其他疾病。）
如果已经患病，舌头上必定会出现舌苔。病邪藏于体内，舌苔显现在体外，确凿可信，毫厘不差，医生把握病情，首先依赖于此，因此不能不仔细辨别。
风寒属于寒燥之邪，风温属于温燥之邪。风寒初起在表，风温首先损伤肺经气分，所以舌头多无苔，即使有黄白苔，也是薄而滑润的。逐渐传入里部，与胃肠中的糟粕相互搏结，舌苔才由薄变浓，由白变黄，进而变黑变燥，其形态都表现为板滞而不宣通。等到使用攻下法之后，舌苔才开始化腐，“腐”是指松疏而不板实的样子，由腐退去，逐渐生出一层浮薄的新的舌苔，这才是病邪完全解除。
有的初起就是白苔，干燥得像白砂一样，名叫“砂苔”。这是温燥之邪过重，应当迅速攻下，并佐以甘凉药物救阴液。也有舌苔发黑但不干燥的，或者在黄黑苔中夹杂一两条白色的，或者舌前部虽然干燥，但舌根部舌苔白而浓密的，这都是夹杂湿气或痰饮的缘故。也有舌苔虽为黄黑色，但浇淋上去后稀薄而没有根基（地质）的，这是胃阴虚所致。舌苔有根基和无根基，这是虚实辨证的一大关键。（曾见到舌根白苔板厚浓密，像水泡久了的样子，而两边露出红肉两点，这是下焦寒水盛结，真阳不能宣通的表现。）
湿是浊邪，兼夹证候最多。风湿伤及体表，舌苔多滑白而不浓；寒湿伤及体内，舌苔多腻白而浓密。
暑温、湿温、温疫、温热都是湿土郁结蒸腾之气。冬温，是因为阳气不潜藏，也是湿土郁蒸之余气。这些邪气都是从口鼻吸入肺胃膜原，从体内向外发散。春温是因为冬季感受寒邪，寒邪郁久化热，寒燥之气又能束缚津液水饮，伏藏在膜原，与热混合，也是从体内向外发散。暑湿晚发，名叫“伏暑”，是因为夏季感受暑湿，伏藏在膜原，秋季凉燥之气又从外部遏制内部潜伏的暑湿，这是由表邪引动里邪而发作，暑湿疟疾也多由此引起。伏邪、时邪都是从体内发作，大多夹杂湿气，所以初起时，舌上就有白苔，而且浓密不薄，腻而不滑，或者粗糙如积粉，或者颜色兼带淡黄；等到传入胃中化火，与糟粕相搏结，才由白变黄、变黑、变燥；至于暑温、湿温的邪气，多为黄白混合，似黄似白，或者黄腻，或者灰黄，但都不干燥。这类舌苔，即使有可下的证候，或者大便不通畅不爽利，也宜用熟大黄缓缓攻下，因为舌苔不干燥，肠中必然没有燥屎，大便多像败酱汁，所以不宜猛攻。这就是燥邪、湿邪、燥湿混合之邪在舌苔上的大致区别。（以上引用石芾南《医原》。）
舌是心的窍道，所有病症都显现于舌，能辨别其颜色，证候自然明显。舌尖主心，舌中主脾胃，舌边主肝胆，舌根主肾。假如津液正常，口不燥渴，虽然发热，仍属表证。如果舌苔粗白，逐渐变浓变腻，这是寒邪入胃，夹杂浊饮想要化火。此时已经尝不出滋味了，宜用半夏、藿香。等到舌苔浓腻转为黄色，说明邪气已经化火，用半夏、黄芩。如果热势严重失治，则变为黑色，这是胃火炽盛，用石膏、半夏。如果黑而干燥裂开，则去掉半夏，纯用石膏、知母、麦冬、天花粉等药物来滋润。等到浓苔逐渐消退，而舌底呈现红色，这是火热灼烧导致水亏，用生地、沙参、麦冬、石斛来滋养，这是表邪传入体内的情况。如果有脾胃虚寒的人，则舌白无苔而湿润，严重的甚至嘴唇、口唇、面色都萎黄苍白，这可能是泄泻，或者受湿，脾脏缺乏火力，速宜用党参、炒白术、木香、茯苓、炙甘草、干姜、大枣来振奋阳气。虚损严重欲脱者，加附子、肉桂。如果是脾热，舌中苔黄而薄，宜用黄芩。心热者，舌尖必红，严重的起芒刺，宜用黄连、麦冬、竹卷心。肝热者，舌边红或有芒刺，宜用柴胡、黑山栀。舌中苔浓而黄的，是胃微热，用石斛、知母、天花粉、麦冬之类。如果舌中苔浓而黑燥，是胃大热，必须用石膏、知母；如果连牙龈床、嘴唇口角都变黑，那么胃即将被蒸烂，非要用石膏三、四两，生大黄一两，加上粪金汁、人中黄、鲜生地汁、天冬麦冬汁、银花露大剂量投服，不能挽救。这只有在时疫发斑及伤寒症中多有发生。曾治疗一个独生子，先后使用石膏达十四斤多，斑疹才透发，病才退去，这其中全靠见识和定力。再有舌黑而润泽的，这是肾虚，宜用六味地黄汤。如果满舌红紫色而无苔，这叫绛舌，也属肾虚，宜用地黄、熟地、天冬、麦冬等。更有病后出现绛舌，像镜子一样光亮，或者舌底咽喉干燥但不想喝冷水的，这是肾水亏损到了极点，宜大剂量投服六味地黄汤，以拯救津液，否则就会枯涸。（以上引用江笔花《医镜》。）
舌苔因内热，导致脾气闭滞不行，饮食津液停积在体内，所以舌苔显现于外，如果脾气不滞，则饮食运化，津液流通，即使热势很盛，也不一定有舌苔。（我每次诊治寒湿内盛的患者，往往舌不见苔，等到服用温散药剂后，才渐渐生出白苔，转黄后病才痊愈。）舌色青，或者青紫而冷滑的，属于寒证。青紫而焦燥，或者胀大，或者卷缩的，属于热证。寒邪极甚也会卷缩，因为筋脉受寒而收缩牵引，但一定不焦燥。凡是舌体强硬短缩，并且神志昏迷、言语错乱的，属于不治之症。也有痰病，导致舌本硬缩，以及神志昏迷不语的，应当结合形体症状、面色、脉象综合参详。热病，舌本腐烂，热势不止的，预后不良死亡。伤寒，阴阳易病，舌伸出数寸的，预后不良死亡。（按：这其实是房劳复，不是阴阳易。以上引用郭元峰《脉如》。）
(These situations are largely consistent with the differentiation principles of Shanghan [Cold Damage] and Wenbing [Warm Diseases].)
The presence of coating on the tongue is like moss growing on the ground. Ground moss arises from moisture rising upward; tongue coating is generated by the fluids of the Spleen and Stomach ascending to the surface. Therefore, in a healthy person, there is often a layer of floating white coating or a layer of floating yellow coating on the center of the tongue. In summer, when damp-earth Qi prevails, the coating tends to be thicker and slightly yellow, but it does not cover the entire tongue nor become rigid and stagnant. Those with a constitutional excess of damp-heat in the Spleen and Stomach often have thick white coating throughout the year, or grayish-yellow coating in the center of the tongue. When illness occurs, the fluids of the Spleen and Stomach may be constrained by pathogenic factors, or due to diarrhea and dysentery causing Spleen Qi to sink, the tongue may appear without coating, or thinner than usual. (I once treated a case where cold-dampness was mistakenly treated with cooling agents, resulting in persistent hiccups, jaundice-like yellowing of the body, yet the tongue was clean without coating. The pulse at the right Guan position was exclusively deep, fine, and weak, indicating Sinking of Spleen Qi. Whenever Water-Qi assaults the Heart and Stomach Yang sinks, the tongue often suddenly becomes devoid of coating; if prolonged, it turns dark or purple.) In cases of insufficient fluids in the Stomach and Kidney, the tongue is often red without coating, or has a red line in the center, or many red spots on the tip and edges. This describes the general appearance of a normal tongue's coating. (I have seen healthy individuals with a coin-sized, smooth, pale purple area in the center of the tongue who only suffered from nocturnal emissions, with no other illnesses.)
If illness is present, the tongue will certainly show coating. Pathogens hide inside, while the coating manifests outside; this is reliable and accurate, leaving no room for error. Physicians rely primarily on this to grasp the condition, so it must not be neglected.
Fenghan [Wind-Cold] belongs to cold-dry pathogens, while Fengwen [Wind-Warmth] belongs to warm-dry pathogens. Fenghan initially affects the exterior, whereas Fengwen first injures the Qi level of the Lung Meridian. Thus, the tongue often lacks coating; even if there is a thin white or yellow coating, it is slippery. As the pathogen gradually transmits inward, it binds with fecal matter in the Stomach and Intestines, causing the coating to thicken, turn from white to yellow, then to black and dry. Its appearance is rigid and stagnant. Only after purgation does the coating begin to decompose ("rot"). "Rot" refers to a loose, non-rigid state. As the rot recedes, a new layer of thin, floating coating grows, indicating the complete resolution of the pathogen.
Some cases present with white coating from the onset that is dry like white sand, named "Sha Tai" [Sand Coating]. This indicates excessive warm-dry pathogen, requiring rapid purgation assisted by sweet-cool fluids-nourishing herbs. There are also cases where the coating turns black but remains moist, or where one or two white strips appear within yellow-black coating, or where the front of the tongue is dry but the root has thick white coating; these are due to concurrent dampness or phlegm-fluid retention. Conversely, if the coating is yellow or black but washes off thinly without a base ("ge di"), it indicates Yin deficiency of the Stomach. The presence or absence of a base in the coating is a major distinction between deficiency and excess patterns. (I once observed a patient with a thick, rigid white coating at the tongue root resembling water-soaked material, with two red flesh spots appearing on both sides, indicating accumulation of cold-water in the Lower Jiao and failure of True Yang to circulate.)
Dampness is a turbid pathogen with numerous complicated presentations. Wind-damp attacking the exterior typically presents with slippery, white, non-thick coating; cold-damp attacking the interior typically presents with greasy, white, thick coating.
Shuwen [Summerheat-Warmth], Shiwenn [Damp-Warmth], Wenyi [Plague-Warmth], and Wenre [Warm-Thermal] diseases all stem from the stagnation and steaming of damp-earth Qi. Dongwen [Winter-Warmth] arises because Yang fails to store itself properly, representing residual damp-earth steaming Qi. These pathogens enter through the mouth and nose into the Membrane Source (Lung/Stomach), manifesting from the interior outward. Chunwen [Spring-Warmth] results from winter cold injury, where cold stagnates and transforms into heat over time. Cold-dry Qi can bind fluids and water-retention, hiding in the Membrane Source, mixing with heat, and manifesting from the interior. Shushi wanfa [Late-onset Summerheat-Dampness], known as Fushu [Hidden Summerheat], occurs when summer heat-damp hides in the Membrane Source, and autumn cool-dry Qi from the exterior suppresses the internal summerheat-damp, triggering an outbreak via exterior pathogens moving interior pathogens. Shushi maji [Summerheat-Damp Malaria] also often arises this way. Since hidden pathogens and seasonal pathogens emerge from the interior, they often involve dampness. Thus, from the onset, the tongue shows white coating that is thick, not thin; greasy, not slippery; rough like accumulated powder; or mixed with pale yellow. When transmitting to the Stomach and transforming into fire, binding with fecal matter, it changes from white to yellow, black, and dry. However, Shuwen and Shiwenn pathogens often present as mixed yellow-white, appearing yellow or white, either yellow-greasy or gray-yellow, but never dry. Even if there are signs suitable for purgation, such as constipation or difficult defecation, one should use prepared Rhizoma Pinelliae (Xia Baihuang) gently to purge, because a non-dry coating suggests no dry feces in the intestines; stool resembles spoiled sauce, so aggressive purgation is contraindicated. This summarizes the tongue coatings of dry pathogen, damp pathogen, and mixed dry-damp pathogens. (From Shi Feinan's *Yi Yuan*.)
The tongue is the orifice of the Heart; all diseases manifest on the tongue. By distinguishing its color, the syndrome becomes clear. The tip governs the Heart, the center governs the Spleen and Stomach, the sides govern the Liver and Gallbladder, and the root governs the Kidney. If fluids are normal and there is no dry thirst, fever still indicates an exterior syndrome. If the coating is coarse and white, becoming thick and greasy, it indicates cold pathogen entering the Stomach, combining with turbid fluid retention and transforming into fire. At this stage, taste perception is lost; use Rhizoma Pinelliae (Banxia) and Herba Agastaches (Huoxiang). When the thick greasy coating turns yellow, the pathogen has transformed into fire; use Rhizoma Pinelliae (Banxia) and Radix Scutellariae (Huangqin). If severe heat is untreated, it turns black, indicating extreme Stomach fire; use Gypsum Fibrosum (Shigao) and Rhizoma Pinelliae (Banxia). If black and dry/cracked, remove Rhizoma Pinelliae (Banxia) and use solely Gypsum Fibrosum (Shigao), Radix Anemarrhenae (Zhimu), Ophiopogonis Radix (Maidong), and Radix Trichosanthis (Huafen) to moisten. As thick coating recedes and the tongue body turns red, it indicates fire burning and water deficiency; use Rehmanniae Radix (Shengdi), Adenophorae Radix (Shashen), Ophiopogonis Radix (Maidong), and Dendrobii Caulis (Shihu) to nourish. This represents exterior pathogen transmitting inward. In cases of Spleen-Stomach deficiency-cold, the tongue is white, devoid of coating, and moist; severely, lips, mouth, and complexion appear sallow and pale, possibly due to diarrhea or dampness, lacking Spleen fire. Quickly use Codonopsis Radix (Dangshen), Fried Atractylodis Macrocephalae Rhizoma (Jiaozhuzhu), Aucklandiae Radix (Muxiang), Poria (Fuling), Glycyrrhizae Radix et Rhizoma Praeparata (Zhigancao), Zingiberis Rhizoma (Ganjiang), and Jujubae Fructus (Dazao) to boost Yang. For severe deficiency threatening collapse, add Aconiti Lateralis Radix Praeparata (Fuzi) and Cinnamomi Cortex (Rougui). For Spleen heat, the center coating is thin yellow; use Radix Scutellariae (Huangqin). For Heart heat, the tip is red, possibly with prickles; use Radix Et Rhizoma Rhei (Huanglian), Ophiopogonis Radix (Maidong), and Core Carapis (Zhujuanxin). For Liver heat, the sides are red or prickle; use Bupleuri Radix (Chaihu) and Gardeniae Fructus (Heishanzhi). Thick yellow coating in the center indicates mild Stomach heat; use Dendrobii Caulis (Shihu), Radix Anemarrhenae (Zhimu), Radix Trichosanthis (Huafen), and Ophiopogonis Radix (Maidong). Thick black-dry coating in the center indicates severe Stomach heat; Gypsum Fibrosum (Shigao) and Radix Anemarrhenae (Zhimu) are essential. If gums, lips, and mouth turn black, the Stomach is about to rot; rescue requires large doses of Gypsum Fibrosum (3-4 liang), Raw Radix Et Rhizoma Rhei (1 liang), plus Fen Jin Zhi (Faecal Golden Juice), Ren Zhong Huang (Human Middle Yellow), fresh Rehmanniae Radix juice, Asparagus Cochinchinensis Radix juice, Ophiopogonis Radix juice, and Lonicerae Flos Dew. This is common in epidemic macules and Shanghan syndromes. I once treated an only son, using over 14 jin of Gypsum Fibrosum before macules erupted and disease subsided; this relied entirely on diagnostic insight. Black coating that is moist indicates Kidney deficiency; use Liuwei Dihuang Wan (Six-Ingredient Pill with Rehmannia). Full-tongue red-purple without coating is called Jiang She [Crimson Tongue], also indicating Kidney deficiency; use Shengdi, Shudi, Tiandong, Maidong. After illness, a crimson tongue shiny like a mirror, or dry throat without desire for cold drinks, indicates extreme Kidney Water deficiency; use large doses of Liuwei Dihuang Wan to save fluids, otherwise desiccation ensues. (From Jiang Bihua's *Yi Jing*.)
Tongue coating arises from internal heat causing Spleen Qi stagnation, leading to accumulation of food fluids internally, thus manifesting externally. If Spleen Qi is not stagnant, digestion proceeds, fluids circulate, and even with high heat, coating may not form. (In my practice, patients with internal cold-damp often lack coating until warming-dispersing formulas are administered, after which white coating appears, turns yellow, and the disease resolves.) Cyan tongue, or cyan-purple and cold/slippy, indicates cold syndrome. Cyan-purple, dry/scorched, swollen, or contracted tongue indicates heat syndrome. Extreme cold also causes contraction due to cold contracting sinews, but it will not be dry/scorched. Tongue stiffness, shortening, coma, and confused speech indicate untreatable conditions. Phlegm disorders can cause tongue hardness/contraction and coma/speechlessness; differentiate by physical signs, color, and pulse. In heat diseases, tongue ulceration with unrelenting heat is fatal. In Shanghan, Yin-Yang Yi disease with tongue protruding several inches is fatal. (Note: This is actually relapse due to sexual exhaustion, not Yin-Yang Yi. From Guo Yuanfeng's *Mai Ru*.)