人有四海，十二经水者皆注于海。有髓海，有血海，有气海，有水谷之海。胃者为
水谷之海，其 上在气街，下至三里。冲脉者为十二经之海，其 上在大杼，下出巨虚上下
廉。膻中者为气之海，其 上在柱骨之上下，前在人迎。脑者为髓之海，其 上在其盖
，下在风府。凡此四海者，得顺者生，得逆者败；知调者利，不知调者害。曰∶四海之逆顺
奈何？曰∶气海有余，则气满胸中 ，急息面赤；不足则气少不足以言。血海有余，则
常想其身大怫郁也，然不知其所病；不足则常想其身小狭，然不知其所病。水谷之海有余，
则腹胀满；不足则饥不受谷食。髓海有余，则轻劲多力，自过其度；不足则脑转耳鸣，胫
酸，眩冒目无所见，懈怠安卧。曰∶调之奈何？曰∶审守其 而调其虚实，无犯
其害；顺者得复，逆者必败。
黄帝问曰∶五十营奈何？岐伯对曰∶周天二十八宿，宿三十六分，人气行一周千八分。
人经络上下左右前后二十八脉，周身十六丈二尺，以应二十八宿，漏水下百刻，以分昼夜。
故人一呼脉再动，气行三寸，一吸脉亦再动，气行三寸，呼吸定息，气行六寸。十息脉行六
尺，日行二分。二百七十息，气行十六丈二尺，气行交通于中，一周于身，下水二刻，日行
二十分有奇。五百四十息，气行再周于身，下水四刻，日行四十分有奇。二千七百息，气行
十周于身，下水二十刻，日行五宿二百十分有奇。一万三千五百息，气行五十营于身，水
下百刻，日行二十八宿，漏水皆尽脉已终矣。（王冰曰∶此略而言之也，细言之，则常以
一十周加一分又十分分之六，乃奇分尽也）。所谓交通者，并行一数也。故五十营备，得尽
天地
谓五十营者，五脏皆受气也。（此段旧在经脉根结之末，今移在此。）
曰∶卫气之行，出入之会何如？曰∶岁有十二月，日有十二辰，子午为经，卯酉为纬；
天一面七宿，周天四七二十八宿，房昂为纬，张虚为经；是故房至毕为阳，昂至心为阴。阳
主昼，阴主夜；故卫气之行，一日一夜五十周于身。昼日合于阳二十五周，夜行于阴亦二十
五周，周于五脏（一本作岁）；是故平旦阴气尽，阳气出于目，目张则气行于头，循于项，下
足太阳，循背下至小指端。其散者，分于目，别（一云别于目锐 ），下手太阳，下至手小指外
侧。其散者，别于目锐 ，下足少阳，注小指次指之间。以上循手少阳之分侧，下至小指之
间。别者以上至耳前，合于颔脉，注足阳明，下行至跗上。入足五指之间。其散者从耳，
下手阳明入大指之间。入掌中，直至于足，入足心，出内踝下行阴分，复合于目，故为一周。
是故日行一舍，人气行于身一周与十分身之八；日行二舍，人气行于身三周与十分身之
六；日行三舍，人气行于身五周与十分身之四；日行四舍，人气行于身七周与十分身之
二；日行五舍，人气行于身九周；日行六舍，人气行于身十周与十分身之八；日行七舍，
人气行于身十二周与十分身之六；日行十四舍，人气二十五周于身有奇分与十人身之
四。阳尽于阴，阴受气矣。其始入于阴，常从足少阴注于肾，肾注于心，心注于肺，肺注于
肝，肝注于脾，脾复注于肾，为一周。是故夜行一舍，人气行于身（一云阴脏）一周与十分
脏之八，亦如阳之行二十五周而复会于目。阴阳一日一夜，舍于奇分十分身之四与十分脏
之四（一作二，上文十分脏之八，此言十分脏之四，疑有误）。是故人之所以卧起之时有早
晏者，以奇分不尽故也。
曰∶卫气之在身也，上下往来无已，其候气而刺之奈何？曰∶分有多少，日有长短，春
秋冬夏，各有分理，然后常以平旦为纪，夜尽为始。是故一日一夜，漏水百刻。二十五刻者
，半日之度也。常如是无已，日入而止，随日之长短，各以为纪。谨候
气之所在而刺之。是谓逢时。病在于阳分，必先候其气之加在于阳分而刺之；病在于阴分，
必先候其气之加在于阴分而刺之，谨候其时，病可与期；失时反候，百病不除。
水下一刻，人气在太阳；水下二刻，人气在少阳；
水下三刻，人气在阳明；水下四刻，人气在阴分；
水下五刻，人气在太阳；水下六刻，人气在少阳；
水下七刻，人气在阳明；水下八刻，人气在阴分；
水下九刻，人气在太阳；水下十刻，人气在少阳；
水下十一刻，人气在阳明；水下十二刻，人气在阴分；
水下十三刻，人气在太阳；水下十四刻，人气在少阳；
水下十五刻，人气在阳明；水下十六刻，人气在阴分；
水下十七刻，人气在太阳；水下十八刻，人气在少阳；
水下十九刻，人气在阳明；水下二十刻，人气在阴分；
水下二十一刻，人气在太阳；水下二十二刻，人气在少阳；
水下二十三刻，人气在阳明；水下二十四刻，人气在阴分；
水下二十五刻，人气在太阳。此少半日之度也。
从房至毕一十四度，水下五十刻，半日之度也。从昴至心亦十四度，水下五十刻，
终日之度也。日行一舍者，水下三刻与十（《素问》作七）分刻之四。大要常以日加之
于宿上也，则知人气在太阳。是故日行一宿，人气在三阳与阴分。常如是无已，与天地同纪
，纷纷HT HT （普巴切），终而复始。一日一夜，水行百刻而尽矣。故曰刺实者刺
其来，刺虚者刺其去，此言气之存亡之时，以候虚实而刺之也。
人有四海，十二经水（人体内的十二条主要经脉）都注入海中。有髓海，有血海，有气海，有水谷之海。胃是水谷之海，其上在气街穴，下至足三里穴。冲脉是十二经之海，其上在大杼穴，下出上巨虚和下巨虚穴。膻中是气之海，其上在柱骨（脊柱）的上下，前在人迎穴。脑是髓之海，其上在其头顶盖部，下在风府穴。这四海，顺应则生，违背则败；懂得调摄则有利，不懂调摄则有害。问：四海的逆顺情况是怎样的？答：气海有余，则胸中气满，呼吸急促，面色发红；不足则气少，说话无力。血海有余，则常觉得身体庞大，郁闷不畅，但不知病在哪里；不足则常觉得身体细小狭小，但不知病在哪里。水谷之海有余，则腹胀满；不足则虽觉饥饿却无法进食。髓海有余，则身轻劲健，力气过大，超过正常限度；不足则头晕耳鸣，小腿酸软，眩晕眼花，视物不清，倦怠嗜卧。问：如何调治？答：仔细审察其所在部位并调治其虚实，不要造成危害；顺应者得以恢复，逆乱者必然失败。
黄帝问道：五十营是怎么回事？岐伯回答说：周天有二十八宿，每宿三十六分，人气运行一周为一千八百分。人的经络上下左右前后共二十八脉，周身长十六丈二尺，以对应二十八宿，漏水滴下一百刻，用来划分昼夜。所以人每呼一次脉跳动两次，气行三寸，每吸一次脉也跳动两次，气行三寸，呼吸之间停顿片刻，气行六寸。十次呼吸脉行六尺，日行二分。二百七十息，气行十六丈二尺，气在体内交通运行，一周于身，水下两刻，日行二十多分。五百四十息，气再周于身，水下四刻，日行四十多分。二千七百息，气行十周于身，水下二十刻，日行五宿二百多分。一万三千五百息，气行五十营于身，水下百刻，日行二十八宿，漏水皆尽，脉气终了。（王冰说：这是简略的说法，详细来说，则是常以一十周加一分又十分之六，才是奇分的尽头）。所谓交通，是并行于同一数度。所以五十营具备，就能尽得天地之气，称为五十营，五脏都受气。（这段旧时在经脉根结篇末，现在移到这里。）
问：卫气的运行，出入交会的情况怎样？答：一年有十二月，一日有十二时辰，子午为经线，卯酉为纬线；天的一面有七宿，周天四七二十八宿，房宿和昴宿为纬，张宿和虚宿为经；所以从房宿到毕宿为阳，从昴宿到心宿为阴。阳主昼，阴主夜；所以卫气运行，一天一夜在周身运行五十周。白天合于阳二十五周，夜间行于阴也是二十五周，周行于五脏（另一版本作“岁”）；所以平旦时阴气尽，阳气出于目，眼睛睁开则气行于头，循行于项，下行足太阳膀胱经，循背下行至小指端。其散行者，分散于目，别行于目锐眦（一说别于目锐眦），下手太阳小肠经，下行至手小指外侧。其散行者，别行于目锐眦，下行足少阳胆经，注入小指和第二指之间。以上循行手少阳三焦经的分侧，下行至小指和第二指之间。别行者上行至耳前，合于颔脉，注入足阳明胃经，下行至足背。入足五指之间。其散行者从耳，下手阳明大肠经入大指之间。入掌中，直至于足，入足心，出内踝下行阴分，复合于目，所以为一周。所以日行一舍，人气行于身一周与十分身之八；日行二舍，人气行于身三周与十分身之六；日行三舍，人气行于身五周与十分身之四；日行四舍，人气行于身七周与十分身之二；日行五舍，人气行于身九周；日行六舍，人气行于身十周与十分身之八；日行七舍，人气行于身十二周与十分身之六；日行十四舍，人气二十五周于身有奇分与十分身之四。阳尽于阴，阴受气了。其始入于阴，常从足少阴肾经注于肾，肾注于心，心注于肺，肺注于肝，肝注于脾，脾复注于肾，为一周。所以夜行一舍，人气行于身（一说阴脏）一周与十分脏之八，也像阳的运行二十五周后复会于目。阴阳一日一夜，舍于奇分十分身之四与十分脏之四（一作二，上文十分脏之八，此言十分脏之四，疑有误）。所以人之所以卧起的时间有早晚不同，是因为奇分不尽的缘故。
问：卫气在体内，上下往来不停，诊察气而针刺它该怎么办？答：穴位深浅多少不同，日子长短不同，春夏秋冬各有分理，然后常以平旦为纪，夜尽为始。所以一天一夜，漏水一百刻。二十五刻，是半日的度数。常像这样不停止，日落而止，随着日子的长短，各自作为纪限。谨慎地等候气所在的部位而刺之。这叫逢时。病在阳分，必须先候其气加在于阳分时而刺之；病在阴分，必须先候其气加在于阴分时而刺之，谨慎地等候其时机，病可以预期治愈；失去时机反而违背规律，百病不能去除。
水下第一刻，人气在太阳经；水下第二刻，人气在少阳经；
水下第三刻，人气在阳明经；水下第四刻，人气在阴分；
水下第五刻，人气在太阳经；水下第六刻，人气在少阳经；
水下第七刻，人气在阳明经；水下第八刻，人气在阴分；
水下第九刻，人气在太阳经；水下第十刻，人气在少阳经；
水下第十一刻，人气在阳明经；水下第十二刻，人气在阴分；
水下第十三刻，人气在太阳经；水下第十四刻，人气在少阳经；
水下第十五刻，人气在阳明经；水下第十六刻，人气在阴分；
水下第十七刻，人气在太阳经；水下第十八刻，人气在少阳经；
水下第十九刻，人气在阳明经；水下第二十刻，人气在阴分；
水下第二十一刻，人气在太阳经；水下第二十二刻，人气在少阳经；
水下第二十三刻，人气在阳明经；水下第二十四刻，人气在阴分；
水下第二十五刻，人气在太阳经。这是少半日的度数。
从房宿到毕宿十四度，水下五十刻，是半日的度数。从昴宿到心宿也是十四度，水下五十刻，是一整日的度数。日行一舍，水下三刻与十分之四刻（《素问》作七刻）。大要常以日加之于宿上也，则知人气在太阳经。所以日行一宿，人气在三阳经与阴分。常像这样不停止，与天地同纪，纷纷扰扰，终而复始。一天一夜，水行百刻而尽。所以说刺实证要刺其气来之时，刺虚证要刺其气去之时，这是说气的存亡之时，以候虚实而刺之。
The human body has four seas, and the twelve Jing Rivers (twelve major meridians within the body) all flow into these seas. There is the Sea of Marrow, the Sea of Blood, the Sea of Qi, and the Sea of Water and Grain. The Stomach is the Sea of Water and Grain; its upper point is at Qichuan (Qichong, ST30), and its lower point extends to Zusanli (ST36). The Chong Mai (Penetrating Vessel) is the Sea of the Twelve Meridians; its upper point is at Dazhu (BL11), and it emerges below Shangjuxu (ST37) and Xiajuxu (ST39). Danzhong (CV17) is the Sea of Qi; its upper aspect is above and below the vertebral column, and anteriorly at Renying (ST9). The Brain is the Sea of Marrow; its upper aspect is at the crown of the head, and its lower aspect is at Fengfu (GV16). Regarding these four seas: if one follows their natural course, life is sustained; if one opposes them, decline occurs; if one knows how to regulate them, there is benefit; if one does not, there is harm. It is asked: What are the patterns of compliance and opposition in the four seas? It is answered: If the Sea of Qi is in excess, there is fullness in the chest, rapid breathing, and redness of the face; if deficient, there is shortness of breath and inability to speak. If the Sea of Blood is in excess, one constantly feels the body is large and depressed, yet does not know where the illness lies; if deficient, one constantly feels the body is small and narrow, yet does not know where the illness lies. If the Sea of Water and Grain is in excess, there is abdominal distension and fullness; if deficient, there is hunger but an inability to eat food. If the Sea of Marrow is in excess, one feels light, vigorous, and strong, exceeding normal limits; if deficient, there is dizziness, tinnitus, soreness of the shins, vertigo, blurred vision, lassitude, and a desire to lie down. It is asked: How should they be regulated? It is answered: Carefully observe their locations and regulate their deficiency and excess without causing harm; those who follow the natural order recover, while those who oppose it will fail.
Yellow Emperor asked: What is meant by Fifty Circulations? Qibo replied: The celestial sphere consists of twenty-eight mansions, each divided into thirty-six parts. The vital energy completes one circulation over 1,080 parts. The human meridians, running up, down, left, right, front, and back, number twenty-eight, with a total length of sixteen zhang and two chi, corresponding to the twenty-eight mansions. The clepsydra (water clock) drops one hundred ke (keeps), dividing day and night. Thus, with each exhalation, the pulse beats twice, and Qi moves three cun; with each inhalation, the pulse beats twice, and Qi moves three cun. Between breaths, Qi moves six cun. In ten breaths, the pulse travels six chi, and the sun moves two fen. In 270 breaths, Qi travels sixteen zhang and two chi, circulating through the interior, completing one circuit around the body, the water clock drops two ke, and the sun moves more than twenty fen. In 540 breaths, Qi circulates twice around the body, the water clock drops four ke, and the sun moves more than forty fen. In 2,700 breaths, Qi circulates ten times around the body, the water clock drops twenty ke, and the sun moves five mansions and more than two hundred fen. In 13,500 breaths, Qi performs fifty circulations around the body, the water clock drops one hundred ke, the sun completes twenty-eight mansions, the water runs out, and the meridian Qi ends. (Wang Bing said: This is a brief statement. In detail, it is usually ten circuits plus one part and six-tenths of a part, which constitutes the remainder.) What is called "traffic" refers to moving together in the same numerical measure. Therefore, when the fifty circulations are complete, one can fully embody the Qi of Heaven and Earth. This is called Fifty Circulations, as the Five Zang Organs all receive Qi. (This paragraph was originally at the end of the Root and Terminal Meridians section and has been moved here.)
It is asked: How does the Wei Qi (Defensive Qi) move, and what are its entry and exit intersections? It is answered: There are twelve months in a year and twelve double-hours in a day. Zi and Wu form the meridian lines, and Mao and You form the parallel lines. One side of the heaven has seven mansions, totaling twenty-eight mansions around the celestial sphere. Fang and Mao are parallels, Zhang and Xu are meridians. Therefore, from Fang to Bi is Yang, and from Mao to Xin is Yin. Yang governs the day, and Yin governs the night. Thus, Wei Qi circulates fifty times around the body in one day and night. During the day, it combines with Yang for twenty-five circuits, and at night, it travels through Yin for twenty-five circuits, circling the Five Zang Organs (one version reads "year"); thus, at dawn, Yin Qi is exhausted, and Yang Qi emerges from the eyes. When the eyes open, Qi travels to the head, follows the neck, descends along the Foot-Taiyang Bladder Meridian, follows the back, and reaches the tip of the little toe. Its scattered branches disperse from the eyes, branch off at the outer canthus (or another version says branch off at the outer canthus), descend along the Hand-Taiyang Small Intestine Meridian, and reach the outer side of the hand little toe. Its scattered branches branch off at the outer canthus, descend along the Foot-Shaoyang Gallbladder Meridian, and enter between the little toe and the second toe. Following this path along the lateral side of the Hand-Shaoyang Sanjiao Meridian, it descends to the space between the little toe and the second toe. Another branch ascends to the front of the ear, merges with the mandibular pulse, enters the Foot-Yangming Stomach Meridian, descends to the dorsum of the foot, and enters the spaces between the five toes. Its scattered branches go from the ear, descend along the Hand-Yangming Large Intestine Meridian, enter the space between the thumb and index finger, enter the palm, go straight to the foot, enter the sole of the foot, emerge from the medial malleolus, descend through the Yin aspects, and merge again at the eyes, thus completing one circuit. Therefore, when the sun moves through one mansion, the vital energy circulates once around the body plus eight-tenths of a circuit; when the sun moves through two mansions, it circulates three times plus six-tenths; when the sun moves through three mansions, it circulates five times plus four-tenths; when the sun moves through four mansions, it circulates seven times plus two-tenths; when the sun moves through five mansions, it circulates nine times; when the sun moves through six mansions, it circulates ten times plus eight-tenths; when the sun moves through seven mansions, it circulates twelve times plus six-tenths; when the sun moves through fourteen mansions, it circulates twenty-five times with a remainder of four-tenths. When Yang is exhausted in Yin, Yin receives the Qi. Initially entering Yin, it usually flows from the Foot-Shaoyin Kidney Meridian into the Kidneys, from the Kidneys into the Heart, from the Heart into the Lungs, from the Lungs into the Liver, from the Liver into the Spleen, and from the Spleen back into the Kidneys, completing one circuit. Thus, when the night progresses through one mansion, the vital energy circulates once around the body (or one version says Yin Zang Organs) plus eight-tenths of a circuit around the Zang Organs, just as in the Yang phase, completing twenty-five circuits before meeting again at the eyes. Yin and Yang, in one day and night, rest in the remainders of four-tenths of the body's circuits and four-tenths of the Zang Organs' circuits (one version says two; the previous text mentions eight-tenths of the Zang Organs, while this mentions four-tenths, suggesting an error). Hence, the variation in the timing of people's rising and sleeping is due to these incomplete remainders.
It is asked: Since Wei Qi moves endlessly up and down in the body, how should one palpate the Qi and apply acupuncture? It is answered: The depth and number of acupoints vary, and the length of days varies. Spring, Autumn, Winter, and Summer each have their own principles. Generally, use dawn as the standard and the end of the night as the beginning. Thus, in one day and night, the water clock drops one hundred ke. Twenty-five ke represents half a day. This continues indefinitely until sunset, adjusting according to the length of the day as the standard. Carefully await the location of the Qi and puncture it. This is called "meeting the time." If the disease is in the Yang aspects, one must first await the Qi adding to the Yang aspects before puncturing; if the disease is in the Yin aspects, one must first await the Qi adding to the Yin aspects before puncturing. Carefully awaiting the time allows the disease to be expected to heal; losing the time and contrary to the pattern, the hundred diseases will not be removed.
At the first ke of water drop, the vital Qi is in the Taiyang Meridian;
At the second ke, the vital Qi is in the Shaoyang Meridian;
At the third ke, the vital Qi is in the Yangming Meridian; At the fourth ke, the vital Qi is in the Yin aspects;
At the fifth ke, the vital Qi is in the Taiyang Meridian; At the sixth ke, the vital Qi is in the Shaoyang Meridian;
At the seventh ke, the vital Qi is in the Yangming Meridian; At the eighth ke, the vital Qi is in the Yin aspects;
At the ninth ke, the vital Qi is in the Taiyang Meridian; At the tenth ke, the vital Qi is in the Shaoyang Meridian;
At the eleventh ke, the vital Qi is in the Yangming Meridian; At the twelfth ke, the vital Qi is in the Yin aspects;
At the thirteenth ke, the vital Qi is in the Taiyang Meridian; At the fourteenth ke, the vital Qi is in the Shaoyang Meridian;
At the fifteenth ke, the vital Qi is in the Yangming Meridian; At the sixteenth ke, the vital Qi is in the Yin aspects;
At the seventeenth ke, the vital Qi is in the Taiyang Meridian; At the eighteenth ke, the vital Qi is in the Shaoyang Meridian;
At the nineteenth ke, the vital Qi is in the Yangming Meridian; At the twentieth ke, the vital Qi is in the Yin aspects;
At the twenty-first ke, the vital Qi is in the Taiyang Meridian; At the twenty-second ke, the vital Qi is in the Shaoyang Meridian;
At the twenty-third ke, the vital Qi is in the Yangming Meridian; At the twenty-fourth ke, the vital Qi is in the Yin aspects;
At the twenty-fifth ke, the vital Qi is in the Taiyang Meridian. This is the measure of less than half a day.
From Fang to Bi covers fourteen degrees, dropping fifty ke of water, which is the measure of half a day. From Mao to Xin also covers fourteen degrees, dropping fifty ke of water, which is the measure of a full day. When the sun moves through one mansion, the water drops three ke and four-tenths of a ke (Suwen reads seven ke). The general principle is to add the sun's position to the mansions to know that the vital Qi is in the Taiyang Meridian. Thus, when the sun moves through one mansion, the vital Qi is in the Three Yang Meridians and the Yin aspects. Continuing like this without end, aligning with the rhythms of Heaven and Earth, bustling and busy, ending and beginning again. In one day and night, the water runs one hundred ke and is exhausted. Therefore, it is said: To treat excess conditions, puncture when the Qi arrives; to treat deficiency conditions, puncture when the Qi departs. This speaks of the time of the presence or absence of Qi, to monitor deficiency and excess and apply acupuncture accordingly.