四肢为诸阳之本。脾实主之。然有上下左右内外之分焉。尝观经脉篇。手之三阴。从脏走手。手之三阳。从
手走头。阳行于外。阴行于内。阳则自下而上。阴则自上而下。析而言之。左为阳。右为阴。上为阳。下为阴。手
臂之在外者为阳。在内者为阴。自肩至肘曰 。自肘至腕曰臂。臂下谓之掌。掌下谓之指。其大指曰拇指。
其次指曰食指。内属太阴。外属阳明。其中指曰将指。其屈而不伸者。曰无名指。内属厥阴。外属少阳。其小
者。曰小指。内属少阴。外属太阳。此皆经络之行。即部位之分也。推而论之。男女有左右逆从之异。经络有
上下标本之殊。病症有内外浅深之辨。望之之法。可弗深究其理哉。以形言之。则形盛为有余。形瘦为不
足。手之壅肿者为实。手之枯细者为虚。左右偏枯曰偏风。手指堕落曰疠风。手掌肿无纹。曰阴虚气绝。手
背肿至腕。曰阳虚气结。此皆以形言也。以容言之。则强者。病气实。痿者。形气虚。撒手者。阳气外脱。握手者。
阴邪内伏。手之伸者。病在阳。手之屈者。病在阴。屈不易伸。伸不易屈者。阴阳交合。阴阳俱病也。屈而不伸。
其病在筋。伸而不屈。其病在骨。汗漏不止。四肢微急者。亡阳之证。小腹急痛。手足拘挛者。将死之容。挛急
转筋者。邪气实而伤于寒。弛纵不收者。正气虚而因于热。螈 不定者。筋脉相引而难瘳。振摇不定者。血
气俱亏而可疗。两手不举者。脾实。四肢不收者。脾虚。掣衣扬手者。烦躁犹可解。循衣摸床者。实热已难除。
叉手冒心者。血液大亏。交手目瞀者。肺病臂厥。捶胸者。胀闷之状。拒按者。疼痛之容。手如数物者。风痫。手
不欲动者。脾亏。指不用者。属脉。臂不遂者。为痹。手足 习者。肝绝之形。手足 曳者。风懿之状。此皆以容
言也。于是合形容而诊之。按经络而验之审其寒温。察其部位。参四诊以究同异。分三因而辨本标。病症
之殊。疗治之变。庶乎知所适从矣。
四肢是诸阳经的根本。由脾脏所主司。然而，四肢又有上下、左右、内外之分野。我曾研读《经脉篇》，其中记载：手部的三条阴经，从内脏走向手部；手部的三条阳经，从手部走向头部。阳气运行于体表外部，阴气运行于体内内部。阳气自下向上运行，阴气自上向下运行。进一步分析而言，左侧属阳，右侧属阴；上部属阳，下部属阴。手臂在外侧的部分属阳，在内侧的部分属阴。从肩部到肘部称为“臑”（nào）；从肘部到腕部称为“臂”；前臂下方称为“掌”；手掌下方称为“指”。其中大拇指称为“拇指”；第二指称为“食指”，内侧归属于太阴经，外侧归属于阳明经；中指称为“将指”；弯曲时不能伸直的那根手指，称为“无名指”，内侧归属于厥阴经，外侧归属于少阳经；最小的那根手指称为“小指”，内侧归属于少阴经，外侧归属于太阳经。这些都是经络的循行路线，也就是部位的划分。推而广之，男女在左右逆顺方面存在差异，经络有上下标本的不同，病症有内外浅深的区别。望诊的方法，怎能不深入探究其中的道理呢？
从形态来看，形体壮盛属于有余（实证），形体消瘦属于不足（虚证）。手部肿胀壅滞的属实证，手部干枯细小的属虚证。身体一侧偏瘫枯瘦称为“偏风”；手指脱落称为“疠风”（麻风病）。手掌肿胀且无纹理，称为阴虚气绝；手背肿胀延伸至手腕，称为阳虚气结。这些都是通过形态来判断的。
从神色姿态来看，手部有力者，病邪气实；手部痿软无力者，形气虚弱；手自然张开者，是阳气外脱的表现；手握拳紧握者，是阴邪内伏的表现。手向外伸展者，病在阳分；手向内屈曲者，病在阴分。既难以伸直又难以屈曲者，是阴阳交合，阴阳两经均患病。屈而不能伸直，病在筋；伸而不能屈曲，病在骨。汗出不止，四肢轻微拘急的，是亡阳的证候。小腹急痛，手足拘挛的，是将死的征象。筋脉拘急转筋的，是邪气实且受寒所致；肢体弛缓纵散不收的，是正气虚且因热所致。肌肉跳动不定者，是筋脉相互牵引而难治愈；震颤摇动不定者，是气血俱亏但尚可治疗。双手不能举起的，是脾实；四肢不能收持的，是脾虚。抓衣摸床扬手的，烦躁尚可以解除；循衣摸床（无意识地抓弄衣物和床沿）的，实热已难以清除。两手交叉护住心口的，是血液大亏；两手交叉且目视昏花的，是肺病导致的手臂厥逆。捶打胸口的，是胀闷的症状；拒绝按压的，是疼痛的表现。手像数东西一样的，是风痫；手不想动的，是脾亏；手指不能使用的，属于脉病；手臂不能随意运动的，是痹证。手足颤抖习习的，是肝绝的形态；手足拖曳无力的，是风懿（中风失语或瘫痪）的状态。这些都是通过神色姿态来判断的。
于是结合形态与神色来诊察，按照经络来验证，审察其寒温属性，观察其部位，参考望、闻、问、切四诊以探究同异，区分三因（内因、外因、不内外因）以辨别本标。这样对于病症的差异和治疗的变化，大概就知道该遵循什么原则了。
The four limbs are the root of all Yang meridians. They are governed by the Spleen (Zang-Fu organ). However, they are divided into upper and lower, left and right, interior and exterior regions. I have studied the *Jing Mai Pian* (Chapter on Meridians), which states: The three Yin meridians of the hand travel from the Zang organs to the hands; the three Yang meridians of the hand travel from the hands to the head. Yang Qi circulates in the exterior, while Yin Qi circulates in the interior. Yang moves upward from below, and Yin moves downward from above. Analyzing further, the left side is Yang, and the right side is Yin; the upper part is Yang, and the lower part is Yin. The lateral aspect of the arm is Yang, and the medial aspect is Yin. From the shoulder to the elbow is called "Nao" (upper arm); from the elbow to the wrist is called "Bi" (forearm); below the forearm is the "Zhang" (palm); below the palm are the "Zhi" (fingers). The large finger is called "Mu Zhi" (thumb); the second finger is called "Shi Zhi" (index finger), internally connected to the Taiyin meridian and externally to the Yangming meridian; the middle finger is called "Jiang Zhi"; the finger that bends but does not extend is called "Wu Ming Zhi" (ring finger), internally connected to the Jueyin meridian and externally to the Shaoyang meridian; the smallest finger is called "Xiao Zhi" (little finger), internally connected to the Shaoyin meridian and externally to the Taiyang meridian. These are the pathways of the meridians and the divisions of the body parts. Extending this logic, there are differences in left-right reversal between men and women, distinctions in upper-lower origin and branch among meridians, and differentiations in interior-exterior depth among diseases. How can the method of inspection fail to deeply investigate these principles?
Speaking of form, a robust physique indicates excess (Shi syndrome), while a emaciated physique indicates deficiency (Xu syndrome). Swelling and fullness of the hand indicate excess; dryness and thinness of the hand indicate deficiency. Hemiplegia or withering of one side of the body is called "Pian Feng" (hemiplegia); falling off of fingers is called "Li Feng" (leprosy). Swelling of the palm without skin lines indicates Yin deficiency and exhaustion of Qi; swelling of the dorsum of the hand extending to the wrist indicates Yang deficiency and stagnation of Qi. These are judgments based on form.
Speaking of demeanor and posture, strength in the hand indicates excess pathogenic Qi; flaccidity indicates deficiency of both form and Qi. An open hand indicates external collapse of Yang Qi; a clenched fist indicates internal entrapment of Yin pathogens. Hands extended outward indicate disease in the Yang aspect; hands flexed inward indicate disease in the Yin aspect. Difficulty in both extending and flexing indicates interaction of Yin and Yang, implying disease in both aspects. Inability to extend but ability to flex indicates disease in the sinews; inability to flex but ability to extend indicates disease in the bones. Unceasing sweating with slight stiffness of the four limbs is a sign of collapse of Yang. Urgent pain in the lower abdomen with spasm of hands and feet is a sign of impending death. Spasms and tendon retraction indicate excess pathogenic Qi due to cold; flaccidity and inability to hold objects indicate deficiency of healthy Qi due to heat. Twitching muscles indicate difficult-to-cure traction of sinews and vessels; trembling and shaking indicate deficiency of both Blood and Qi but are treatable. Inability to raise both hands indicates Spleen excess; inability to control the four limbs indicates Spleen deficiency. Grasping clothes and waving hands indicates irritability, which is still resolvable; groping at clothes and bedrails indicates severe excess-heat, which is difficult to clear. Crossing hands over the heart indicates severe depletion of Blood; crossing hands with blurred vision indicates Lung disease leading to arm Jue-ni (reversal). Beating the chest indicates distension and oppression; refusal to be pressed indicates pain. Counting-like movements of the hand indicate Wind Epilepsy; reluctance to move the hand indicates Spleen deficiency; dysfunction of the fingers belongs to vessel pathology; inability to move the arm freely indicates Bi syndrome (obstruction); trembling of hands and feet indicates Liver exhaustion; dragging of hands and feet indicates Feng Yi (stroke with paralysis/aphasia). These are judgments based on demeanor.
Thus, by combining form and demeanor for diagnosis, verifying according to meridians, assessing cold and heat, observing locations, consulting the Four Diagnostic Methods to explore similarities and differences, and distinguishing the Three Causes to identify root and branch, one can understand how to proceed with treatment amidst varying diseases and therapeutic changes.