凡表邪之伤于外者，只以邪气所伤之部位论之，不必内动脏气也；即令病久，脏气亦为
扰累
，要总以邪气所伤之部为主，病在何部，即证见何部，无难察识也。惟脏气内伤，病隐于内
，证见于外，各有定象，察之不真，每易混淆。何者?五脏外应之候，每多相似，难于拘泥
，况又有兼脏之互相出入，故辨之不可不预也。兹撮其要，约有数端；一在经络所行之部，
如太阳、少阴行身之后，阳明、太阴行身之前，少阳、厥阴行身之侧是也；一在气化所充之
部，如脾主四肢与唇，肺主鼻与肩背，肝主宗筋、乳头与目，肾主二阴、腰脊与耳，心主面
与
舌是也；一见于脏气之功用，如肝主疏泄，心主神明，肺主出气，肾主纳气，脾主中焦，升
降诸气是也；一见于脏气所主之体，如肝主筋，心主脉，脾主肉，肺主皮毛，肾主骨是也
一见于色与色之部，色即肝青、心赤、脾黄、肺白、肾黑之五色；部即心额、肾颐、脾鼻准
、肺右颊，肝左颊，及《灵枢》所叙面之色部是也。以此数者，互合考之，病之所在，当无
遁矣。但其中尤以脏气之功用为主，经所谓省察病机，无失气宜也。察其前后数日证象之递
变者，其机属于何脏，即可了然病之所属矣。凡五脏真气自病，未有不相乘克者，如肝病克
脾，或脾虚为肝所乘，莫不先病之脏其证先见，后病之脏其证后见。《内经》曰∶肾乘心，
心先病，肾为应，色皆如是。此之谓也。故察外感者，必明五行之性情，与其功用之常变也
；察内伤者，必明五脏之性情，与其功用之常变也。
凡是外感表邪侵袭人体外部，只需根据邪气所侵犯的部位来讨论，不必牵涉到内部脏气的变动；即使病程迁延日久，脏气也会受到干扰和连累，但总体上仍以邪气所侵犯的部位为主，病在哪个部位，就会显现该部位的证候，不难辨识。只有当脏气受到内伤时，病根隐匿于体内，而证候表现于体外，各有固定的征象，如果观察不细致，往往容易混淆。为什么呢？因为五脏外在对应的征候，大多相似，难以拘泥于单一标准，况且又有兼夹其他脏腑病变、互相影响出入的情况，所以辨证时必须预先明确。现在概括其要点，大约有以下几个方面：一是体现在经络循行的部位，如太阳经、少阴经行于身体背部，阳明经、太阴经行于身体前面，少阳经、厥阴经行于身体侧面；二是体现在气化功能所充养的部位，如脾主四肢和口唇，肺主鼻部和肩背部，肝主宗筋、乳头和眼睛，肾主前后二阴、腰脊和耳朵，心主面部和舌头；三是体现在脏气的功能作用上，如肝主疏泄，心主神明，肺主呼气，肾主纳气，脾主中焦，主持全身气机的升降；四是体现在脏气所主管的组织形体上，如肝主筋，心主脉，脾主肌肉，肺主皮毛，肾主骨；五是体现在面色及其对应部位，五色即肝青、心赤、脾黄、肺白、肾黑；对应部位即心对应额头、肾对应下巴、脾对应鼻准、肺对应右颊、肝对应左颊，以及《灵枢》中所叙述的面部色部划分。用这几点相互印证考察，病的所在之处，应当没有遗漏了。但其中尤其以脏气的功能作用为主，正如经典所说，审察病机，不要违背气化的适宜规律。观察前后数日证候的递变情况，判断其病机属于哪一脏，就可以清楚地知道疾病归属于哪一脏了。凡是五脏真气自发的病变，没有不发生相乘相克关系的，比如肝病传脾（木克土），或者脾虚被肝所乘，都是先发病的脏其证候先出现，后发病的脏其证候后出现。《内经》说：“肾气乘袭心气，是心先发病，肾气随后应验”，面色变化也是如此。说的就是这个道理。所以，诊察外感病，必须明白五行的性情及其功能的正常与异常变化；诊察内伤病，必须明白五脏的性情及其功能的正常与异常变化。
For external pathogenic factors (Wai Xie) attacking the exterior, one should discuss solely based on the site of the pathogen's invasion, without necessarily involving the disturbance of internal Zang-organ Qi. Even if the disease persists for a long time and the Zang-organ Qi is disturbed and burdened, the primary focus remains on the site invaded by the pathogen; where the disease lies, there the symptoms manifest, making it easy to identify. However, when Zang-organ Qi is internally injured, the pathology hides within while the manifestations appear externally, each having fixed patterns. If not observed carefully, confusion often arises. Why? Because the external signs corresponding to the Five Zang organs are often similar, making it difficult to adhere rigidly to single criteria. Moreover, there are cases involving multiple Zang organs interacting and influencing each other, so differentiation must be pre-established. Summarizing the essentials, there are several aspects: First, the sites traversed by the meridians, such as the Taiyang (Greater Yang) and Shaoyin (Lesser Yin) meridians running along the posterior body, the Yangming (Bright Yang) and Taiyin (Greater Yin) meridians running along the anterior body, and the Shaoyang (Lesser Yang) and Jueyin (Terminal Yin) meridians running along the lateral body. Second, the sites nourished by Qi transformation, such as the Spleen governing the four limbs and lips, the Lung governing the nose and shoulder-back, the Liver governing the sinews (Jin), nipples, and eyes, the Kidney governing the two yin openings, waist-spine, and ears, and the Heart governing the face and tongue. Third, the functional roles of Zang-organ Qi, such as the Liver governing dispersion and drainage (Shu Xie), the Heart governing the Spirit (Shen Ming), the Lung governing exhalation, the Kidney governing inhalation (Na Qi), and the Spleen governing the Middle Jiao and regulating the ascending and descending of all Qi. Fourth, the tissues governed by Zang-organ Qi, such as the Liver governing sinews, the Heart governing vessels (Mai), the Spleen governing muscles, the Lung governing skin and hair, and the Kidney governing bones. Fifth, facial colors and their corresponding regions: the five colors are Liver-green, Heart-red, Spleen-yellow, Lung-white, and Kidney-black; the regions are Heart-forehead, Kidney-chin, Spleen-nose tip, Lung-right cheek, Liver-left cheek, as well as the facial color regions described in the *Ling Shu*. By cross-referencing these points, the location of the disease will be revealed without omission. Among these, the functional role of Zang-organ Qi is particularly important, as stated in the classics: "Examine the pathogenesis, do not miss the appropriateness of Qi." By observing the progressive changes in symptoms over several days, one can determine which Zang organ the pathogenesis belongs to, thereby clearly identifying the affected Zang. When the true Qi of any of the Five Zang organs is diseased spontaneously, mutual overcoming (Cheng Ke) invariably occurs. For example, Liver disease overcoming the Spleen, or Spleen deficiency being overcome by the Liver, always presents with symptoms of the initially diseased Zang first, followed by those of the subsequently affected Zang. The *Nei Jing* states: "When Kidney Qi overcomes Heart Qi, the Heart is diseased first, and the Kidney responds accordingly"; this applies to facial colors as well. This is what is meant. Therefore, when examining external contraction diseases, one must understand the nature of the Five Elements and the normal and abnormal variations of their functions; when examining internal injury diseases, one must understand the nature of the Five Zang organs and the normal and abnormal variations of their functions.