世谓女子之经血。为天癸。非也内经明言男子亦有天癸。而注内经者。又不能实指为何物。王冰旧注。知其所至之
地而于天癸。究未明言。吾尝细考经文。参证西法。旁及丹经别录。于阴阳水火血气数端。颇能分析。因详注之。又此
章元微。西洋医法所不能知。故西人于女子之经水。男子之精气。皆不能洞悉源委。
女子二七。而天癸至。
七为阳数。八为阴数。离为女。坎为男。皆阴阳互换之道。故男阳而得阴数。女阴而得阳数。女子七岁更齿。二七
而天癸至。天癸者。天一所生之癸水。乃肾中一阳之气。化而为液也。至者谓肾气化水。至于胞中也。
任脉通。太冲脉盛。月事以时下。
人身总统阴阳者只是任督两脉。任居前面属胃属心。主后天。督居背脊。属肾。主先天。二脉交会。则在胞中胞居
大肠之前。膀胱之后。乃是油膜中一个夹室。此胞之膜。上连网油。又上则归结于背脊中间是为肾中之系即命门也。督
脉贯之为先天阳。气之根源气即水也。西法于水中取气。凡人口鼻之气。着物皆化为水。而肾中。天一阳气所生之水则
为癸。水至者癸水发于肾。系之中下八网油。而至于胞中也。此是督脉所司。先天肾中之阳。交于胞中是水非血也。属
先天之气分其属后天血分者。则为冲任两脉波任丽于阳明属后天主奉心化血。阳明饮食所。化之精汁上归。于肺奉心火
之化则色赤为血既化成血。则由冲任两脉。导引而下行。以入胞宫。与天癸之水会合。所谓任脉通者。盖任脉起于胞中。
天一阳气所化之癸水。既从督脉下入胞中。则后天任脉感阳气而通畅。其丽于任脉者为太冲脉。亦得天癸之阳而所化之
阴血。更加盛满。于是阴血循冲任。亦下入胞中。与癸水会合。则为经血年月一行。是为月事。故曰月事以时下。女子
属阴。以血为主天癸之水气。亦从血化皆为赤色。其实中有水液也。督脉癸水之阳不足。则经迟经滞。冲任之阴血不足。
则经淡经枯。
男子二八。肾气盛。天癸至。
男女虽有不同。而其先天皆主肾。后天皆主胃。男子二八。先天肾中生阳之气。所化癸。水亦至胞中。女子之胞名
血海。名子宫。以其行经孕子也。男子之胞名丹田。名气海。名精室。以其为呼吸之根藏精之所也。胞乃先后天。交会
之所先天督脉肾阳。所化之水既至胞中则后天冲任。奉心所化之血。与水相应而冲任通畅亦下胞中为阴。与阳应气与血
交女子以血为主。则水从血化而为经男子以气。为主则血从水化而为精。精清者血不足。精不射者气不足。精少者。气
血均不足。
精气溢泻。
血从水气之化。而非清水。必稠浊者。以其水中有血质。故也惟其血与水合化。而后精气溢满。得泻出矣。西医言
精是外肾睾丸所生不知睾丸只是发精之器。非生精之所。西医因剖视。只见睾丸内有精。而别处无精。不知精生则营运
不见。既死之人。而求其化生所在决不得矣。睾丸中之精亦死精耳。安可据此以为生精处哉。详全体总论篇。
阴阳和。故有子。
此又统男女言之。天癸水为阳。冲任之血。为阴和者。谓会于胞中。协议而化也女和则经行。男和则精溢。故能生
育而有子。今人不知此理。而妄行服药。以求有子。能无误乎。
此节乃血气交会。化为。月信变为肾精。之原委最要之义也。化为精者。上行循督脉而入脊。上脑是生骨髓。循任
脉而上。颊绕唇。是生髭须出。于皮肤生毛亦较女子更重。盖男子之血不下。泻化精气而上行。外达所以多须毛也。血
主阴主下行。女子之水从血化而为经则内行下达每月一泻其余血气既下泻所以上无髭须。外少毛毫也。且女子之骨较弱。
亦以经血下行。而上生骨髓者少矣。西医论髓而不知髓是何物。所生只原未识气血变化之理也。另详于后。
世人认为女子的经血就是天癸，这是不对的。《内经》明确说明男子也有天癸，而注释《内经》的人，又不能确切指出天癸究竟是什么东西。王冰在旧注中，只知道天癸到达的地方，但对于天癸本身，终究没有明确说明。我曾经仔细考证经文，参考西医方法，并旁涉丹经和其他记录，对于阴阳、水火、血气等几个方面，颇能进行分析，因此详细加以注释。另外，这一章的内容原本很隐微，是西洋医学法所不能知晓的，所以西方人对于女子的经水、男子的精气，都不能透彻了解其来源和委曲。
女子到了十四岁（二七），天癸就来了。
七是阳数，八是阴数。离卦代表女，坎卦代表男，这都是阴阳互换的道理。所以男子属阳却得到阴数（八），女子属阴却得到阳数（七）。女子七岁时换牙，到了十四岁天癸就到了。所谓天癸，是天一所生的癸水，是肾中的一阳之气，化生为液体。“至”的意思是肾气化生水，到达胞宫（子宫）中。
任脉通畅，太冲脉旺盛，月经按时来潮。
人体统管阴阳的只是任脉和督脉这两条经脉。任脉位于前面，属于胃、属于心，主管后天；督脉位于背部脊柱，属于肾，主管先天。这两条经脉交会的地方，就在胞宫中。胞宫位于大肠之前，膀胱之后，是在油膜（腹膜/脂肪组织）中的一个夹室。这个胞宫的膜，向上连接网油，再向上归结于背脊中间，这就是肾中的系带，也就是命门。督脉贯穿其中，作为先天的阳气，气的根源就是水。西医认为在水中可以取得气，凡是人口鼻呼吸之气，接触物体都会化为水，而肾中由天一阳气所生的水则称为癸。水到达时，癸水发源于肾，经过系带下方的八层网油，到达胞宫中。这是督脉所主管的，是先天的肾中之阳，交会在胞宫中，这是水而不是血。属于先天气分的，与属于后天气分对应的，则是冲脉和任脉。任脉依附于阳明经（胃经），属于后天，主管奉受心火化生的血液。阳明经饮食所化的精汁，向上归并于肺，奉受心火的化育，颜色变红成为血。既然已经化成血，就由冲脉和任脉引导下行，进入胞宫，与天癸之水会合。所谓“任脉通”，大概是因为任脉起于胞中，天一阳气所化的癸水，已经从督脉下入胞中，那么后天的任脉感应到阳气而通畅。依附于任脉的是太冲脉，也得到天癸的阳气，而它所化的阴血，更加盛满。于是阴血循着冲脉和任脉，也下入胞中，与癸水会合，就成为经血，每月一次，这叫做月事。所以说“月事以时下”。女子属阴，以血为主，天癸的水气，也从血化生，都是赤色的，其实里面含有水液。如果督脉癸水的阳气不足，就会导致月经推迟、经行不畅；如果冲任的阴血不足，就会导致经血色淡、经血枯竭。
男子到了十六岁（二八），肾气旺盛，天癸就到了。
男女虽然有所不同，但他们的先天都主司于肾，后天都主司于胃。男子到了十六岁，先天肾中生发的阳气，所化的癸水，也到达胞中。女子的胞宫名叫血海，名叫子宫，因为它行经、孕育胎儿。男子的胞宫名叫丹田，名叫气海，名叫精室，因为它是呼吸的根本、藏精的场所。胞宫是先后天交会的地方。先天的督脉肾阳所化的水既已到达胞中，那么后天的冲脉和任脉，奉受心所化的血，与水相应，而冲脉和任脉通畅，也下入胞中，使阴与阳相应，气与血相交。女子以血为主，所以水从血化而为经血；男子以气为主，所以血从水化而为精。精液清稀是因为血不足，射精无力是因为气不足，精液量少是因为气血均不足。
精气满溢而泻出。
血是从水气化生而来的，并不是清水，一定是稠浊的，这是因为水中含有血质的缘故。只有血与水合化，然后精气才满溢，得以泻出。西医说精液是由外肾（睾丸）产生的，不知道睾丸只是发射精液的器官，不是产生精液的场所。西医因为解剖观察，只见睾丸内有精液，而别处没有精液，却不知道精液生成时运行变化是不可见的。对于已经死亡的人，去寻找其化生的所在，是绝对找不到的。睾丸中的精液也是死精罢了，怎么可以根据这个就认为是产生精液的场所呢？详见《全体总论篇》。
阴阳调和，所以能有子女。
这又是统括男女来说的。天癸之水为阳，冲任之血为阴。“和”的意思是指它们在胞中会合，协议而化育。女子调和则经血通行，男子调和则精液满溢，所以能生育而有子女。现在的人不知道这个道理，而胡乱服药，以求得子，能不犯错吗？
这一节讲的是血气交会，化为月信（月经），进而变为肾精的原委，是最重要的义理。化为精者，上行循督脉进入脊柱，上达脑部，这是生成骨髓的过程；循任脉而上，环绕脸颊嘴唇，这是生成胡须的过程，长出皮肤上的毛发也比女子更浓重。大概是因为男子的血不下泄，而是化为精气上行，外达体表，所以胡须毛发多。血主阴、主下行，女子的水从血化而为经血，则内行下达，每月一泻，其余的血气既然向下泻泄，所以上面没有胡须，外面少有毫毛。而且女子的骨骼较弱，也是因为经血下行，而上行生成骨髓的就少了。西医论述骨髓，却不知道骨髓是什么东西，所探究的只是本源，未识气血变化的道理。另在后面详细说明。
It is commonly said that the menstrual blood of women is Tian Gui (Heavenly Water / Reproductive Essence), which is incorrect. The *Neijing* (Inner Canon) explicitly states that men also possess Tian Gui, yet commentators on the *Neijing* fail to precisely identify what this substance actually is. Wang Bing’s old commentary knows the destination where it arrives but ultimately fails to clearly define Tian Gui itself. I have carefully examined the canonical texts, cross-referenced with Western medical methods, and consulted alchemical treatises and other records. Regarding the aspects of Yin-Yang, Water-Fire, Blood, and Qi, I am able to provide a detailed analysis, hence these detailed annotations. Furthermore, the subtlety of this chapter is beyond the comprehension of Western medicine; thus, Western practitioners cannot thoroughly understand the origins and complexities of menstrual water in women or essence-semen in men.
When a girl reaches fourteen years of age (two times seven), Tian Gui arrives.
Seven is a Yang number, and eight is a Yin number. The Li trigram represents woman, and the Kan trigram represents man; both illustrate the principle of mutual transformation between Yin and Yang. Therefore, although men are Yang, they correspond to the Yin number (eight); although women are Yin, they correspond to the Yang number (seven). At seven years old, girls change their teeth; at fourteen, Tian Gui arrives. "Tian Gui" refers to the Gui Water generated by Heaven One. It is the Yang Qi within the Kidney that transforms into fluid. "Arrives" means that the Qi transformation of the Kidney generates water, which reaches the Bao Gong (Uterus).
The Ren Mai (Conception Vessel) becomes unobstructed, and the Chong Mai (Penetrating Vessel) becomes abundant, causing menstruation to occur at regular intervals.
The two meridians that govern Yin and Yang throughout the body are the Ren Mai and the Du Mai (Governor Vessel). The Ren Mai is located anteriorly, associated with the Stomach and Heart, and governs Post-Heaven existence. The Du Mai is located along the dorsal spine, associated with the Kidneys, and governs Pre-Heaven existence. These two meridians intersect within the Bao Gong. The Bao Gong is situated anterior to the Large Intestine and posterior to the Bladder, functioning as a chamber within the fatty membranes (peritoneum/adipose tissue). The membrane of this Bao Gong connects upward to the omental fat and further up to the center of the dorsal spine; this is the connection within the Kidneys, known as the Ming Men (Gate of Life). The Du Mai penetrates through it, serving as the root of Pre-Heaven Yang Qi. Since Qi is essentially Water, Western medicine posits that Qi can be extracted from water; all air exhaled from the mouth and nose condenses into water upon contact with objects. However, the water generated by the Yang Qi of Heaven One within the Kidneys is specifically termed Gui Water. When this water arrives, Gui Water originates from the Kidneys, passes through the eight layers of omental fat below the connecting tissues, and reaches the Bao Gong. This is governed by the Du Mai, representing the Pre-Heaven Yang Qi of the Kidneys interacting within the Bao Gong. This interaction involves Water, not Blood. That which belongs to the Pre-Heaven Qi aspect corresponds to the Chong and Ren vessels belonging to the Post-Heaven Blood aspect. The Ren Mai adheres to the Yangming Meridian (Stomach Meridian), governing Post-Heaven functions, and receives blood transformed by the Heart Fire. The refined essences from dietary intake processed by the Yangming Meridian ascend to the Lungs, undergo transformation via Heart Fire, turn red, and become Blood. Once formed, this Blood is guided downward by the Chong and Ren vessels into the Bao Gong, where it combines with the Tian Gui Water. The phrase "Ren Mai becomes unobstructed" implies that since the Gui Water, transformed by the Yang Qi of Heaven One, has descended into the Bao Gong via the Du Mai, the Post-Heaven Ren Mai responds to this Yang Qi and becomes patent. The Tai Chong Mai, which adheres to the Ren Mai, also receives the Yang Qi of Tian Gui, causing its transformed Yin Blood to become even more abundant. Consequently, this Yin Blood follows the Chong and Ren vessels, descending into the Bao Gong to combine with the Gui Water, thereby forming menstrual blood. Occurring once a month, this is called "Yue Shi" (Monthly Affairs). Hence, it is said that "menstruation occurs at regular intervals." Women belong to Yin and prioritize Blood. The Qi of Tian Gui Water also transforms from Blood, appearing reddish, though it inherently contains fluid. If the Yang Qi of the Du Mai's Gui Water is insufficient, menstruation will be delayed or stagnant. If the Yin Blood of the Chong and Ren vessels is insufficient, menstruation will be pale or scanty.
When a boy reaches sixteen years of age (two times eight), Kidney Qi becomes robust, and Tian Gui arrives.
Although men and women differ, their Pre-Heaven nature is primarily governed by the Kidneys, and their Post-Heaven nature by the Stomach. At sixteen, the Yang Qi generated within the Kidneys of the Pre-Heaven stage produces Gui Water, which also reaches the Bao Gong. The Bao Gong in women is called the Sea of Blood or Uterus because it menstruates and bears children. The Bao Gong in men is called the Dantian, Sea of Qi, or Chamber of Essence because it is the root of respiration and the repository for storing Essence. The Bao Gong is the intersection of Pre-Heaven and Post-Heaven. When the water transformed by the Pre-Heaven Du Mai Kidney Yang arrives in the Bao Gong, the Post-Heaven Chong and Ren vessels, receiving the blood transformed by the Heart, respond to this water. The Chong and Ren vessels become unobstructed, descending into the Bao Gong, allowing Yin to correspond with Yang and Qi to interact with Blood. Women prioritize Blood, so Water transforms from Blood into menstruation. Men prioritize Qi, so Blood transforms from Water into Essence. Clear semen indicates Blood deficiency; weak ejaculation indicates Qi deficiency; low semen volume indicates both Qi and Blood deficiencies.
Essence and Qi overflow and are emitted.
Blood is transformed from Water Qi and is not clear water; it must be thick and turbid because it contains blood substances. Only when Blood and Water combine and transform does Essence and Qi become full enough to be emitted. Western medicine claims that semen is produced by the external kidneys (testicles), failing to realize that the testicles are merely organs for emitting semen, not producing it. Due to anatomical dissection, Westerners see only semen within the testicles and none elsewhere, unaware that the generation and circulation of semen are invisible processes. In a deceased person, one cannot locate the site of its generation. The semen found in the testicles is dead semen; how can this serve as proof of the production site? See the "General Discussion on the Whole Body" chapter for details.
When Yin and Yang harmonize, offspring are conceived.
This statement applies generally to both men and women. Tian Gui Water is Yang, and the Blood of the Chong and Ren vessels is Yin. "Harmonize" means they meet in the Bao Gong and collaborate to generate life. In women, harmony results in the flow of menstruation; in men, harmony results in the emission of semen. Thus, reproduction and conception are possible. Today, people ignore this principle and recklessly take medications seeking offspring, leading to errors.
This section explains the origin and process of Blood and Qi intersecting to form menstruation, which subsequently transforms into Kidney Essence. This is the most crucial principle. When transformed into Essence, it ascends along the Du Mai into the spine and up to the brain, generating Marrow. Ascending along the Ren Mai, it circles the cheeks and lips, generating facial hair, and emerges in the skin as body hair, which is denser than in women. This is because men do not shed blood downward but instead transform it into Essence and Qi that ascends and reaches the exterior, resulting in abundant hair and beard. Blood is Yin and tends to descend. Women’s water transforms from Blood into menstruation, flowing inward and downward, shedding monthly. Since the remaining Blood and Qi are directed downward, there is no facial hair above and little body hair externally. Moreover, women’s bones are weaker because less Blood ascends to generate Marrow due to the downward flow of menstruation. Western discussions on Marrow fail to identify what Marrow truly is, focusing only on origins while ignoring the principles of Blood and Qi transformation. This is detailed separately later.