凡察色辨苔。但有白、黄、黑三种。此为结苔之现色。察色辨舌。亦有绛、紫、青
三种。此为舌本之变色。苔色白而薄者。寒邪在表。宜发表。或气郁不舒。宜宣气。白
而浓者。中脘素寒。宜温中。或湿痰不化。宜化痰。兼发纹满布者多寒湿。宜温化。如碱而腻
者多浊热。宜清化。若苔白而浓。其上如刺。起焦裂纹。扪之或糙或涩者。多为热极之
下证。急宜寒泻。惟淡白如无。为虚寒。宜温补。亦有属热者。宜参脉症以治之。白如煮
熟者。为 白苔。俗称呆白苔。症多不治。若苔色黄。虽邪热渐深。但有带白不带白之
分。有质地无质地之别。黄苔带白。薄而无质地者。表邪未罢。热未伤津。尚宜宣气达
表。黄苔而浊。不带白而有质地者。邪已结里。黄浊愈甚。则入里愈深。热邪愈结。由
于湿热多痰者。宜辛淡清化。由于湿热夹食者。宜苦辛通降。惟黄而糙。黄而燥。剧则
黄而带灰带黑。黄而干砂刺点。黄而中心瓣
裂者。皆为里热结实。均当速下以存津液。至苔黑色。有带青、带紫、焦燥、津润之不
同。苔色青黑而舌本滑润者。为水来克火。多脾肾阴寒证。急宜破阴回阳。苔色紫黑而
舌本焦燥者。为火极似水。多胃肾阴涸证。急宜泻火救阴。他如灰色（即淡黑。）灰带
白色而滑者。为寒湿伤脾阳。宜温脾化湿。灰带黑色而燥者。为湿火伤脾阴。宜润脾救
阴。霉酱色（即黄兼黑。）多由夹食伤寒。浊腐上泛。急宜清下。色淡者生。色浓者死
。下之得通者生。不得通者死。此辨苔色之要诀也。余已详六经舌苔中。兹不赘述。若
夫舌色由红转绛转紫者。皆有色而无苔。一由心经热炽。劫伤经血。宜滋血清营。虚甚
者滋阴复脉。一由肝经火旺。劫伤络血。宜凉血通络。邪盛者。泻火熄风。惟舌青为
肝脏本色发现。胃中生气已极。虽有青黑寒化。青紫热化之殊。然竭力挽救。终多不治
。余亦载六经舌苔中。学人参看可也。此为察色辨舌。当分苔色舌色之要诀。
【秀按】张诞先。本于申斗垣舌辨。稍加修饰。纂《舌鉴》一卷。共舌图一百二十
。每借一色。即化为数十图。语多穿凿。未免眩人心目。俞氏了了数言。已括其要。
【廉勘】东江刘吉人。着察舌辨症新法。其看舌八法。一看舌色。二看舌质。（
质亦有色、又有大小温热之症、舌质胀大满口、迹有齿印血热之症、质底色紫色红之别
。）三看舌尖。（白苔满舌、尖有红刺、勿用温燥之药、）四看舌心。（四边有苔、中
无、或中有直裂、或有直槽、或横裂。）五看舌根。（根后有无苔色接续、有无大肉
瘤。）六看舌边。（苔色与边齐否。）七看燥润。（燥润为辨舌两大纲、有以手扪之、
或滑润、或燥刺棘手、有看似润而摸之燥者、有看似燥而摸之滑者。）八看老嫩。（苍
老者多实症、胖嫩者多虚症。）其第一章。论舌苔原理曰。舌为胃之外候。以输送食物
入食管胃脘之用。其舌体之组织。系由第五对脑筋达
舌。其功用全赖此筋运动。舌下紫青筋二条。乃少阴肾脉上达。名曰金津玉液二穴。所
以生津液以濡润舌质拌化食物者也。中医以舌苔辨症者。以其苔堆于表面。易于辨认。
而未知苔因何而生。其辨症之识。必有毫厘千里之误。此原理之不可不讲也。夫舌之表
面。乃多数极小乳头铺合而成。此乳头极小微点。其不易见时。非显微镜不能窥见。易
见时。形如芒刺。摸之棘手。或隐或现。或大或小。或平滑。或高起。随时随症。变易
不定。苔即胃中食物腐化之浊气。堆于乳头之上。此舌苔所由生也。（廉勘苔虽由胃浊
上升、但其所生者、多由于胃肠内膜、层递而上。盖因舌膜直接胃肠故也。）常人一日
三餐。故舌苔亦有三变。谓之活苔。无病之象也。其所以能变者。因饮食入胃时。将腐
浊遏郁下降。故苔色一退。至饮食腐化。浊气上蒸。苔色又生。胃无腐浊。则苔薄而少
。有腐浊。则苔多而浓。此其常理也。故苔色以微黄为正。若白为肺色。胃阳被饮食抑
遏。或有积湿。或因粘涎。正色反不能直达而上。故有暂白之时。惟青为绝色。青蓝之
色。现于舌上。其人命必危。此外尚有似黄非黄。似白非白。各类间色。皆条分于后。
以备后学细心参考。其说可谓清切矣。足为观察苔色之目标。
凡察苔色。与虚实最多关系。如苔色黄浊者为实。可用苦辛通降。若黄白相兼。间
有淡灰者为虚。但宜轻清化气。（如杏、蔻、橘、桔等品）黄浓而糙刺者为实。可攻泻
之。若黄薄而光滑者为虚。切忌攻泻。苔色黑而芒刺者为实。（肠有燥粪无疑）攻下刻
不容缓。若黑如烟煤隐隐而光滑者为虚。虚寒虚热。当旁参脉症以施治。白色如咸。白
如腻粉者皆为实。均宜苦辛开泄。粉苔干燥者实热尤盛。急宜苦寒直降。若白薄而淡。
及白而嫩滑者皆为虚。气虚阳虚。尤必细参脉症以治之。此为察色辨苔。当分虚实之要诀。
【秀按】张景岳曰。凡诊伤寒。以苔色辨表里寒热。确有可据。若以舌色辨虚实。
不能无误。例如黑苔。实
固能黑。以火盛而焦也。虚亦能黑。以水亏而枯也。竟有阴虚伤寒。其症似阳。舌黑如
炭。芒刺干裂者。用甘温壮水药。诸症渐退。但舌黑不减。后数日。忽舌上脱一黑壳。
内则新肉灿然。始知其肤腠焦枯。死而复活云云。观此。则舌黑起芒刺。未必皆实。尤
必于其舌本之老嫩。脉症之虚实。详辨以参定之。
【廉勘】杨潜村观舌心法云。凡舌苔由白而黄。由黄而焦。或枯黑燥裂。若察其舌
边胖大。舌底滑润者。甚有舌底燥嫩。绝无津液。或糙刺如砂皮。或敛束如荔枝壳者。
多因劳伤脾肺。气虚发热。医者但知为伤寒。误用发散。益虚益热。又误认为实热。复
用寒凉。重阴内逼。以致虚火上炎。所以白上加黄。黄上加焦。而枯黑燥裂也。不论其
脉。不论其症。大剂参附养荣汤。不时灌服。多有得生者。然其舌质。未有不胖且嫩者
。苔色干燥滑润。又在所不拘也。若苔色因实火焦黑。则其形必坚敛。色必苍老。其舌
质万无胖嫩者。此皆察色者所不可不知也。观此。则病之虚实。验之于苔。但能据以定
症之虚实。不能据以定体质之虚实。
凡舌有质地。而坚敛苍老。不拘苔色白黄灰黑。由舌中延及舌边。揩之不去。刮之
不净。底仍粗涩粘腻。不见鲜红者。是为有根之真苔。中必多滞。舌无质地。而浮胖娇
嫩。不拘苔色白黄灰黑。满布舌中。不及舌边。揩之即去。刮之即净。底亦淡红润泽。
不见垢腻者。是为无根之假苔。里必大虚。即看似苔色满布。饮食后苔即脱去。舌质圆
浮胖嫩者。亦属假苔。一名活苔。他如食枇杷则苔色黄。食橄榄则苔色青黑。是为假色
之染苔。故苔有质地与无质地。延及舌边与但布舌中。过辨虚实之大纲。此为察色辨
苔。当分真假之要诀。
【廉勘】陆氏冷庐医话曰。临症视舌。最为可凭。然亦未可执一。正义云。凡见黑
舌。问其曾食酸咸等物。则能染成黑色。非因病而生也。然染成之黑。必润而不燥。刮
之即退为异。又惟虚寒舌润能染。若实热舌苔干燥 何能染及耶。凡临证欲视病患舌苔
燥润。禁饮汤水。饮后则难辨矣。重庆堂随笔云。淡舌白苔。亦有热
症。黄浓满苔。亦有寒症。舌绛无津。亦有痰症。当以脉症便溺参勘。又如灯下看黄苔
。每成白色。然则舌虽可凭。而亦未尽可凭。非细心审察。亦难免于误治。故俞氏谓临
症辨舌。亦须活法推求。真阅历精深之语也。
凡苔薄者表邪初见。苔浓者里滞已深。固已。但要辨其薄而松者无质。揩之即去。
为正足化邪。即薄而腻者。邪入尚浅。亦宜宣气达邪。惟浓而腻者有地。揩之不去。多
秽浊盘踞。若浓而松者。里滞已化。但须轻清和解。此为察色辨苔。当分浓薄松腻之要
诀。
凡舌苔始终一色。不拘白黄灰黑。即有浓薄滑涩干润浓淡之不同。总属常苔。当参
脉症以施治。如舌一日数变。或由白而黄。由黄而黑。或乍有乍无。乍赤乍黑者。皆为变
苔。其症多凶而少吉。此为察色辨苔。当分常变之要诀。
凡舌苔由腻化松。由浓退薄。乃里滞逐渐减少之象。是为真退。即有续生薄白新苔
者。尤为苔真退后。胃气渐复。谷气渐进之吉兆。若满舌浓苔。忽然退去。舌底仍留污
质腻涩。或见朱点。或有发纹者。是为假退。一二日间。即续生浓苔。又有满舌浓苔。
中间驳落一瓣。或有罅纹。或有凹点。底见红燥者。须防液脱中竭。用药切宜审慎。若
浓苔忽然退去。舌光而燥者。此胃气将绝也。多凶少吉。此为察色辨苔。当分真退假退
驳去脱竭之要诀。
凡舌苔糙者多秽浊。粘者多痰涎。固已。惟浓腻与浓腐。尤宜明辨。浓腻者固多食
积。亦有湿滞。刮之有净有不净。或微浓而刮不脱。虽有邪从火化。渐积而干。而舌本尚
罩一层粘涎。是为浓腻之常苔。若浓腐虽多由胃液腐败。然有脓腐霉腐之别。如舌上生
脓腐。苔白带淡红。粘浓如疮中之脓。凡内痈最多此症。肺痈肠痈多白腐苔。胃痈多黄
腐苔。肝痈腰痈多紫黑腐苔。下疳结毒仍多白腐苔。若霉腐苔。满舌生白衣如霉苔。或
生糜点如饭子样。皆由食道延上。先因咽喉而起。继则延累满舌。直至满口唇齿皆有糜
点。多见于湿温、温毒、伏暑、赤痢、梅毒、疳积等
症。此由胃体腐败。津液悉化为浊热。中无砥柱。蒸腾而上。无论白腐黄腐。其病总多
不治。是为浓腐之霉苔。此为察色辨苔。当分糙粘及浓腻与浓腐之要诀。
若夫察看舌色。则舌色本红。淡于红者血虚也。淡红无苔。反微似黄白苔者。气不化液也。甚则淡红
带青者。血分虚寒也。妇人子宫冷者有之。苔死腹中者亦有之。久痢虚极者亦恒见之。
浓于红者为绛。血热也。尖绛者、心火上炎也。根绛者、血热内燥也。通绛无苔。及似
有苔粘腻者。血热又挟秽浊也。绛而深紫。紫而润黯者。中脘多瘀。紫而干晦者。肝肾
气绝。由绛而紫。紫而转黑者。络瘀化毒。血液已枯。不治。若舌本无苔。隐隐若罩黑
光者。平素胃燥舌也。烟家多有此舌。此为察色辨舌。当分舌色淡浓之要诀。
【廉勘】舌之有苔。犹地之有苔。地之苔。湿气上泛而生。舌之苔。胃蒸脾湿上潮
而生。故胎或作苔。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。但不满不板滞。其脾胃湿热素重者。往往终年有浓白苔。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。其胃肾
津液不足者。舌多赤而无苔。或舌尖舌边多红点。若舌中有红路一条。俗称鸡心苔。血
液尤虚。此平人舌苔之大较也。凡临症察看苔色舌色。必先问其平素舌苔何如。始有准
的。
【荣斋按】舌苔无论何色，皆有治法，惟舌质变，则为难治。然舌质既变，亦要察
其色之死活；活者、细察底里，隐隐犹见红活，此不过气血之有阻滞，非脏气之败坏也
；死者、底里全变干晦枯萎，毫无生气，是脏气不至矣！所谓真脏之色也。辨舌色当中
，以辨舌之黑色最难，然亦有“难里找易”的方法；如黑而干焦、肿硬、卷缩、芒刺者
，属实热证；其脉必洪数沉实，证必大热狂躁，宜白虎、承气等方。黑而白、黑而灰、
黑而紫、湿润软滑者，属虚寒证；脉必微弱，证必恶寒，宜四逆辈。此辨黑舌之方法，
古今医学文献中都有这样的
记载，特把它举出一个例子如上。
凡观察舌色和辨别舌苔，主要只有白、黄、黑三种颜色。这是舌苔呈现的颜色。观察舌质颜色和辨别舌体，也有绛、紫、青三种颜色。这是舌体本质的变色。
舌苔白色而薄的，是寒邪在表，宜用发表法；或者是气机郁滞不舒，宜用宣通气机法。舌苔白色而厚的，是中脘（胃脘部）素来虚寒，宜用温中法；或者是湿痰不能化解，宜用化痰法。如果兼有裂纹满布舌面，多属寒湿证，宜用温化法。如果舌苔像碱一样腻浊，多属浊热证，宜用清化法。如果舌苔白而厚，上面像刺一样起焦裂纹，摸上去或粗糙或涩手，多为热极导致的下焦实证，急宜用寒凉泻下法。只有舌苔淡白若无，属于虚寒证，宜用温补法。也有属于热证的，应参考脉象和症状来治疗。舌苔白得像煮熟的样子，称为“白苔”，俗称呆白苔，这种病症大多难治。
如果舌苔色黄，虽然邪热逐渐深入，但有带白和不带白之分，有质地和无质地之别。黄苔带白，薄而无实质感的，说明表邪未解，热邪尚未伤及津液，仍宜用宣通气机、透达表邪的方法。黄苔而浊腻，不带白而有实质感的，说明邪气已结于里，黄浊越严重，则入里越深，热邪越结聚。由于湿热夹痰引起的，宜用辛味淡味药清化湿热；由于湿热夹食积引起的，宜用苦味辛味药通降泄热。只有黄而粗糙、黄而干燥的，严重时黄中带灰带黑，黄而干如砂刺点状，黄而中心瓣裂的，都属于里热结实证，都应当迅速使用攻下法以保存津液。
至于舌苔黑色，有带青、带紫、焦燥、津润的不同。舌苔色青黑而舌体滑润的，是水来克火，多属脾肾阴寒证，急宜用破阴回阳法。舌苔色紫黑而舌体焦燥的，是火极似水，多属胃肾阴液枯竭证，急宜用泻火救阴法。其他的如灰色（即淡黑色），灰白带滑的，是寒湿损伤脾阳，宜用温脾化湿法；灰黑而燥的，是湿火损伤脾阴，宜用润脾救阴法。霉酱色（即黄兼黑），多由夹食伤寒引起，浊腐之气上泛，急宜用清下法。色淡者生，色浓者死。攻下后大便得通的生，不得通的死。这是辨别苔色的关键要点。其余已在六经舌苔中详细论述，这里不再赘述。
至于舌色由红转绛转紫的，都是有颜色而无舌苔。一种是由心经热炽盛，劫伤经络之血，宜用滋血清营法，虚甚的用滋阴复脉法；一种是由肝经火旺，劫伤络脉之血，宜用凉血通络法，邪盛的用泻火熄风法。只有舌青是肝脏本色显露，说明胃中生气已极度衰竭，虽然有青黑寒化、青紫热化的不同，但竭力挽救，大多难治。我也记载在六经舌苔中，学者可以参考观看。这是观察舌色和辨别舌体，应当区分苔色和舌色的关键要点。
【秀按】张诞先，依据申斗垣的舌诊方法，稍加修饰，编纂《舌鉴》一卷，共有舌图一百二十幅。每种借一种颜色，就化为数十幅图，言语多有穿凿附会，未免眩惑人心。俞氏寥寥数语，已概括其要领。
【廉勘】东江刘吉人，著有《察舌辨症新法》。他看舌头的八种方法：一看舌色，二看舌质。（舌质也有颜色，又有大小温热之症的区别，舌质胀大满口，边缘有齿印的是血热之症，舌质底色有紫色和红色的区别。）三看舌尖。（白苔满舌，尖上有红刺，不要用温燥的药。）四看舌心。（四边有苔，中间无，或者中间有直裂，或者有直槽，或者横裂。）五看舌根。（根后有无苔色接续，有无大肉瘤。）六看舌边。（苔色是否与舌边齐平。）七看燥润。（燥润是辨舌的两大纲领，用手摸上去，有的滑润，有的燥刺棘手，有的看似润而摸起来燥，有的看似燥而摸起来滑。）八看老嫩。（苍老的多数是实证，胖嫩的多数是虚证。）他的第一章，论舌苔原理说：舌是胃的外候，用来输送食物进入食管胃脘。舌体的组织，是由第五对脑神经到达舌头，其功能全靠这条神经运动。舌下紫青色筋两条，是少阴肾脉上达，名叫金津玉液二穴，所以生津液来濡润舌质并拌化食物。中医用舌苔辨证，是因为苔堆积在表面，易于辨认，却不知道苔因何而生，其辨证的识见，必有毫厘千里的错误。这是原理不可不讲的原因。舌的表面，是由多数极小的乳头铺合而成，这些乳头极小微点，不易看见时，非显微镜不能窥见，容易看见时，形状如芒刺，摸之棘手，或隐或现，或大或小，或平滑，或高起，随时随症，变易不定。苔就是胃中食物腐化的浊气，堆积在乳头上，这就是舌苔产生的原因。（廉勘认为苔虽由胃浊上升，但其所生的地方，多由于胃肠内膜，层递而上。因为舌膜直接连接胃肠的缘故。）常人一日三餐，所以舌苔也有三次变化，称为活苔，是无病的征象。之所以能变化，是因为饮食入胃时，将腐浊遏郁下降，所以苔色一退，到饮食腐化，浊气上蒸，苔色又生。胃中没有腐浊，则苔薄而少，有腐浊，则苔多而厚。这是常理。所以苔色以微黄为正色，若白为肺色，胃阳被饮食抑制遏郁，或有积湿，或因粘涎，正色反而不能直达而上，所以有暂白的时刻。只有青色是绝症之色，青蓝之色现于舌上，其人命必危。此外尚有似黄非黄，似白非白，各类间色，都条分缕析在后面，以备后学细心参考。他的说法可谓清晰确切，足为观察苔色的目标。
凡观察苔色，与虚实最多关系。如苔色黄浊者为实证，可用苦辛通降法。若黄白相兼，间有淡灰色的为虚证，只宜轻清化气。（如杏仁、豆蔻、橘皮、桔梗等品）。黄浓而糙刺者为实证，可攻泻之。若黄薄而光滑者为虚证，切忌攻泻。苔色黑而芒刺者为实证。（肠中有燥粪无疑），攻下刻不容缓。若黑如烟煤隐隐而光滑者为虚证，虚寒虚热，当旁参脉症来施治。白色如盐，白如腻粉的都是实证，均宜苦辛开泄。粉苔干燥者实热尤盛，急宜苦寒直降。若白薄而淡，及白而嫩滑的都是虚证，气虚阳虚，尤其必须细参脉症来治疗。这是观察舌色辨别苔色，应当区分虚实的要点。
【秀按】张景岳说：凡诊治伤寒，以苔色辨别表里寒热，确有依据。若以舌色辨别虚实，不能无误。例如黑苔，实证固能黑，是因为火盛而焦枯；虚证也能黑，是因为水亏而枯槁。竟有阴虚伤寒，其症似阳，舌黑如炭，芒刺干裂的，用甘温壮水药，诸症渐退，但舌黑不减，后数日，忽舌上脱下一黑壳，内则新肉灿烂，才知道是肤腠焦枯，死而复活之类的话。观此，则舌黑起芒刺，未必都是实证，尤其必须在舌本的老嫩，脉症的虚实，详细辨别来参定。
【廉勘】杨潜村观舌心法说：凡舌苔由白而黄，由黄而焦，或枯黑燥裂，若察看其舌边胖大，舌底滑润的，甚至有舌底燥嫩，绝无津液，或糙刺如砂皮，或敛束如荔枝壳的，多因劳伤脾肺，气虚发热，医者只知道是伤寒，误用发散药，益虚益热，又误认为是实热，再用寒凉药，重阴内逼，以致虚火上炎，所以白上加黄，黄上加焦，而枯黑燥裂。不论其脉，不论其症，大剂参附养荣汤，不时灌服，多有得生的。然而其舌质，没有不胖且嫩的。苔色干燥滑润，又在所不拘了。若苔色因实火焦黑，则其形必坚敛，色必苍老，其舌质万无胖嫩的。这都是观察舌色的人不可不知道的。观此，则病的虚实，验之于苔，只能据以定症之虚实，不能据以定体质之虚实。
凡舌有质地，而坚敛苍老，不拘苔色白黄灰黑，由舌中延及舌边，揩之不去，刮之不净，底仍粗涩粘腻，不见鲜红的，是为有根的真苔，中必多滞。舌无质地，而浮胖娇嫩，不拘苔色白黄灰黑，满布舌中，不及舌边，揩之即去，刮之即净，底亦淡红润泽，不见垢腻的，是为无根的假苔，里必大虚。即看似苔色满布，饮食后苔即脱去，舌质圆浮胖嫩的，也属假苔，一名活苔。其他如吃枇杷则苔色黄，吃橄榄则苔色青黑，是为假色的染苔。所以苔有质地与无质地，延及舌边与但布舌中，是辨别虚实的大纲。这是观察舌色辨别苔色，应当区分真假的要点。
【廉勘】陆氏《冷庐医话》说：临症视舌，最为可凭，然而也不可执一。正义云：凡见黑舌，问其曾食酸咸等物，则能染成黑色，并非因病而生。然染成的黑，必润而不燥，刮之即退为异。又惟虚寒舌润能染，若实热舌苔干燥，何能染及耶？凡临证欲视病患舌苔燥润，禁饮汤水，饮后则难辨矣。《重庆堂随笔》说：淡舌白苔，亦有热症，黄浓满苔，亦有寒症，舌绛无津，亦有痰症，当以脉症便溺参勘。又如灯下看黄苔，每成白色。然则舌虽可凭，而亦未尽可凭，非细心审察，亦难免于误治。所以俞氏谓临症辨舌，亦须活法推求，真是阅历精深的话。
凡苔薄者表邪初见，苔浓者里滞已深，固然如此。但要辨其薄而松的无质，揩之即去，为正足化邪，即薄而腻的，邪入尚浅，也宜宣气达邪。只有浓而腻的有地，揩之不去，多秽浊盘踞。若浓而松的，里滞已化，但须轻清和解。这是观察舌色辨别苔色，应当区分浓薄松腻的要点。
凡舌苔始终一色，不拘白黄灰黑，即有浓薄滑涩干润浓淡的不同，总属常苔，当参脉症来施治。如舌一日数变，或由白而黄，由黄而黑，或乍有乍无，乍赤乍黑的，皆为变苔，其症多凶而少吉。这是观察舌色辨别苔色，应当区分常变的要点。
凡舌苔由腻化松，由浓退薄，乃里滞逐渐减少之象，是为真退，即有续生薄白新苔者，尤为苔真退后，胃气渐复，谷气渐进的吉兆。若满舌浓苔，忽然退去，舌底仍留污质腻涩，或见朱点，或有发纹的，是为假退，一二日间，即续生浓苔。又有满舌浓苔，中间驳落一瓣，或有罅纹，或有凹点，底见红燥的，须防液脱中竭，用药切宜审慎。若浓苔忽然退去，舌光而燥的，此胃气将绝也，多凶少吉。这是观察舌色辨别苔色，应当区分真退假退驳去脱竭的要点。
凡舌苔糙者多秽浊，粘者多痰涎，固然如此。只有浓腻与浓腐，尤其宜明辨。浓腻者固多食积，也有湿滞，刮之有净有不净，或微浓而刮不脱，虽有邪从火化，渐积而干，而舌本尚罩一层粘涎，是为浓腻的常苔。若浓腐虽多由胃液腐败，然有脓腐霉腐之别。如舌上生脓腐，苔白带淡红，粘浓如疮中之脓，凡内痈最多此症，肺痈肠痈多白腐苔，胃痈多黄腐苔，肝痈腰痈多紫黑腐苔，下疳结毒仍多白腐苔。若霉腐苔，满舌生白衣如霉苔，或生糜点如饭子样，皆由食道延上，先因咽喉而起，继则延累满舌，直至满口唇齿皆有糜点，多见于湿温、温毒、伏暑、赤痢、梅毒、疳积等症。此由胃体腐败，津液悉化为浊热，中无砥柱，蒸腾而上，无论白腐黄腐，其病总多不治，是为浓腐的霉苔。这是观察舌色辨别苔色，应当区分糙粘及浓腻与浓腐的要点。
至于察看舌色，则舌色本红，淡于红的为血虚。淡红无苔，反微似黄白苔的，为气不化液。甚则淡红带青的，为血分虚寒，妇人子宫冷的有之，苔死腹中的也有之，久痢虚极的也恒常见。浓于红的为绛，为血热。尖绛的，为心火上炎。根绛的，为血热内燥。通绛无苔，及似有苔粘腻的，为血热又挟秽浊。绛而深紫，紫而润黯的，为中脘多瘀。紫而干晦的，为肝肾气绝。由绛而紫，紫而转黑的，为络瘀化毒，血液已枯，不治。若舌本无苔，隐隐若罩黑光的，为平素胃燥舌，烟家多有此舌。这是观察舌色辨别舌色，应当区分舌色淡浓的要点。
【廉勘】舌之有苔，犹地之有苔。地之苔，湿气上泛而生；舌之苔，胃蒸脾湿上潮而生，故胎或作苔。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，但不满不板滞。其脾胃湿热素重者，往往终年有浓白苔，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。其胃肾津液不足者，舌多赤而无苔，或舌尖舌边多红点。若舌中有红路一条，俗称鸡心苔，血液尤虚。此平人舌苔之大略也。凡临症察看苔色舌色，必先问其平素舌苔何如，始有准的。
【荣斋按】舌苔无论何色，皆有治法，惟舌质变，则为难治。然舌质既变，亦要察其色之死活；活者，细察底里，隐隐犹见红活，此不过气血之有阻滞，非脏气之败坏也；死者，底里全变干晦枯萎，毫无生气，是脏气不至矣！所谓真脏之色也。辨舌色当中，以辨舌之黑色最难，然亦有“难里找易”的方法；如黑而干焦、肿硬、卷缩、芒刺的，属实热证；其脉必洪数沉实，证必大热狂躁，宜白虎、承气等方。黑而白、黑而灰、黑而紫、湿润软滑的，属虚寒证；脉必微弱，证必恶寒，宜四逆辈。此辨黑舌之方法，古今医学文献中都有这样的记载，特把它举出一个例子如上。
Whenever observing the tongue color and distinguishing the coating, there are only three colors: white, yellow, and black. These are the presenting colors of the coated tongue. When observing the tongue body color and distinguishing the tongue substance, there are also three colors: crimson (Jiang), purple, and green/blue (Qing). These represent changes in the tongue substance itself.
A thin white coating indicates cold pathogen at the exterior; it is appropriate to use releasing-the-exterior methods. Alternatively, it may indicate stagnant Qi failing to flow smoothly; using methods to promote Qi circulation is appropriate. A thick white coating suggests inherent cold in the Zhongwan (epigastrium); warming the middle is appropriate. Alternatively, it may indicate unresolved damp-phlegm; resolving phlegm is appropriate. If accompanied by cracks covering the surface, it mostly indicates cold-dampness; warming and transforming is appropriate. If the coating appears greasy like alkali, it mostly indicates turbid heat; clearing and transforming is appropriate. If the white coating is thick with prickly, scorched cracks on top, feeling rough or coarse when touched, it mostly indicates extreme heat manifesting as a lower-jiao excess syndrome; urgent use of cold purgatives is required. Only if the coating is pale white and almost absent does it indicate deficiency-cold; warming and tonifying is appropriate. There are also cases belonging to heat; treatment should be guided by pulse and symptoms. A white coating resembling cooked rice is called "white coating," commonly known as "dull white coating"; such conditions are mostly incurable.
Regarding yellow coatings, although the pathogenic heat has gradually deepened, distinctions exist between those with residual white and those without, as well as between those with substance and those without. A yellow coating with white, thin and lacking substance, indicates that the exterior pathogen has not yet resolved and heat has not yet damaged body fluids; promoting Qi circulation and venting the exterior remains appropriate. A yellow coating that is turbid, lacks white, and has substance indicates that the pathogen has bound in the interior. The more severe the yellow turbidity, the deeper the pathogen has entered the interior, and the more intense the heat binding. If caused by damp-heat with much phlegm, pungent and bland herbs for clearing and transforming are appropriate. If caused by damp-heat combined with food stagnation, bitter and pungent herbs for unblocking and descending are appropriate. However, if the coating is yellow and rough, yellow and dry, or severely yellow with gray/black tints, yellow with dry sand-like points, or yellow with central fissures, all belong to interior heat-excess syndromes; rapid purgation is necessary to preserve body fluids.
As for black coatings, variations include those with green/blue or purple tints, scorched and dry, or moist. A green-black coating with a slippery tongue body indicates water overcoming fire, mostly representing spleen-kidney yin-cold syndromes; urgently breaking yin and restoring yang is required. A purple-black coating with a scorched and dry tongue body indicates extreme fire resembling water, mostly representing exhaustion of stomach-kidney yin fluids; urgently clearing fire and saving yin is required. Other types include gray color (i.e., light black): gray-white and slippery indicates cold-damp damaging spleen Yang; warming the spleen and transforming dampness is appropriate. Gray-black and dry indicates damp-fire damaging spleen Yin; moistening the spleen and saving yin is appropriate. Mustard-sauce color (i.e., yellow mixed with black) mostly results from cold damage complicated by food stagnation, with turbid rot rising upward; urgent clearing and purging is required. Light color indicates survival; dark color indicates death. Survival follows if purgation leads to bowel movement; death follows if it does not. This is the key to distinguishing coating colors. Details regarding the six meridians' tongue coatings have been discussed elsewhere and will not be repeated here.
Regarding tongue body colors changing from red to crimson to purple, these present color without coating. One type arises from blazing Heart channel heat robbing collateral blood; nourishing blood and clearing the nutritive level is appropriate, while nourishing yin and restoring the pulse is used for severe deficiency. Another type arises from flourishing Liver channel fire robbing collateral blood; cooling blood and unblocking collaterals is appropriate, while clearing fire and extinguishing wind is used for excess pathogens. Only a green/blue tongue reveals the true color of the Liver, indicating that the vital Qi of the stomach is extremely depleted. Despite differences between green-black cold transformation and green-purple heat transformation, efforts to save the patient often fail. This is also recorded in the section on six meridians' tongue coatings for scholars to reference. This constitutes the key distinction between coating color and tongue body color.
[Commentary by Xiu]: Zhang Danxian, basing his work on Shen Douyuan's tongue diagnosis, made slight modifications and compiled *She Jian* (Mirror of Tongues), containing one volume and 120 tongue diagrams. Borrowing each color, he generated dozens of diagrams per color; his language was often forced and obscure, potentially confusing readers. Yu's few words already captured the essence.
[Annotation by Lian]: Liu Jiren from Dongjiang authored *Cha She Bian Zheng Xin Fa* (New Methods for Observing Tongues and Distinguishing Syndromes). His eight methods for examining the tongue are: 1. Observe tongue color; 2. Observe tongue substance (substance also has color, size, and thermal characteristics; swelling filling the mouth with teeth marks indicates blood heat; base color differs between purple and red); 3. Observe the tip (white coating covering the tongue with red prickles at the tip contraindicates warm-drying herbs); 4. Observe the center (coating on sides but none in center, or vertical/horizontal fissures); 5. Observe the root (presence of continuous coating behind the root, presence of large fleshy tumors); 6. Observe the edges (whether coating aligns with edges); 7. Observe dryness/moisture (two major guidelines: touching reveals slipperiness or dry prickliness; some appear moist but feel dry, others appear dry but feel moist); 8. Observe old/tender (coarse/aged indicates excess; plump/tender indicates deficiency). In Chapter One, discussing the principle of tongue coating, he states: The tongue is the external manifestation of the Stomach, facilitating food transport into the esophagus and stomach. The tongue tissue is innervated by the fifth cranial nerve pair, its function relying entirely on this nerve's movement. Two purple-blue veins under the tongue are the Lesser Yin Kidney meridian ascending, named Jinjin and Yuye acupoints, generating saliva to moisten the tongue substance and mix with food. TCM uses coating for syndrome differentiation because it accumulates on the surface and is easy to identify, yet fails to understand why coating forms, leading to significant diagnostic errors. Thus, principles must be studied. The tongue surface consists of numerous tiny papillae. When invisible, microscopes are needed; when visible, they resemble thorns, feeling prickly, varying in visibility, size, smoothness, or elevation, changing constantly with symptoms. Coating is turbid qi from food putrefaction in the stomach accumulating on papillae. [Lian notes: Although coating rises from stomach turbidity, its origin lies in the gastrointestinal mucosa layer by layer, as the tongue membrane directly connects to the GI tract.] With three meals daily, the coating changes thrice, called "living coating," indicating no disease. Changes occur because food digestion causes turbidity to descend (coating recedes), then putrefaction causes turbidity to rise (coating reforms). Without turbidity, coating is thin/few; with turbidity, it is thick/abundant. This is normal. Slightly yellow is the correct color. White represents Lung color; if Stomach Yang is suppressed by diet, dampness accumulation, or sticky saliva, the correct color cannot reach the surface, causing temporary whiteness. Green/blue is an absolute sign of danger; its appearance portends critical condition. Other intermediate colors are detailed later for study. His views are clear and serve as a goal for observation.
Coating color relates most closely to excess and deficiency. Yellow-turbid coating indicates excess; bitter-pungent descending methods apply. Yellow-white mixed with faint gray indicates deficiency; light-clear Qi-transforming methods apply (e.g., Apricot Seed, Cardamom, Tangerine Peel, Kankudzu Root). Thick-yellow with rough prickles indicates excess; purgation applies. Thin-yellow and smooth indicates deficiency; purgation is strictly contraindicated. Black with prickles indicates excess (dry feces in intestines confirmed); purgation is urgent. Black like smoldering coal, hidden and smooth indicates deficiency; cold/heat deficiency requires referencing pulse/symptoms. White like salt or powder indicates excess; bitter-pungent opening/descending methods apply. Dry powdery coating indicates intense excess heat; bitter-cold direct descending is urgent. Thin-light white and tender-smooth white indicate deficiency; Qi/Yang deficiency requires careful pulse/symptom analysis. This is the key to distinguishing excess/deficiency in coating observation.
[Commentary by Xiu]: Zhang Jingyue stated that diagnosing Cold Damage via coating color to distinguish exterior/interior and cold/heat is reliable. However, using tongue color to distinguish excess/deficiency is error-prone. For example, black coating can be excess due to fire scorching, or deficiency due to water depletion. Yin-deficiency Cold Damage may mimic Yang patterns with charcoal-black, prickle-filled, cracked tongues; sweet-warm water-nourishing herbs reduce symptoms but leave the black tongue unchanged. Days later, a black crust peels off revealing fresh flesh, indicating skin/collateral scorching with revival. Thus, black prickles do not always mean excess; tongue substance age/tenderness and pulse/symptom excess/deficiency must be carefully analyzed.
[Annotation by Lian]: Yang Qiancun's method states: Coatings turning from white to yellow, yellow to scorched, or dry-black-cracked, especially with plump edges and slippery bases (or dry/tender bases without fluid, sandpaper-like texture, or lychee-shell contraction), often result from labor injuring Spleen/Lung, causing Qi-deficiency fever. Misdiagnosing as Cold Damage and using dispersants worsens deficiency/heat. Misdiagnosing as excess heat and using cold herbs traps Yin, causing deficient fire to flare. Hence white-to-yellow-to-scotched-to-black progression. Regardless of pulse/symptoms, large doses of Ginseng and Aconite Nourishing Harmony Decoction administered frequently often save lives. However, the tongue substance is invariably plump and tender. Coating dryness/moisture is secondary. If coating turns black due to excess fire, the shape is firm/constricted, color aged/coarse, and substance never plump/tender. Observers must know this. Disease excess/deficiency verified by coating determines syndrome nature, not constitutional nature.
Tongues with substance, firm/constricted/aged, regardless of coating color (white/yellow/gray/black), extending from center to edge, resistant to wiping/scraping, with rough/sticky/greasy base lacking fresh redness, are rooted true coatings, indicating internal stagnation. Tongues without substance, floating/plump/tender, regardless of coating color, covering center but not edges, easily removed by wiping/scraping, with pale-red/moist base lacking dirtiness, are unrooted false coatings, indicating severe interior deficiency. Even if coating covers fully, disappearing after eating with a round/plump/tender substance, it is also false/living coating. Eating loquat stains coating yellow; eating olive stains it green-black; these are dyed false colors. Thus, substance vs. no substance, extension to edges vs. center-only, distinguishes excess/deficiency. This is the key to distinguishing true/false coatings.
[Annotation by Lian]: Lu's *Lenglu Yihua* states: Tongue examination is reliable but not absolute. Justice says: If black tongue is found, ask about consuming sour/salty foods which dye it black, not disease-related. Dyed black is moist, not dry, and scrapes off. Only moist deficiency-cold tongues can be dyed; dry excess-heat tongues cannot. To observe coating dryness/moisture, forbid drinking water before examination. *Chongqing Tang Suibi* states: Pale tongue/white coating can indicate heat; thick-yellow-full coating can indicate cold; crimson tongue/no fluid can indicate phlegm; pulse/symptoms/urination/stool must be cross-referenced. Yellow coating looks white under lamplight. Thus, tongue signs are helpful but not infallible; careful scrutiny prevents misdiagnosis. Yu's statement that tongue diagnosis requires flexible application reflects profound experience.
Thin coating indicates initial exterior pathogen; thick coating indicates deep interior stagnation. However, thin/loose/non-substantial coatings that wipe off indicate sufficient Zheng Qi transforming pathogen. Even thin/greasy coatings indicate shallow pathogen entry; promoting Qi to vent pathogen is appropriate. Thick/greasy/substantial coatings that resist wiping indicate turbid stagnation. Thick/loose coatings indicate resolved interior stagnation; light-clear harmonizing is appropriate. This is the key to distinguishing thickness/looseness/greasiness.
Consistent coating color (white/yellow/gray/black) with variations in thickness/smoothness/dryness/moisture/lightness/darkness belongs to constant coatings; treat based on pulse/symptoms. Tongues changing multiple times daily (white-to-yellow, yellow-to-black, appearing/disappearing, red/black alternating) are variable coatings, indicating ominous prognosis. This is the key to distinguishing constant/variable coatings.
Coatings transforming from greasy to loose, thick to thin, indicate decreasing interior stagnation, termed true recession. Continued growth of thin-white new coating indicates recovering Stomach Qi and advancing grain Qi, a auspicious sign. Sudden disappearance of full-thick coating leaving dirty/greasy/rough base with red points or hair-like lines is false recession; thick coating returns within 1-2 days. Full-thick coating with central patch loss, fissures, or depressions showing red/dry base warns of fluid exhaustion/middle collapse; medication must be cautious. Sudden disappearance of thick coating leaving smooth/dry tongue indicates impending Stomach Qi extinction, mostly ominous. This is the key to distinguishing true/false recession and patch-loss/exhaustion.
Rough coatings indicate turbidity; sticky coatings indicate phlegm-saliva. Distinction between thick-greasy and thick-putrid is crucial. Thick-greasy usually indicates food stagnation or damp-stagnation; scraping yields mixed results. Slight thickness resisting scraping, even with fire-transformation drying, retains a layer of sticky saliva on the tongue body, constituting common thick-greasy coating. Thick-putrid usually results from Stomach fluid corruption, differing into pus-putrid and mold-putrid. Pus-putrid coating is white-with-faint-red, sticky/thick like wound pus, common in internal abscesses: Lung/Intestine abscesses show white-putrid coating; Stomach abscess shows yellow-putrid; Liver/Waist abscesses show purple-black-putrid; Chancre/toxic nodes show white-putrid. Mold-putrid coating features white film like mold or millet-grain-like erosions spreading from throat via esophagus to entire tongue/mouth/lips/teeth, seen in Damp-Warmth, Warm-Toxin, Hidden Summerheat, Dysentery, Syphilis, and Malnutrition syndromes. This results from Stomach body corruption, where fluids transform into turbid-heat, lacking a stabilizing force, steaming upward. Regardless of white/yellow putridity, prognosis is mostly poor, constituting thick-putrid mold coating. This is the key to distinguishing rough/sticky and thick-greasy/thick-putrid.
Regarding tongue body color: Red is normal. Paler than red indicates Blood deficiency. Pale-red without coating, slightly yellowish-white, indicates Qi failing to transform fluids. Very pale-red with green tint indicates Blood-level deficiency-cold, seen in uterine cold, dead-coating-in-abdomen, or chronic dysentery with extreme deficiency. Darker than red is crimson, indicating Blood heat. Crimson tip indicates Heart fire flaming upward. Crimson root indicates internal dryness from Blood heat. Uniform crimson without coating, or seemingly coated with stickiness, indicates Blood heat complicated by turbidity. Deep crimson turning purple, purple moist/dark indicates Stomach stagnation with blood stasis. Purple dry/dull indicates Liver-Kidney Qi exhaustion. Crimson-to-purple-to-black indicates collateral stasis transforming into toxin, blood exhaustion, incurable. Tongue body without coating, faintly covered with black sheen, indicates inherent Stomach dryness, common in smokers. This is the key to distinguishing pale/dark tongue colors.
[Annotation by Lian]: Tongue coating is like moss on ground; ground moss grows from rising damp; tongue coating grows from Stomach steaming Spleen damp rising. Normal people often have a layer of floating-white or floating-yellow coating. In summer, damp-earth dominance makes coating thicker and slightly yellow, but not full/stiff. Those with inherent Spleen-Stomach damp-heat often have thick-white coating year-round or gray-yellow center. During illness, Stomach-Spleen fluids oppressed by pathogen, or sinking Qi from diarrhea/dysentery, may result in no coating or thinner-than-normal coating. Kidney-Stomach fluid insufficiency leads to red tongue without coating, or red points on tip/edges. A red line in the center, called "chicken-heart coating," indicates severe Blood deficiency. This summarizes normal tongue coatings. Always ask patients about their habitual coating before clinical observation for accuracy.
[Commentary by Rongzhai]: All coating colors have treatments; only tongue substance changes are difficult to treat. However, even if substance changes, observe life/death of color: Living means underlying redness is still visible, indicating Qi/Blood stagnation, not organ failure. Dead means underlying area is completely dry/dull/withered, lacking vitality, indicating organ Qi cessation, i.e., True Organ Color. Among tongue colors, black is hardest to differentiate, but "finding ease within difficulty" exists: Black-dry-scrolled-hard/swollen/curled/prickly indicates excess-heat; pulse surging-rapid-deep-solid, symptoms high-fever/manic, treat with Baihu or Chengqi formulas. Black-white/gray/purple-moist-soft indicates deficiency-cold; pulse weak, symptoms aversion-to-cold, treat with Sini category. Such records exist in ancient/modern literature; this example illustrates the method.