心主身之血脉。肺主身之皮毛。皮毛者。肺之合也。太阴者。肺也。行气温于皮毛者也。若析而论之。则经络
之行。部位之分。又各有所主。何则。督行于背。任行于腹。手之三阴。从脏走手。手之三阳。从手走头。足之三
阳。从头走足。足之三阴。从足走腹。阴行于内。阳行于外。视其经络。分其部位。其经之血气盛。则充肤热肉。
血独盛。则渗灌皮肤。生毫毛。彼言十二经之气血多少者。论其常。此言充肤热肉生毫毛者。察其变。毫毛
有长短粗细美恶。由气血有多少清浊盛衰。是皆因人而异者也。其因病而变。又各不同。毫毛毕直者。风
寒外感之证。毫毛折落者。肺脏内绝之形。洒洒然毛耸者。太阳中 。洒洒然毛立者。虚邪中人。毛焦者。寒
热在于皮肌。毛悴者。情志伤其脏腑。毛败者。肺热而金受火之克。毛枯者。疳病而金乏土之生。此皆诊法
之略也。由是而观。当以粗而长者为血多。细而短者为血少。耸与直立为邪实。焦与枯败为正虚。悴同折
主死。美而泽主生。善诊者。察毫毛。观气色。听声音。参脉证。可以知其吉凶矣。若夫毛窍之多寡。或言八万
四千。或言十万八千。而究竟不知几万几千。即能知其几万几千。亦何取乎几万几千。夫经络之曲折。病
证之纷纭。古圣述之于前。昔贤验之于后。虽西医剖视。不能如此其详。而况针穴之微妙。石药之功能。断
非技巧所能窥者乎。然则今人不逮古圣也远甚。书曰。事不师古。鲜克有济。
心主管全身的血脉。肺主管全身的皮毛。皮毛是肺所合应的部位。太阴经就是肺经，它是运行气并温煦皮毛的经脉。如果细致地分析，那么经络的运行路线和部位的划分，又各自有所主治。为什么呢？督脉行于背部，任脉行于腹部。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。足部的三条阳经，从头走向足部；足部的三条阴经，从足部走向腹部。阴经行于体内，阳经行于体表。观察经络，分辨部位，该经的气血旺盛，就能充盈皮肤、温暖肌肉；血液特别旺盛，就能渗透灌注到皮肤，生长毫毛。那些谈论十二经脉气血多少的人，是在论述其常态；这里所说的充盈皮肤、温暖肌肉、生长毫毛，是在考察其变化。毫毛有长短、粗细、美丑之分，这取决于气血的多少、清浊以及盛衰情况，这些都是因人而异的。因病而发生的改变，又各不相同。毫毛全部竖起直立的，是风寒外感的证候；毫毛折断脱落的，是肺脏内部功能衰竭的表现；毛发战栗耸起的，是太阳经受邪（中）；毛发竖立不宁的，是虚邪侵袭人体；毛发焦枯的，是寒热之邪在皮肤肌肉之间；毛发憔悴的，是情志损伤了脏腑；毛发败坏的，是肺热导致金受火克；毛发干枯的，是疳病导致土不生金。这些都是诊法的概要。由此看来，应当以粗长者为血多，细短者为血少；耸立和直立为邪气实，焦枯和败坏为正气虚；憔悴同折断主死症，美丽润泽主生症。善于诊察的医生，通过观察毫毛，查看气色，聆听声音，参考脉象和证候，就可以知道疾病的吉凶了。至于毛孔的数量，有的说八万四千，有的说十万八千，但究竟不知道是多少万多少千。即使能知道具体数量，又何必执着于这个数目呢？经络的曲折复杂，病证的纷繁多样，古代圣人已在前面阐述，昔日贤人已在后面验证。即使是西医进行解剖观察，也不能像这样详细，更何况针灸穴位的微妙之处和石药（矿物药）的功能作用，绝非凭借技巧所能窥探的呢。然而现在的人远远赶不上古代的圣人。《尚书》说：做事不效法古人，很少能够成功。
The Heart governs the blood vessels of the body. The Lung governs the skin and hair (mao) of the body. Skin and hair are the exterior correspondence of the Lung. The Taiyin meridian is the Lung meridian, which circulates Qi and warms the skin and hair. If analyzed in detail, the pathways of the meridians and the division of regions each have their specific dominions. Why? The Du Mai (Governing Vessel) runs along the back, and the Ren Mai (Conception Vessel) runs along the abdomen. 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. The three Yang meridians of the foot travel from the head to the feet; the three Yin meridians of the foot travel from the feet to the abdomen. Yin meridians run internally, while Yang meridians run externally. By observing the meridians and distinguishing the regions: when the Qi and Blood of a meridian are abundant, they fill the skin and warm the flesh; when Blood is particularly abundant, it permeates the skin and generates hair. Those who discuss the abundance or scarcity of Qi and Blood in the twelve regular meridians are discussing the normal state; what is stated here regarding filling the skin, warming the flesh, and generating hair refers to observing variations. Hair varies in length, thickness, and quality (beauty or ugliness), depending on the quantity, clarity, turbidity, and strength or decline of Qi and Blood. These differences vary from person to person. Changes due to disease also differ. When hair stands straight up entirely, it indicates a syndrome of external contraction by Wind-Cold. When hair breaks off or falls out, it is a sign of internal exhaustion of the Lung organ. When hair shivers and stands up, it indicates pathogenic invasion of the Taiyang channel. When hair stands erect restlessly, it indicates invasion by deficient evil (false pathogens). When hair becomes scorched, it indicates Cold-Heat residing in the skin and muscles. When hair appears withered, it indicates injury to the zang-fu organs by emotional factors. When hair deteriorates, it indicates Lung Heat where Metal is overcome by Fire. When hair becomes dry and brittle, it indicates malnutrition syndrome (Gan disease) where Earth fails to generate Metal. These are the essentials of diagnostic methods. From this perspective, coarse and long hair indicates abundant Blood, while fine and short hair indicates scarce Blood. Erect and upright hair indicates Excess of Evil, while scorched, dry, and deteriorated hair indicates Deficiency of Healthy Qi. Withered and broken hair presages death, while beautiful and lustrous hair presages life. A skilled diagnostician observes the hair, inspects the complexion, listens to the voice, and correlates pulse findings with symptoms to ascertain the prognosis. As for the number of hair follicles, some say eighty-four thousand, others say one hundred eight thousand, yet the exact number remains unknown. Even if one knew the precise number, why would such a figure be significant? The complexity of meridians and the diversity of pathological conditions were described by ancient sages in the past and verified by former worthies in later times. Even Western medical dissection cannot achieve such detail, let alone the subtlety of acupuncture points and the efficacy of mineral medicines (Shi Yao), which certainly cannot be fathomed by mere technical skill. Thus, modern people fall far short of ancient sages. The Book of Documents states: "In affairs, if one does not model oneself on antiquity, few will succeed."