诊面之法。有形焉。有容焉。分而言之。则理明。合而诊之。则病着。夫形也者。言乎其体也。容也者。言乎其态
也。以形为体。以态为用。而五脏之分。五志之辨。可由是而察焉。何者。怒则厉然而目张。喜则油然而颐解。
思则妪然而睑定。悲则瞿然而泣出。恐则薄然而气下。怒者肝之容。喜者心之容。思者脾之容。悲者肺之
容。恐者肾之容。此面容五脏之分也。怒则气逆。喜则气缓。思则气结。悲则气消。恐则气下。此五脏之分。五
志之病也。由是而观。有太过。有不及。太过者。病在外。不及者。病在内。太过则薄所胜。而乘所不胜。其不及
则所胜妄行。而所生受病。所不胜薄之也。然此就太过不及而言。又当随时以处中焉。中庸云。喜怒哀乐
之未发。谓之中。发而皆中节。谓之和。盖中者无所偏倚。和者无所乖戾。当喜怒而喜怒。当哀乐而哀乐。无
病之容也。其或发而不中。则有偏倚。发而失节。即有乖戾。故经曰。多阳者多喜。多阴者多怒。肝气虚则恐。
实则怒。心气虚则悲。实则笑不休。怒伤肝。悲胜怒。喜伤心。恐胜喜。思伤脾。怒胜思。忧伤肺。喜胜忧。恐伤肾。
思胜恐。盖以五志之变。合五行而推也。善诊者。观察病患之态。推而极之。补其偏。救其弊。则失中者中。而
违和者和矣。
诊察面部的方法，包括“形”和“容”两个方面。分开来说，道理就清晰了；综合起来诊察，病症就显露了。“形”，是指面部的形体结构；“容”，是指面部的神态表情。以形体为根本，以神态为表现，那么五脏的归属、五志（怒、喜、思、悲、恐）的区别，就可以由此观察出来了。为什么呢？发怒时，面容严厉且眼睛睁大；喜悦时，面容舒展且下巴放松；思虑时，面容郁结且眼睑静止；悲伤时，面容惊惧且流泪；恐惧时，面容怯弱且气机下沉。发怒是肝的神态，喜悦是心的神态，思虑是脾的神态，悲伤是肺的神态，恐惧是肾的神态。这就是面容与五脏的对应关系。发怒则气机上逆，喜悦则气机舒缓，思虑则气机郁结，悲伤则气机消耗，恐惧则气机下沉。这是五脏与五志病变的表现。由此看来，有太过，也有不及。太过者，病在体表（外）；不及者，病在体内（内）。太过则会克制其所胜（我克者），并乘袭其所不胜（克我者）；不及则其所胜者妄行，而其所生者受病，同时其所不胜者也会来欺凌它。然而这只是针对太过和不及而言，还应当根据具体情况把握中道。《中庸》说：“喜怒哀乐还没有发作的时候，叫做‘中’；发作出来都能符合节度，叫做‘和’。”所谓“中”，就是没有偏倚；所谓“和”，就是没有乖戾。该高兴时高兴，该悲哀时悲哀，这是无病的正常神态。如果情感发作不符合中道，就会有偏倚；发作失去节度，就会有乖戾。所以医经说：阳气多的人容易喜悦，阴气多的人容易发怒。肝气虚则易恐惧，肝气实则易发怒；心气虚则易悲伤，心气实则笑个不停。发怒伤肝，悲伤可以克制愤怒；喜悦伤心，恐惧可以克制喜悦；思虑伤脾，愤怒可以克制思虑；忧伤肺，喜悦可以克制忧愁；恐惧伤肾，思虑可以克制恐惧。这是根据五志的变化，结合五行相克的原理来推演的。善于诊察的医生，通过观察患者的神态，推究其极致的变化，补其偏颇，纠正其弊端，那么失中的人就能恢复中正，违背和谐的人就能恢复平和。
The method of examining the face involves two aspects: *xing* (form/structure) and *rong* (expression/demeanor). When analyzed separately, the principles become clear; when examined comprehensively, the diseases manifest. *Xing* refers to the physical structure of the face, while *rong* refers to its expressive demeanor. Taking form as the substance and demeanor as the function, one can observe the distinctions among the Five Zang Organs (Liver, Heart, Spleen, Lung, Kidney) and differentiate the Five Emotions (Anger, Joy, Pensiveness, Grief, Fear). Why is this so? Anger presents with a stern countenance and dilated eyes; joy presents with a relaxed countenance and unclenched jaw; pensiveness presents with a constrained countenance and still eyelids; grief presents with a startled countenance and flowing tears; fear presents with a timid countenance and sinking Qi (vital energy). Anger is the expression of the Liver; joy is the expression of the Heart; pensiveness is the expression of the Spleen; grief is the expression of the Lung; fear is the expression of the Kidney. This constitutes the correspondence between facial expressions and the Five Zang Organs. Anger causes Qi to rebel upward; joy causes Qi to relax; pensiveness causes Qi to knot; grief consumes Qi; fear causes Qi to sink. These are the pathological manifestations of the Five Zang Organs and the Five Emotions. From this perspective, there are conditions of excess and deficiency. Excess indicates disease in the exterior; deficiency indicates disease in the interior. In cases of excess, the organ overacts upon what it normally controls (Sheng cycle) and attacks what controls it (Ke cycle); in cases of deficiency, what it normally controls acts recklessly, what it generates suffers disease, and what controls it bullies it. However, this discussion pertains only to excess and deficiency; one must also apply the principle of the Mean according to circumstances. The *Zhongyong* (Doctrine of the Mean) states: "When the emotions of anger, joy, sorrow, and happiness have not yet arisen, it is called 'Zhong' (the Mean); when they arise and all accord with due measure, it is called 'He' (Harmony)." Zhong means having no bias; He means having no discord. Feeling anger or joy when appropriate, and sorrow or happiness when appropriate, represents the demeanor of health. If emotions arise without adhering to the Mean, there is bias; if they arise without proper measure, there is discord. Therefore, the classics state: Those with abundant Yang tend toward joy; those with abundant Yin tend toward anger. Liver Qi deficiency leads to fear; Liver Qi excess leads to anger. Heart Qi deficiency leads to grief; Heart Qi excess leads to incessant laughter. Anger injures the Liver; Grief overcomes Anger. Joy injures the Heart; Fear overcomes Joy. Pensiveness injures the Spleen; Anger overcomes Pensiveness. Sorrow injures the Lung; Joy overcomes Sorrow. Fear injures the Kidney; Pensiveness overcomes Fear. This deduction is based on the variations of the Five Emotions combined with the theory of the Five Elements (Wu Xing). A skilled examiner observes the patient's demeanor, deduces its extreme changes, supplements deficiencies, corrects abnormalities, thereby restoring balance to those who have lost the Mean and harmony to those who have deviated from it.