此篇论营血之专行于经隧，循环无端，而成十二经脉，须与第一篇参看，其理益明。
黄帝曰∶营气之道，内谷为宝。谷入于胃，乃传之肺，流溢于中，布散于外，精专者行于经隧，常营无
已，终而复始，是谓天地之纪。故气从太阴出，注手阳明，上行注足阳明，下行至跗
上，注大指间，与太阴合，上行抵髀。从脾注心中，循手少阴出腋下臂，注小指合手太阳，上行乘腋出 内，
注目内 ，上巅下项，合足太阳，循脊下尻，下行注小指之端，循足心注足少阴，上行注肾，从肾注心，外
散于胸中。循心主脉出腋下臂，出两筋之间，入掌中，出中指之端，还注小指次指之端，合手少
阳，上行注膻中，散于三焦，从三焦注胆，出胁注足少阳，下行至跗上，复从跗注大指间，合足厥阴，上行至
肝，从肝上注肺，上循喉咙，入颃颡之窍，究于蓄门。其支别者，上额循巅下项中，循脊入 ，是督脉也，络
阴器，上过毛中，入脐中，上循腹里，入缺盆，下注肺中，复出太阴。此营气之所行也，逆顺之常也。
此篇论营卫之所由生，及三焦生化之原理。凡针法皆借营卫以为用，如不明营卫循行与三焦相关之理，
则区区毫芒之针，如何发生效力。且所谓刺营无伤卫，刺卫无伤营者，果如所指，又果何以措手耶。
黄帝问于岐伯曰∶人焉受气？阴阳焉会？何气为营？何气为卫？营安从生？卫于焉会？老壮不同气，阴阳
异位，愿闻其会。岐伯答曰∶人受气于谷，谷入于胃，以传与肺，五脏六腑，皆以受气，其清者为营，浊者为
卫，营在脉中，卫在脉外，营周不休，五十而复大会。阴阳相贯，如环无端。卫气行于阴二十五
度，行于阳二十五度，分为昼夜，故气至阳而起，至阴而止。故曰∶日中而阳陇为重阳，夜半而阴陇为重阴。
故太阴主内，太阳主外，各行二十五度，分为昼夜。夜半为阴陇，夜半后而为阴衰，平旦阴尽而阳受气矣。日
中为阳陇，日西而阳衰，日入阳尽而阴受气矣。夜半而大会，万民皆卧，命曰合阴，平旦阴尽而阳
受气，如是无已，与天地同纪。
黄帝曰∶老人之不夜瞑者，何气使然？少壮之人不昼瞑者，何气使然？岐伯答曰∶壮者之气血盛，其肌肉
滑，气道通，营卫之行，不失其常，故昼精而夜瞑。老者之气血衰，其肌肉枯，气
道涩，五脏之气相搏，其营气衰少而卫气内伐，故昼不精，夜不瞑。
黄帝曰∶愿闻营卫之所行，皆何道从来？岐伯答曰∶营出于中焦，卫出于下焦。黄帝曰∶愿闻三焦之所
出。岐伯答曰∶上焦出于胃上口，并咽以上贯膈而布胸中，走腋，循太阴之分而行，还至阳明，上至舌，下足
阳明，常与营俱行于阳二十五度，行于阴亦二十五度一周也，故五十度而复大会于手太阴矣。
黄帝曰∶人有热饮食下胃，其气未定，汗则出，或出于面，或出于背，或出于身半，其不循卫气之道而出
何也？岐伯曰∶此外伤于风，内开腠理，毛蒸理泄，卫气走之，固不得循其道，此气 悍滑疾，见开而出，故
不得从其道，故命曰漏泄。
黄帝曰∶愿闻中焦之所出。岐伯答曰∶中焦亦并胃中，出上焦之后，此所受气者，泌糟粕，蒸津液，化其
精微，上注于肺脉，乃化而为血，以奉生身，莫贵于此，故独得行于经隧，命曰营气。黄帝曰∶夫血之与气，
异名同类，何谓也？岐伯答曰∶营卫者，精气也。血者，神气也。故血之与气，异名同类焉。故夺
血者无汗，夺汗者无血，故人生有两死而无两生。
黄帝曰∶愿闻下焦之所出。岐伯曰∶下焦者，别回肠，注于膀胱而渗入焉。故水谷者，常并居于胃中，
成糟粕，而俱下于大肠，而成下焦，渗而俱下，济泌别汁，循下焦而渗入膀胱焉。
黄帝曰∶人饮酒，酒亦入胃，谷未熟而小便独先下何也？岐
伯答曰∶酒者，熟谷之液也，其气悍以清，故后谷而入，先谷而
液出焉。黄帝曰∶善。余闻上焦如雾，中焦如沤，下焦如渎，此之谓也。
本篇论述营血专门在经脉中运行，循环往复没有尽头，从而形成十二经脉的循行路线。需要与第一篇结合参看，其中的道理会更加明白。
黄帝说：营气的生成之道，以水谷精微为宝贵。食物进入胃后，进而传送给肺，流溢于体内，布散于体表。其中精纯专一的部分在经脉中运行，常年营运不止，终而复始，这被称为天地的纲纪。因此，气从手太阴肺经发出，注入手阳明大肠经，上行注入足阳明胃经，下行至足背，注入足大趾间，与足太阴脾经相合，上行抵达大腿。从脾脏注入心中，沿手少阴心经出于腋下臂部，注入小指末端与手太阳小肠经相合，上行经过腋下，出于面颊，注目内眦，上行至头顶，再下项部，与足太阳膀胱经相合，沿脊柱下行至尾骶部，下行注入小趾末端，沿足心注入足少阴肾经，上行注入肾脏，从肾脏注入心脏，向外散布于胸中。沿手厥阴心包经出于腋下臂部，出于两筋之间，进入手掌中，出于中指末端，回注无名指末端，与手少阳三焦经相合，上行注入膻中，散布于三焦，从三焦注入胆腑，出于胁肋注入足少阳胆经，下行至足背，又从足背注入足大趾间，与足厥阴肝经相合，上行至肝脏，从肝脏上注于肺，向上沿喉咙，进入鼻咽部的窍道，穷尽于蓄门（会厌）。其分支别出的部分，上行额部，沿头顶下项中，沿脊柱入络，这是督脉，联络阴器，向上经过阴毛处，进入脐中，向上沿腹腔内部，进入缺盆，下行注入肺中，再复出至手太阴肺经。这就是营气的运行规律，也就是逆顺的正常法则。
本篇论述营卫之气产生的来源，以及三焦生化作用的原理。凡是针刺方法都借助营卫之气来发挥作用，如果不明白营卫循行与三焦相关的道理，那么区区毫芒之针，如何能产生疗效。况且所谓“刺营不伤卫，刺卫不伤营”，如果真的像所指的那样，又究竟该如何下手施针呢？
黄帝问岐伯说：人从哪里接受气？阴阳在哪里交会？什么气是营气？什么气是卫气？营气从哪里产生？卫气在哪里交会？老人和壮年人气血不同，阴阳位置各异，希望听听它们交会的道理。岐伯回答说：人接受的气来源于水谷，水谷进入胃中，进而传送给肺，五脏六腑都由此接受气。其中清轻的部分成为营气，重浊的部分成为卫气。营气行于脉中，卫气行于脉外，营气周流不息，运行五十周次后再次大会。阴阳相互贯通，如圆环一样没有端点。卫气在阴分运行二十五周次，在阳分运行二十五周次，以此区分昼夜。所以卫气行至阳分则人觉醒，行至阴分则人入睡。所以说：中午时阳气隆盛称为重阳，半夜时阴气隆盛称为重阴。所以太阴主内守，太阳主外御，各运行二十五周次，以此区分昼夜。半夜时阴气最盛，半夜过后阴气开始衰退，黎明时阴气耗尽而阳气开始受气。中午时阳气最盛，日落时阳气衰退，日落后阳气耗尽而阴气开始受气。半夜时阴阳之气大会，百姓都在睡觉，这叫做“合阴”。黎明时阴气耗尽而阳气受气，如此循环不止，与天地的规律相同。
黄帝说：老年人晚上睡不着觉，是什么气导致的？年轻人白天不睡觉，又是什么气导致的？岐伯回答说：壮年人的气血旺盛，肌肉滑利，气道通畅，营卫的运行不失常态，所以白天精神饱满，晚上能入睡。老年人的气血衰弱，肌肉枯槁，气道涩滞，五脏之气相互搏结，营气衰少而卫气内扰，所以白天精神不振，晚上睡不着。
黄帝说：希望听听营卫之气运行，都是从什么道路出发的？岐伯回答说：营气产生于中焦，卫气产生于下焦。黄帝说：希望听听三焦是从哪里出发的。岐伯回答说：上焦出于胃的上口，并咽而上贯膈肌，散布于胸中，走腋部，沿手太阴肺经的分野而行，返回至手阳明大肠经，上至舌根，下接足阳明胃经，常与营气一起行于阳分二十五周次，行于阴分也是二十五周次为一周，所以运行五十周次后再次在手太阴肺经大会。
黄帝说：人吃了热饮食进入胃中，食物之气尚未定夺，汗就出来了，有的出于面部，有的出于背部，有的出于身体半侧，为什么不沿着卫气运行的道路而出呢？岐伯说：这是因为外部被风邪所伤，内部腠理开泄，毛孔蒸腾，纹理疏泄，卫气随之而走，本来就不能遵循其道，这种气剽悍滑疾，见到腠理开泄就外出，所以不能从其正常通道，因此命名为漏泄。
黄帝说：希望听听中焦是从哪里出发的。岐伯回答说：中焦也在胃中，位于上焦之后，这里所受纳的气，泌别糟粕，蒸化津液，化生精微，上注于肺脉，于是化生为血液，用来供养生命躯体，没有比这更宝贵的了，所以只有它能行于经脉之中，命名为营气。黄帝说：血和气，名称不同但同类，这是什么意思？岐伯回答说：营卫是精气，血是神气。所以血和气，名称不同但同类。所以失血的人不能再发汗，大汗淋漓的人不能再放血，所以人同时面临失血和夺汗两种情况就会死亡，而没有同时获得这两种情况就能生存的道理。
黄帝说：希望听听下焦是从哪里出发的。岐伯说：下焦分别于回肠，注入膀胱并渗入其中。所以水谷常常居住在胃中，变成糟粕，一起下行到大肠，形成下焦的功能，渗滤分离汁液，沿着下焦渗入膀胱。
黄帝说：人喝酒，酒也进入胃中，谷物还没消化完而小便却先排出了，为什么呢？岐伯回答说：酒是熟谷的液体，它的气味剽悍而清轻，所以虽然后于谷物进入胃中，却先于谷物化为液体排出。黄帝说：好。我听说上焦如雾，中焦如沤，下焦如渎，说的就是这种情况。
This chapter discusses how Ying (Nutrient) blood runs exclusively within the meridians, circulating endlessly to form the pathways of the Twelve Meridians. It should be read in conjunction with the first chapter for a clearer understanding of its principles.
The Yellow Emperor said: The way of Ying Qi treasures grain as its essence. When food enters the stomach, it is transmitted to the Lung, overflows internally, and spreads externally. The pure and concentrated portion travels within the Jingmai (Meridians), operating ceaselessly and restarting cyclically; this is called the norm of Heaven and Earth. Thus, Qi emerges from the Hand-Taiyin (Lung) meridian, flows into the Hand-Yangming (Large Intestine) meridian, ascends to flow into the Foot-Yangming (Stomach) meridian, descends to the dorsum of the foot, flows into the space between the big toe, joins with the Foot-Taiyin (Spleen) meridian, and ascends to the thigh. From the Spleen, it flows into the Heart, follows the Hand-Shaoyin (Heart) meridian out through the axilla and arm, flows into the tip of the little finger to join the Hand-Taiyang (Small Intestine) meridian, ascends through the axilla, emerges at the inner canthus, ascends to the vertex, descends to the nape, joins the Foot-Taiyang (Bladder) meridian, follows the spine down to the sacrum, descends to the tip of the little toe, follows the sole to flow into the Foot-Shaoyin (Kidney) meridian, ascends to the Kidney, flows from the Kidney to the Heart, and scatters externally into the chest. Following the Pericardium meridian, it emerges from the axilla and arm, exits between the two tendons, enters the palm, emerges at the tip of the middle finger, returns to flow into the tip of the ring finger, joins the Hand-Shaoyang (Sanjiao) meridian, ascends to the Danzhong (Chest Center), scatters into the Sanjiao (Triple Burner), flows from the Sanjiao to the Gallbladder, emerges from the hypochondrium to flow into the Foot-Shaoyang (Gallbladder) meridian, descends to the dorsum of the foot, again flows from the dorsum into the space between the big toes, joins the Foot-Jueyin (Liver) meridian, ascends to the Liver, flows from the Liver up to the Lung, ascends along the throat, enters the orifice of the Xangsang (Nasopharynx), and reaches the Xumen (Glottis). Its branch diverges, ascending to the forehead, following the vertex down the nape, following the spine into the interior; this is the Du Mai (Governor Vessel), which connects to the genitalia, passes above the pubic hair, enters the umbilicus, ascends along the abdominal interior, enters the Keyuan (Clavicular Fossa), descends to flow into the Lung, and re-emerges into the Hand-Taiyin (Lung) meridian. This is the pathway of Ying Qi, the normal order of reverse and forward circulation.
This chapter discusses the origin of Ying and Wei (Defensive) Qi, and the principles of bio-transformation in the Sanjiao. All acupuncture methods rely on Ying and Wei for their efficacy. If one does not understand the relationship between the circulation of Ying/Wei and the Sanjiao, how can mere needle pricks produce effects? Furthermore, regarding the principle that "needling Ying does not injure Wei, and needling Wei does not injure Ying," if this is truly the case, how exactly should one proceed?
The Yellow Emperor asked Qibo: Where does man receive Qi? Where do Yin and Yang meet? Which Qi is Ying? Which Qi is Wei? From where does Ying arise? Where does Wei converge? The Qi of the old and the young differs, and Yin and Yang occupy different positions; I wish to hear about their convergence. Qibo replied: Man receives Qi from grain. Grain enters the stomach, is transmitted to the Lung, and all Zang-Fu organs receive Qi from it. The clear part becomes Ying Qi, and the turbid part becomes Wei Qi. Ying Qi moves within the vessels, while Wei Qi moves outside the vessels. Ying Qi circulates without rest, meeting again after fifty cycles. Yin and Yang interpenetrate like a circle without end. Wei Qi travels through the Yin twenty-five times and through the Yang twenty-five times, dividing day and night. Thus, when Qi reaches Yang, the person awakens; when it reaches Yin, the person rests. Therefore, it is said: At noon, Yang is abundant, constituting Extreme Yang; at midnight, Yin is abundant, constituting Extreme Yin. Taiyin governs the interior, and Taiyang governs the exterior, each traveling twenty-five times to divide day and night. Midnight is the peak of Yin; after midnight, Yin declines. At dawn, Yin is exhausted, and Yang begins to receive Qi. Noon is the peak of Yang; at sunset, Yang declines. After sunset, Yang is exhausted, and Yin begins to receive Qi. At midnight, there is a great convergence; all people sleep, called "He Yin" (Yin Union). At dawn, Yin is exhausted, and Yang receives Qi. This cycle continues endlessly, mirroring the rhythms of Heaven and Earth.
The Yellow Emperor said: Why do the elderly not sleep well at night? Why do the young and strong not sleep during the day? Qibo answered: In vigorous people, Qi and Blood are abundant, muscles are smooth, and Qi pathways are unobstructed. The movement of Ying and Wei remains normal, so they are alert during the day and sleep soundly at night. In the elderly, Qi and Blood decline, muscles become withered, and Qi pathways become obstructed. The Qi of the five Zang organs clashes, Ying Qi becomes deficient, and Wei Qi attacks inwardly. Thus, they lack alertness during the day and cannot sleep at night.
The Yellow Emperor said: I wish to know the path along which Ying and Wei travel and where they originate. Qibo answered: Ying originates from the Middle Jiao, and Wei originates from the Lower Jiao. The Yellow Emperor said: I wish to know the origins of the Sanjiao. Qibo answered: The Upper Jiao emerges from the upper orifice of the Stomach, accompanies the pharynx upward, pierces the diaphragm, and distributes in the chest. It travels via the axilla, follows the distribution of the Hand-Taiyin, returns to the Hand-Yangming, ascends to the tongue, and descends to the Foot-Yangming. It usually travels with Ying Qi twenty-five times through Yang and twenty-five times through Yin in one cycle, thus meeting again at the Hand-Taiyin after fifty cycles.
The Yellow Emperor said: When a person consumes hot food and drink, before the Qi has settled, sweat appears—sometimes on the face, sometimes on the back, sometimes on half the body. Why does it not follow the pathway of Wei Qi? Qibo said: This is due to external wind injury causing internal opening of the Couli (pores). The pores steam and the skin texture leaks. Wei Qi rushes forth, unable to follow its proper path. Because this Qi is fierce, slippery, and rapid, it exits upon seeing an opening, hence deviating from its channel. This condition is named Louxi (Leakage).
The Yellow Emperor said: I wish to know the origin of the Middle Jiao. Qibo answered: The Middle Jiao also resides in the Stomach, emerging after the Upper Jiao. The Qi received here separates dregs, steams fluids, transforms them into essences, and pours them upward into the Lung vessels. There, they transform into Blood to nourish the living body. Nothing is more precious than this; therefore, only it travels within the Jingmai, and is named Ying Qi. The Yellow Emperor said: Blood and Qi have different names but are of the same category. What does this mean? Qibo answered: Ying and Wei are Essence Qi. Blood is Spirit Qi. Thus, Blood and Qi are of the same category despite different names. Therefore, those who lose Blood should not undergo sweating therapy, and those who suffer excessive sweating should not undergo bloodletting. A person faces death from both conditions simultaneously, but cannot survive by gaining both simultaneously.
The Yellow Emperor said: I wish to know the origin of the Lower Jiao. Qibo said: The Lower Jiao separates from the ileum, pours into the Bladder, and seeps in. Thus, water and grain often reside in the Stomach, turn into dregs, and descend together to the Large Intestine, forming the function of the Lower Jiao. They filter and separate juices, flowing along the Lower Jiao to seep into the Bladder.
The Yellow Emperor said: When a person drinks wine, it enters the Stomach. Why does urine exit alone before the grain is fully digested? Qibo answered: Wine is the liquid of cooked grain. Its Qi is fierce and clear. Although it enters the Stomach after grain, it transforms into liquid and exits before the grain. The Yellow Emperor said: Excellent. I have heard that the Upper Jiao is like mist, the Middle Jiao like foam, and the Lower Jiao like a ditch. This is what is meant.