望色之法。部位既已参观。门户亦当合论。盖明堂察色。以入门户为凶。所谓门户者。阙庭肺门户。目肝门
户。耳肾门户。口心脾门户。若有气色入者皆死。白色见冲眉上。肺有病。入阙庭夏死。黄色见鼻上。脾有病。
入口者春死。青色见人中。肝有病。入目者秋死。黑色见颧上。肾有病。入耳者。六日死。赤色见颐上。心有病。
入口者冬死。盖五脏之色。各入本脏门户。至被克之时。为死期之日也。然必其色沉夭。则可谓云尔。脉经
曰。病患首部。耳目口鼻有黑气起。入于口者。为入门户。其病主死。是又以黑色为死气。以口为门户也。扁
鹊华佗察声色要诀云。肝病皮白。肺之日庚辛死。心病目黑。肾之日壬癸死。脾病唇青。肝之日甲乙死。肺
病颊赤目肿。心之日丙丁死。肾病面肿唇黄。脾之日戊己死。又凡病患及健人黑色。若白色起入目及鼻
口者。死在三日中。此二节。皆有门户吉凶之辨。部位生克之分。学人当参之十法。合之四时。庶可知其常变焉。
尝谓色分五行。则有生克。色分阴阳。则有宜忌。盖阳病而见阳色。阴病而见阴色者。宜也。阳病而见阴色。
阴病而见阳色者。忌也。是故邪盛于表。色宜浮清。反见沉浊者。忌也。气衰于里。色宜沉浊。反见浮清者。忌
也。身热烦躁。谵语妄言。其色宜赤。反见肢厥面青者。忌也。伤寒发汗。若吐若下。其色宜黄。反见热盛色赤
者。忌也。失血脱津液。色宜黄白。反见面色鲜赤者。忌也。下痢便脓血。色宜黄涩。反见身热面赤者。忌也。麻
痘斑疹。诸痛疮疡。色皆宜赤。反见青黑者。忌也。霍乱吐下。诸呕泄泻。色皆宜黄。反见青黯者。忌也。由是而
推。一病有一病之宜忌。一症有一症之宜忌。凡色病相应者。宜也。相反者。忌也。反之微者。难治。反之甚者。
即死。然犹有要焉。则在察其泽夭以知成败。察其浮沉。以知浅深。察其抟散。以知远近。视色上下。以知病
处。积神于心。以知往今。故经曰。相气不微。不知是非。属意弗去。乃知新故。此之谓也。若夫声音脉息之宜
忌。亦可以相应相反。比例而推焉。
望诊面色之法，在观察面部各部位气色之后，也应当结合“门户”理论进行综合论述。因为明堂（鼻部）察色时，若病色侵入门户则主凶兆。所谓“门户”，是指：阙庭（两眉之间）是肺的门户，眼睛是肝的门户，耳朵是肾的门户，口唇是心脾的门户。如果有气色侵入这些部位，都主死亡。
具体而言：白色出现在冲脉上行至眉毛上方的区域，表示肺有病；若病色侵入阙庭，则在夏季死亡。黄色出现在鼻部，表示脾有病；若病色侵入口唇，则在春季死亡。青色出现在人中沟，表示肝有病；若病色侵入眼睛，则在秋季死亡。黑色出现在颧骨上方，表示肾有病；若病色侵入耳朵，则在六日内死亡。赤色出现在下巴（颐部），表示心有病；若病色侵入口唇，则在冬季死亡。这是因为五脏的病色，各自侵入本脏对应的门户，遇到被克制的那个季节或日子，就是死亡的期限。但是，必须同时观察到颜色沉滞、枯夭无光泽，才能断言如此。
《脉经》说：病患头部，耳目口鼻出现黑气，并侵入口中，称为“入门户”，这种病症主死。这也是将黑色视为死气，将口视为门户。扁鹊和华佗关于察声色要诀中说：肝病而皮肤发白，在庚辛日（金克木之日）死亡；心病而眼睛发黑，在壬癸日（水克火之日）死亡；脾病而嘴唇发青，在甲乙日（木克土之日）死亡；肺病而脸颊发红、眼睛肿胀，在丙丁日（火克金之日）死亡；肾病而面部浮肿、嘴唇发黄，在戊己日（土克水之日）死亡。另外，凡是病患以及健康人，若有黑色或白色之气起于目、鼻、口等部位，多在三天内死亡。这两段内容，都包含了通过门户判断吉凶、通过部位分析生克的道理。学习者应当参考十种方法，结合四季变化，从而能够了解其常规与变通。
我曾说过：面色分为五行，就有相生相克的关系；面色分为阴阳，就有适宜与禁忌的区别。阳病见到阳色，阴病见到阴色，这是适宜的。阳病见到阴色，阴病见到阳色，这是禁忌的。因此，邪气盛于体表，面色宜浮浅清亮，反而见到沉滞浑浊的，是禁忌。正气衰于体内，面色宜沉滞浑浊，反而见到浮浅清亮的，是禁忌。身体发热烦躁，胡言乱语，面色宜红赤，反而见到四肢厥冷、面色发青的，是禁忌。伤寒经过发汗、催吐或泻下治疗后，面色宜黄，反而见到热盛色红的，是禁忌。失血或津液脱失，面色宜黄白，反而见到面色鲜红的，是禁忌。患痢疾便脓血，面色宜黄而晦涩，反而见到身热面红的，是禁忌。麻疹、痘疮、斑疹以及各种痛症疮疡，面色皆宜红赤，反而见到青黑色的，是禁忌。霍乱吐泻，各种呕吐泄泻，面色皆宜黄，反而见到青暗色的，是禁忌。由此类推，一种病有一种病的宜忌，一种症状有一种症状的宜忌。凡是面色与病症相应的，为适宜；相反的，为禁忌。相反轻微的，难治；相反严重的，立即死亡。然而还有关键之处，在于观察颜色的润泽与枯夭以知道预后的成败，观察颜色的浮沉以知道病位的深浅，观察颜色的聚散以知道病程的远近，观察颜色的上下分布以知道病变的部位，精神专注内心，以了解疾病的过去和现在。所以医经说：“观察气色若不细微，就不知道是非对错；意念专一不离去，才能知晓新旧病情。”说的就是这个道理。至于声音、脉象和呼吸的宜忌，也可以根据相应或相反的道理，类比推演出来。
The method of observing facial color, after examining the various regions of the face, should also be discussed in conjunction with the theory of "gateways" (Mén Hù). This is because when inspecting colors at the Ming Tang (nose), if pathological colors invade the gateways, it indicates an ominous sign. The so-called "gateways" refer to: Que Ting (the area between the eyebrows) is the gateway of the Lung; the eyes are the gateway of the Liver; the ears are the gateway of the Kidney; and the mouth/lips are the gateways of the Heart and Spleen. If any pathological color invades these areas, it signifies death.
Specifically: White appearing above the eyebrows along the Chong vessel indicates a disease of the Lung; if the color invades Que Ting, death occurs in Summer. Yellow appearing on the nose indicates a disease of the Spleen; if the color invades the mouth, death occurs in Spring. Cyan appearing in the philtrum indicates a disease of the Liver; if the color invades the eyes, death occurs in Autumn. Black appearing above the cheekbones indicates a disease of the Kidney; if the color invades the ears, death occurs within six days. Red appearing on the chin (Yi) indicates a disease of the Heart; if the color invades the mouth, death occurs in Winter. This is because the pathological colors of the Five Zang Organs each invade the gateway corresponding to their own organ, and the time of death corresponds to the season or day when they are overcome by the controlling element. However, this diagnosis holds only if the color is observed to be deep-set and dull/dry (Chen Yao).
The *Mai Jing* (Pulse Classic) states: If black qi arises in the head region of a patient—specifically around the eyes, ears, mouth, and nose—and enters the mouth, it is called "entering the gateway," and such a condition is fatal. This further identifies black as the color of death qi and the mouth as the gateway. The essential principles of observing voice and color by Bian Que and Hua Tuo state: In Liver disease, if the skin is white, death occurs on Geng-Xin days (Metal overcoming Wood); in Heart disease, if the eyes are black, death occurs on Ren-Gui days (Water overcoming Fire); in Spleen disease, if the lips are cyan, death occurs on Jia-Yi days (Wood overcoming Earth); in Lung disease, if the cheeks are red and eyes swollen, death occurs on Bing-Ding days (Fire overcoming Metal); in Kidney disease, if the face is swollen and lips yellow, death occurs on Wu-Ji days (Earth overcoming Water). Furthermore, whether in patients or healthy individuals, if black or white qi arises entering the eyes, nose, or mouth, death will occur within three days. These two sections both contain distinctions regarding auspiciousness and inauspiciousness via gateways, and divisions of generation and restriction via regions. Students should reference the ten methods and integrate them with the four seasons to understand both normal patterns and variations.
I have stated that when colors are divided into the Five Elements, there are relationships of generation and restriction; when colors are divided into Yin and Yang, there are appropriate (Yi) and inappropriate/contraindicated (Ji) manifestations. It is appropriate for Yang diseases to present with Yang colors, and for Yin diseases to present with Yin colors. It is contraindicated for Yang diseases to present with Yin colors, and for Yin diseases to present with Yang colors. Therefore, when pathogenic factors are abundant in the exterior, the complexion should be floating and clear; if instead it appears deep and turbid, it is contraindicated. When Qi is deficient in the interior, the complexion should be deep and turbid; if instead it appears floating and clear, it is contraindicated. In cases of fever, restlessness, delirium, and妄言 (wild speech), the complexion should be red; if instead there is cold extremities and a cyan face, it is contraindicated. After treating Cold Damage (Shang Han) with sweating, vomiting, or purging, the complexion should be yellow; if instead heat is excessive and the color is red, it is contraindicated. In cases of blood loss or depletion of body fluids, the complexion should be yellowish-white; if instead the face is bright red, it is contraindicated. In dysentery with pus and blood in the stool, the complexion should be yellow and dull; if instead there is fever and a red face, it is contraindicated. For measles, smallpox, macules/rashes, and various painful sores/ulcers, the complexion should generally be red; if instead it is cyan or black, it is contraindicated. In cholera with vomiting and diarrhea, or various other vomitings and diarrheas, the complexion should generally be yellow; if instead it is cyan and dark, it is contraindicated. By extending this reasoning, each disease has its specific appropriateness and contraindications, and each symptom has its own. Whenever the color corresponds to the disease, it is appropriate; when it contradicts, it is contraindicated. Mild contradictions are difficult to treat; severe contradictions lead immediately to death. However, there is a crucial aspect: one must observe the luster versus dullness to know success or failure; observe the floating versus sinking to know depth or superficiality; observe the clustering versus scattering to know proximity or remoteness of the pathology; view the upper and lower distribution of color to locate the disease site; and concentrate the spirit in the heart to understand the past and present of the illness. Thus, the Classics say: "If observation of Qi is not subtle, one cannot discern right from wrong; if attention is not maintained without departure, one cannot know the new from the old." This is what is meant. As for the appropriateness and contraindications of voice, pulse, and respiration, they can also be deduced by analogy based on correspondence or contradiction.