尝考内经。阳气起于足五趾之表。阴气起于足五趾之里。足之三阳。从头至足。足之三阴。从足走腹。阳行
于外。阴行于内。阳则自上而下。阴则自下而上。析而言之。左为阳。右为阴。上为阳。下为阴。足之在外者为
阳。在内者为阴。自臀至膝。曰髀。自膝至踝。曰胫。踝下谓之跗。跗前谓之趾。其大趾。则少阳、阳明、厥阴、太阴
之所行。其次趾、中趾。则阳明之所行。其次于小趾之次趾。则少阳之所行。其小趾。则太阳。少阴之所行。此
皆经络之辨。部位之分也。望之之法。可弗深究其形容哉。以形言。则形盛为有余。形瘦为不足。胫肿跗肿
者。水气之实。胫枯脚小者。脾胃之虚。胫有大小者。肾壅偏枯。股无生肉者。脾虚气竭。足下平满者。伤肾之
绝征。脚底先穿者。疠风之败证。十指堕落者。筋死。十趾不用者。经病。两腿消瘦。曰肾消。独膝肿大。曰鹤膝。
足肿至踝。曰阳虚气结。脚肿上胫。曰香港脚逆冲。身体羸瘦。独足肿大者。营卫俱微。足趺壅肿。两膝如斗者。
胃气欲绝。此皆以形言也。以容言。则屈者为阴。伸者为阳。强者邪气实。痿者形气虚。拘急者。寒邪。纵缓者。
热疾。螈 者。筋脉相引。振掉者。血气俱虚。屈伸不能者。筋将惫。屈伸不利者。肾已亏。屈而不伸者。病在筋。
伸而不屈者。病在骨。阴缓而阳急者。阳跷病。阳缓而阴急者。阴跷病。跌蹶能前不能却者。太阳经之伤。
跛或左而或右者。风寒湿之病。转筋者。寒邪在筋。掣节者。寒邪在节。足纵而不任地者。大经空虚。足摇而
不任身者。骨髓枯减。足不收者。脾气虚。足不举者。脾气实。扬手掷足者。烦燥。逾垣上屋者。怒狂。筋缓不能
行者。肝劳。弃衣而狂走者。胃实。立不能坐。坐不能起者。阴阳交合。阴阳俱病也。此皆以容言也。合形容而
视之。审经络而辨之。验其足之寒温。切其脉之动静。参以四诊。究其三因。而病症之变。标本之殊。亦可知
其大略矣。
我曾考证《内经》。阳气起始于足部五个脚趾的表面，阴气起始于足部五个脚趾的深处。足部的三条阳经，从头走向足；足部的三条阴经，从足走向腹部。阳气运行于体表，阴气运行于体内。阳气自上而下运行，阴气自下而上运行。进一步分析来说，左侧为阳，右侧为阴；上部为阳，下部为阴。足部在外侧的为阳，在内侧的为阴。从臀部到膝盖，称为“髀”（大腿）；从膝盖到脚踝，称为“胫”（小腿）；脚踝下方称为“跗”（足背）；跗前称为“趾”。其中，大脚趾，是少阳经、阳明经、厥阴经、太阴经所经过的部位；其次趾和中趾，是阳明经所经过的部位；其次是位于小趾旁边的次趾，是少阳经所经过的部位；小脚趾，是太阳经和少阴经所经过的部位。这些都是经络的辨别和部位的区分。望诊的方法，能不深入研究其形态吗？从形态而言，形体壮盛属于有余，形体消瘦属于不足。小腿肿胀、足背肿胀的，是水气实证；小腿枯瘦、脚小的，是脾胃虚证；小腿粗细不一的，是肾气壅滞或偏瘫；大腿没有生肉的，是脾气虚弱、气力耗尽；足底平坦饱满的，是损伤肾脏的绝症征兆；脚底先出现溃烂穿孔的，是麻风病的败坏证候；十个脚趾脱落的，是筋死；十个脚趾不能活动的，是经病；两条腿消瘦的，称为“肾消”；只有膝盖肿大的，称为“鹤膝”；足部肿胀直到脚踝的，称为阳虚气结；脚部肿胀向上蔓延至小腿的，称为香港脚逆冲；身体羸弱消瘦，唯独足部肿大的，是营卫俱微；足背壅肿，两个膝盖像斗一样突出的，是胃气欲绝。这些都是从形态而言。从姿态而言，弯曲的为阴，伸展的为阳；强直的是邪气实，痿软的是形气虚；拘挛紧急的是寒邪，纵缓松弛的是热疾；抽搐牵引的是筋脉相引，震颤动摇的是血气俱虚；屈伸不能的是筋将衰竭；屈伸不利的是肾已亏损；屈而不能伸的，病在筋；伸而不能屈的，病在骨；内侧弛缓而外侧紧急的是阳跷脉病；外侧弛缓而内侧紧急的是阴跷脉病；跌蹶者能向前但不能向后的，是太阳经受伤；跛行或左或右的，是风寒湿之病；转筋的是寒邪在筋；牵掣关节的是寒邪在节；足部纵缓不能着地的，是大经空虚；足部摇动不能支撑身体的，是骨髓枯减；足部收不住的，是脾气虚；足部举不起来的，是脾气实；扬手掷足的是烦躁；翻墙爬屋的是怒狂；筋缓不能行走的是肝劳；扔掉衣服疯狂奔跑的是胃实；站立不能坐下，坐下不能站起的，是阴阳交合，阴阳都患病了。这些都是从姿态而言。综合形态和姿态来观察，审察经络来辨别，验证足部的寒温，切按脉搏的动静，参考四诊，探究三因，那么病症的变化、标本的差异，也可以知道大概了。
I have examined the *Neijing* (Inner Canon). Yang Qi originates at the exterior of the five toes of the foot, and Yin Qi originates at the interior of the five toes of the foot. The three Yang meridians of the foot run from the head to the foot; the three Yin meridians of the foot run from the foot to the abdomen. Yang moves on the exterior, and Yin moves on the interior. Yang moves from top to bottom, and Yin moves from bottom to top. Analyzing further: the left is Yang, the right is Yin; the upper is Yang, the lower is Yin. The lateral aspect of the foot is Yang, and the medial aspect is Yin. From the buttocks to the knee is called "Bi" (thigh); from the knee to the ankle is called "Jing" (shin/calf); below the ankle is called "Fu" (dorsum of foot); anterior to the dorsum is called "Zhi" (toe). Among these, the big toe is traversed by Shaoyang, Yangming, Jueyin, and Taiyin meridians; the second and middle toes are traversed by the Yangming meridian; the toe adjacent to the little toe is traversed by the Shaoyang meridian; the little toe is traversed by the Taiyang and Shaoyin meridians. These are distinctions of meridians and divisions of locations. In the method of observation, can one fail to deeply investigate their descriptions? Speaking of form: robust form indicates excess; emaciated form indicates deficiency. Swelling of the shin and dorsum indicates excess of water qi; withered shins and small feet indicate deficiency of Spleen and Stomach. Shins of unequal size indicate Kidney obstruction or hemiplegia; thighs without flesh indicate Spleen Qi deficiency and exhaustion. A flat and full sole indicates a sign of fatal Kidney injury; perforation starting from the sole indicates a deteriorating stage of Leprosy (Lifeng); falling off of ten toes indicates death of tendons; inactivity of ten toes indicates disease of the meridians; emaciation of both legs is called "Kidney Xiao" (diabetes-like wasting); isolated swelling of the knees is called "Crane Knee"; swelling of the foot extending to the ankle is called Yang deficiency with Qi stagnation; swelling of the foot ascending to the shin is called Hongxiangjiao counter-flowing attack; emaciation of the body with isolated swelling of the feet indicates deficiency of both Ying and Wei; swelling of the dorsum with knees protruding like bowls indicates impending extinction of Stomach Qi. These are all based on form. Speaking of posture: flexion is Yin, extension is Yang; rigidity indicates excess of pathogenic factors; flaccidity indicates deficiency of form and Qi; spasm and tension indicate Cold pathogen; laxity indicates Heat disease; convulsive traction indicates pulling of tendons and vessels; tremor and shaking indicate deficiency of both Blood and Qi; inability to flex or extend indicates impending exhaustion of tendons; difficulty in flexion and extension indicates deficiency of the Kidney; inability to extend after flexion indicates disease in the tendons; inability to flex after extension indicates disease in the bones; laxity on the medial side and tension on the lateral side indicates disease of the Yang Qiao vessel; laxity on the lateral side and tension on the medial side indicates disease of the Yin Qiao vessel; inability to step backward while being able to step forward indicates injury to the Taiyang meridian; limping alternating between left and right indicates Wind-Cold-Dampness disease; muscle cramping indicates Cold pathogen in the tendons; joint pulling indicates Cold pathogen in the joints; foot laxity unable to bear weight on the ground indicates emptiness of the great meridians; foot trembling unable to support the body indicates depletion of bone marrow; inability to control the foot indicates Spleen Qi deficiency; inability to lift the foot indicates Spleen Qi excess; throwing hands and kicking feet indicates irritability; climbing walls and roofs indicates manic anger due to excess; tendon laxity preventing walking indicates Liver labor; discarding clothes and running wildly indicates Stomach excess; inability to sit while standing, or stand while sitting, indicates intermingling of Yin and Yang, meaning both are diseased. These are all based on posture. Observing form and posture together, examining meridians to distinguish conditions, verifying the cold or warmth of the feet, palpating the movement or stillness of the pulse, consulting the Four Diagnostic Methods, and investigating the Three Causes, one can understand the general outline of changes in diseases and differences between root and branch manifestations.