（素问上古天真论 附∶种子说）
帝曰∶人年老而无子者，材力尽邪？将天数然也？（材力，精力也。天数，天赋之限数也。）岐伯曰∶女子七岁肾气
盛，齿更发长。（七为少阳之数，女本阴体而得阳数者，阴中有阳也。人之初生，先从肾始，女至七岁，肾气稍盛。肾主
骨，齿者骨之余，故齿更。肾为精血之脏，发者血之余，故发长。愚按∶男子属阳，当合阳数，女子属阴，当合阴数；
而今女反合七，男反合八何也？盖天地万物之道，惟阴阳二气而已，阴阳作合，原不相离，所以阳中必有阴，阴中必有
阳，儒家谓之互根，道家谓之颠倒，皆所以发明此理也。如离火属阳居南，而其中则偶，是外阳而内阴也；坎水属阴居
北，而其中则奇，是外阴而内阳也。震坎艮是为三男，而阴多于阳；巽离兑是为三女，而阳多于阴。悟真篇曰；日居离
位反为女，坎配蟾宫却是男。是皆阴阳颠倒之义。故女子外为阴体而内合阳数，男子外为阳体而内合阴数。如左传昭公
元年医和云，女阳物而晦时，乃亦以女为阳矣，此皆医家当察也。更，平声。长，上声。下同。）二七而天癸至，任脉通，
太冲脉盛，月事以时下，故有子。（天癸者，天一之气也。任冲者，奇经之二也，任主胎胞，冲为血海，气盛脉通，故月
事下而有子。月事者，言女子经水按月而至，其盈虚消长应于月象。经以应月者，阴之所生也。愚按∶天癸之义，诸家
俱即以精血为解；然详玩本篇谓女子二七天癸至，月事以时下，男子二八天癸至，精气溢泻，是皆天癸在先，而后精血
继之，分明先至后至，各有其义，焉得谓天癸即精血，精血即天癸？本末混淆，殊失之矣。夫癸者，天之水，干名也。
干者支之阳，阳所以言气；癸者壬之偶，偶所以言阴。故天癸者，言天一之阴气耳，气化为水，因名天癸，此先圣命名
之精而诸贤所未察者。其在人身，是为元阴，亦曰元气。人之未生，则此气蕴于父母。是为先天之元气；人之既生，则
此气化于吾身，是为后天之元气。第气之初生，真阴甚微，及其既盛，精血乃王，故女必二七、男必二八而后天癸至。
天癸既至，在女子则月事以时下，在男子则精气溢泻，盖必阴气足而后精血化耳。阴气阴精，譬之云雨，云者阴精之气
也，雨者阴气之精也，未有云雾不布而雨雪至者，亦未有云雾不浓而雨雪足者。然则精生于气，而天癸者，其即天一之
气乎，可无疑矣。列子曰∶有生者，有生生者；有形者，有形形者。其斯之谓。）三七肾气平均，故真牙生而长极。（肾
气，即天癸也。平均，充满之谓。真牙，谓牙之最后生者。肾主骨，故肾气平则真牙生而长极。）四七筋骨坚，发长极，
身体盛壮。（女子天癸之数，七七而止，年当四七，正及材力之中，故身体盛壮，发长极矣。）五七阳明脉衰，面始焦，
发始堕。（女为阴体，不足于阳，故其衰也，自阳明始。阳明之脉行于面，循发际，故面焦发堕。）六七三阳脉衰于上，
面皆焦，发始白。（三阳脉皆盛于面也。）七七任脉虚，太冲脉衰少，天癸竭，地道不通，故形坏而无子也。（至是则冲任
血少，阴气竭，故经水止绝而坤道不通也。天癸竭绝，故形体衰坏而不能有子矣。）丈夫八岁肾气实，发长齿更。（八为
少阴之数，男本阳体而得阴数者，阳中有阴也。发长齿更义同前。）二八肾气盛，天癸至，精气溢泻，阴阳和，故能有子。
（男女真阴，皆称天癸，天癸既充，精乃溢泻，阴阳和合，故能生子。子者统男女而言，男曰男子，女曰女子。愚按∶
有子之道，必阴阳合而后胎孕成，故天一生水而成于地之六，地二生火而成于天之七，所以万物之生，未有不因阴阳相
感而能成其形者，此一阴一阳之谓道也。至于成男成女之说，按北齐褚澄曰∶男女之合，二精交畅，阴血先至，阳精后
冲，血开裹精，精入为骨，而男形成矣；阳精先入，女血后参，精开裹血，血入为本，而女形成矣。启玄子曰∶男女有
阴阳之质不同，天癸则精血之形亦异。故自后医家皆宗其说，而近者玄台马氏驳之曰∶男女之精，皆可以天癸称；今王
注以女子之天癸为血，则男子之天癸亦为血耶？易曰∶男女构精，万物化生。故交构之时，各有其精，而行经之时，方
有其血。未闻交构之时，可以血言。广嗣诸书，皆言精裹血、血裹精者亦非。此马氏之说诚是也。又按李东垣曰∶经水
断后一二日，血海始净，精胜其血，感者成男；四五日后血脉已王，精不胜血，感者成女。朱丹溪曰∶夫乾坤，阴阳之
情性也；左右，阴阳之道路也；男女，阴阳之仪象也。阴阳交构，胎孕乃凝，所藏之处，名曰子宫，一系在下，上有两
岐，中分为二，形如合钵，一达于左、一达于右。精胜其血，则阳为之主，受气于左子宫而男形成；精不胜血，则阴为
之主，受气于右子宫而女形成。若此诸说不同，未必皆为确论；然以愚见，亦有谓焉。如王氏以精血为天癸，盖以经文
言女子之血，男子之精，皆随天癸而至故也。此虽未得其真，而其义犹不相远。至于褚氏之说，则必所不然。盖男女相
合，两精和畅，本无血至之事。惟是结胎之后，男以精而肇其元，女以血而成其体，此以男精女血而谓之构，自是正理。
若以交会之际，而言其精裹血、血裹精者，诚然谬矣。此不若丹家以阳精为天壬、阴精为地癸者为妥。其说曰∶天壬先
至，地癸随至，癸裹壬则成男子；地癸先至，天壬随至，壬裹癸则成女子；壬癸齐至，则成双胎；一迟一速，俱不成胎。
天壬地癸者，乃天地元精元气也。虽然，此固一说也，但亦涉于渺茫耳。若东垣之说，则以数日之后，感必成女。第以
近验，求男者每用三十时辰、两日半之法，而有必不免于女者，有在二十日以外而得男者，此皆与东垣相反矣。若丹溪
以左右者阴阳之道路一句为论，乃指既受之后为言，而亦未明其所以然。且左右者，言阴阳升降之理，岂此两岐之谓，
尤属太奇。若必欲得其实理，则干道成男，坤道成女，阳胜阴者为男，阴胜阳者为女，此为不易之至论。然阴阳盛衰之
说固如此，而亦何以见其详？如老阳少阴，强弱判矣；羸阳壮阴，盛衰分矣。壮而不蓄，同乎弱矣；老而知养，同于少
矣。期候有阴阳，忽之者其气衰；起居有消长，得之者其气盛。两军相对，气可夺于先声；一静自持，机待时而后动。
以寡击众，孰谓无方？转弱为强，果由妙用。受与不受在阖辟，不在浅深，言迟疾者殊谬；男与不男在盈虚，不在冲裹，
道先后者尤差。凡寡欲而得之男女贵而寿，多欲而得之男女浊而夭，何莫非乾坤之道乎？！知之者，岂惟擅璋瓦之权，
而蓝田久无烟焰者，不外此也；子女生而夭弱者，不外此也。有子女之念者，其留意于是焉。）三八肾气平均，筋骨劲强，
故真牙生而长极。（肾水生肝血，故筋亦劲强也。余注同前女子。）四八筋骨隆盛，肌肉满壮。（男子气数至此，盛之极也。）
五八肾气衰，发堕齿槁。（男为阳体，不足于阴，故其衰也自肾始，而发齿其征也。）六八阳气衰竭于上，面焦，发鬓颁
白。（阳气，亦三阳气也。颁，班同。）七八肝气衰，筋不能动，天癸竭，精少，肾脏衰，形体皆极。（肝主筋，肝衰故筋
不能动。肾主骨，肾衰故形体疲极。）八八则齿发去。（衰之甚也。）肾者主水，受五脏六腑之精而藏之，故五脏盛乃能泻。
（肾为水脏，精即水也，五脏六腑之精，皆藏于肾，非肾脏独有精也，故五脏盛则肾乃能泻。）今五脏皆衰，筋骨解堕，
天癸尽矣。故发鬓白，身体重，行步不正，而无子耳。（凡物壮则老，此上文所谓天数也。解，懈同。）帝曰∶有其年已
老而有子者何也？岐伯曰∶此其天寿过度，气脉常通，而肾气有余也。（此天禀有余，即所谓材力也。）此虽有子，男不
过尽八八，女不过尽七七，而天地之精气皆竭矣。（天癸大数，女已尽于七七，男已尽于八八，精气既竭，此外多难于子
矣。）帝曰∶夫道者年皆百数，能有子乎？岐伯曰∶夫道者能却老而全角，身年虽寿，能生子也。道者，言合道之人也。
既能道合天地，则其材力天数，自是非常，却老全角，寿而生子，固有出人之表，而不可以常数限者矣。此篇大意，帝
以材力天数为问，而岐伯之答，如天癸盛衰者，言材力也；七七八八者，言天数也。虽材力之强者，若出于数限之外，
而其所以能出者，又何莫非天禀之数乎？其有积精全神，而能以人力胜天者，惟法则天地而协议于道者，为能及之也。）
《素问·上古天真论》附：种子说
黄帝问道：人到了年老而不能生育子女，是因为精力耗尽了呢？还是因为天赋的自然寿命限制呢？（“材力”指人的精力；“天数”指天赋的寿命极限。）
岐伯回答说：女子七岁时，肾气开始旺盛，牙齿更换，头发生长。（“七”是少阳之数。女子本属阴体，却得到阳数，说明阴中有阳。人刚出生时，先从肾脏发育开始，女子到七岁，肾气稍微旺盛。肾主骨，牙齿是骨的余绪，所以牙齿更换。肾是精血之脏，头发是血的余绪，所以头发生长。我按语道：男子属阳，应当符合阳数；女子属阴，应当符合阴数。但为什么女子反而符合七，男子反而符合八呢？大概天地万物的道理，只有阴阳二气罢了，阴阳结合，原本不可分离，所以阳中必有阴，阴中必有阳。儒家称之为互根，道家称之为颠倒，都是用来阐明这个道理的。比如离火属阳位居南方，但其中是偶爻，这是外阳而内阴；坎水属阴位居北方，但其中是奇爻，这是外阴而内阳。震、坎、艮是三男卦，阴多于阳；巽、离、兑是三女卦，阳多于阴。《悟真篇》说：“日居离位反为女，坎配蟾宫却是男。”这都是阴阳颠倒的含义。所以女子外表是阴体，但内在符合阳数；男子外表是阳体，但内在符合阴数。如《左传》昭公元年医和说，女子是阳物且在晦时（夜晚）行房，也是把女子看作阳。这些都是医生应当考察的。“更”读平声，“长”读上声，以下相同。）女子十四岁时，天癸（促进生殖功能成熟的物质）到来，任脉通畅，太冲脉旺盛，月经按时来潮，所以能够生育。（“天癸”是天一之气。“任”和“冲”是奇经中的两条，任脉主管胎胞，冲脉是血海，气盛脉通，所以月经下行并能生育。所谓月事，是说女子的经水按月而至，其盈亏消长对应月亮的圆缺。经水应合月亮，是因为它是阴所生。我按语道：关于天癸的含义，各家都解释为精血；然而仔细玩味本篇，说女子二七天癸至，月事以时下，男子二八天癸至，精气溢泻，这说明天癸先到，然后精血继之，分明是先至后到，各有含义，怎么能说天癸就是精血，精血就是天癸呢？这混淆了本末，大错特错了。那“癸”是天之水，天干之名。“干”是支之阳，阳所以言气；“癸”是壬之偶，偶所以言阴。所以天癸，说的是天一之阴气罢了，气化为水，因此名叫天癸，这是先圣命名的精妙之处，而各位贤者未曾察觉到的。它在人身，称为元阴，也称元气。人未出生时，此气蕴藏在父母体内，称为先天之元气；人出生后，此气化生于自身，称为后天之元气。只是气初生时，真阴很微弱，等到它旺盛时，精血才王（旺），所以女子必须到十四岁、男子必须到十六岁之后天癸才至。天癸既已到来，在女子则月经按时来潮，在男子则精气满溢排泄，这一定是阴气充足而后精血才能化生。阴气和阴精，好比云雨，云是阴精之气，雨是阴气之精，没有云雾不布散而雨雪降临的，也没有云雾不浓厚而雨雪充足的。既然这样，精生于气，而天癸，大概就是天一之气吧，这可以毫无疑问了。列子说：“有生者，有生生者；有形者，有形形者。”说的就是这个意思。）女子二十一岁时，肾气平和均匀，所以智齿生长，身体发育达到极点。（肾气，即天癸。平均，指充满的状态。真牙，指最后生长的牙齿。肾主骨，所以肾气平和则真牙生长且身体发育至极。）女子二十八岁时，筋骨坚固，头发长到极点，身体处于最壮盛的时期。（女子天癸的周期，到七七四十九岁结束，年龄正值四七二十八岁，正是精力充沛的中期，所以身体壮盛，头发长到极点。）女子三十五岁时，阳明脉开始衰退，面部开始憔悴，头发开始脱落。（女子属阴体，阳气不足，所以衰老从阳明脉开始。阳明脉行于面部，循行发际，所以面焦发堕。）女子四十二岁时，三阳脉在头部开始衰退，面部完全憔悴，头发开始变白。（三阳脉都旺盛于面部。）女子四十九岁时，任脉虚衰，太冲脉气血衰少，天癸枯竭，月经停止（地道不通），所以形体衰败而不能生育了。（到了这个时候，冲任血少，阴气竭尽，所以经水止绝而女性生理通道不通。天癸枯竭，所以形体衰坏而不能有子。）
男子八岁时，肾气充实，头发生长，牙齿更换。（“八”是少阴之数。男子本属阳体，却得到阴数，说明阳中有阴。头发生长、牙齿更换的道理同前文所述。）男子十六岁时，肾气旺盛，天癸到来，精气满溢排泄，阴阳调和，所以能够生育。（男女的真阴，都称为天癸，天癸充盈，精液才溢泻，阴阳和合，所以能生子。“子”统指男女而言，男称男子，女称女子。我按语道：生育的道理，必须阴阳结合而后胎孕形成，所以天一生水而成于地之六，地二生火而成于天之七，因此万物的生成，没有不因阴阳相感而能成形的，这就是一阴一阳叫做道的道理。至于成男成女的说法，据北齐褚澄说：男女交合，两精交畅，如果阴血先到，阳精后冲，血打开包裹精，精进入成为骨骼，那么男婴就形成了；如果阳精先入，女血后参，精打开包裹血，血进入成为根本，那么女婴就形成了。启玄子说：男女有阴阳体质不同，天癸表现为精血的形态也各异。所以后世医家都尊崇这种说法，而近代的玄台马氏驳斥说：男女的精，都可以称为天癸；现在王冰注解说女子的天癸是血，那么男子的天癸也是血吗？《易经》说：男女构精，万物化生。所以在交合之时，各自有其精，而在行经之时，才有其血。没听说过交合之时可以用血来说明。各种广嗣书籍，都说精裹血、血裹精，这也是不对的。马氏的说法确实正确。又据李东垣说：月经断后一二日，血海刚刚干净，精胜过了血，受孕则成男；四五日后血脉正旺盛，精不胜血，受孕则成女。朱丹溪说：乾坤是阴阳的情性，左右是阴阳的道路，男女是阴阳的仪象。阴阳交合，胎孕乃凝结，所藏之处，名叫子宫，有一条系带在下，上面有两个分支，中间分为二，形状像合钵，一个通达左边，一个通达右边。如果精胜过了血，则阳为主宰，受气于左子宫而男婴形成；如果精不胜血，则阴为主宰，受气于右子宫而女婴形成。像这些说法各不相同，未必都是确切的结论；然而依我看来，也有可说的地方。如王氏将精血视为天癸，大概是根据经文说女子的血、男子的精，都随天癸而至的缘故。这虽然未得其真谛，但其义理尚不相远。至于褚氏的说法，则必定是不对的。大概男女相合，两精和畅，本来就没有血至的事情。只是结胎之后，男以精而肇始其元气，女以血而完成其形体，这是以男精女血而称之为“构”，自然是正理。如果在交合之际，说精裹血、血裹精，确实是谬误。这不如道家以阳精为天壬、阴精为地癸的说法妥当。他们的说法是：天壬先到，地癸随后到达，癸裹壬则成男子；地癸先到，天壬随后到达，壬裹癸则成女子；壬癸同时到达，则成双胎；一迟一速，都不能成胎。天壬地癸，乃是天地的元精元气。虽然如此，这固然是其中一种说法，但也涉于渺茫。至于李东垣的说法，则是认为在经期后几天受孕必成女。但根据近期的验证，求男者每用三十时辰、两日半的方法，却仍有不免得女的，有的在二十日以外得男的，这些都与李东垣相反。至于朱丹溪以“左右者阴阳之道路”一句来论述，是指受孕之后的情况而言，也未阐明其中的原理。况且“左右”说的是阴阳升降的道理，难道是指那两个分支吗？尤其显得太奇特。如果一定要探求其实理，那么乾道成男，坤道成女，阳胜阴者为男，阴胜阳者为女，这是不可改变的至论。然而阴阳盛衰的道理固然如此，又如何能见其详细呢？比如老阳与少阴，强弱已经判然；羸弱的阳与壮盛的阴，盛衰已经区分。壮盛而不蓄积，等同于衰弱；年老而懂得调养，等同于年少。候气有阴阳之分，忽视它则气衰；起居有消长规律，顺应它则气盛。两军相对，气势可在先声中被夺取；保持静定自持，时机等待后来发动。以寡击众，谁说没有方法？转弱为强，果由妙用。受孕与否在于子宫的阖辟，不在于深浅，说快慢的是大错；生男或生女在于盈虚，不在于冲裹，说道先后更是差错。凡是寡欲而受孕的，子女高贵且长寿；多欲而受孕的，子女浑浊且短命，这哪不是乾坤之道呢！懂得这个道理的人，岂止是掌握生男生女的权柄，而且那些蓝田久无烟焰（指无子）的人，也不外乎此理；子女出生后夭折瘦弱的，也不外乎此理。有想要子女念头的人，应当留意于此。）男子二十四岁时，肾气平和均匀，筋骨强劲有力，所以智齿生长，身体发育达到极点。（肾水生肝血，所以筋也强劲有力。其余注释同前文女子部分。）男子三十二岁时，筋骨隆盛，肌肉丰满壮实。（男子的气数到此，是盛极之时。）男子四十岁时，肾气开始衰退，头发脱落，牙齿枯槁。（男子属阳体，阴气不足，所以衰老从肾开始，而头发和牙齿是其征象。）男子四十八岁时，阳气在头部衰竭，面部憔悴，鬓角头发斑白。（阳气，也是三阳之气。“颁”同“班”。）男子五十六岁时，肝气衰退，筋脉不能灵活运动，天癸枯竭，精液减少，肾脏衰退，形体极度疲乏。（肝主筋，肝衰故筋不能动。肾主骨，肾衰故形体疲极。）男子六十四岁时，牙齿头发脱落。（这是衰老严重的表现。）
肾主水，接受五脏六腑的精微并贮藏起来，所以五脏旺盛后才能向肾输送精气。（肾是水脏，精即水，五脏六腑的精，都贮藏于肾，并非肾脏独有精，所以五脏盛则肾乃能泻。）现在五脏都衰退了，筋骨松弛懈怠，天癸耗尽。所以鬓发变白，身体沉重，行走不稳，而不能生育了。（大凡事物强壮就会衰老，这就是上文所说的天数。“解”同“懈”。）
黄帝问道：有的人年纪已经老了却有子女，这是为什么呢？岐伯回答说：这是因为他的天赋寿命超过常人，气脉经常通畅，而且肾气有余。（这是天禀有余，也就是所谓的“材力”。）这种人虽然有子女，但男子不超过六十四岁（八八），女子不超过四十九岁（七七），而天地的精气都已经竭尽了。（天癸的大限，女子已在七七岁耗尽，男子已在八八岁耗尽，精气既已竭尽，此外很难再有子女了。）
黄帝问道：修道的人年龄都已近百岁，还能有子女吗？岐伯回答说：修道的人能够延缓衰老并保持身体强健，虽然实际年龄很高，但能生育子女。“道者”，指合于大道的人。既然能与天地之道相合，那么他的材力和天数，自然非常特殊，延缓衰老、保持强健，高龄生子，本来就有超出常人的表现，不能用常规的数字来限制。这篇大意，黄帝以材力和天数为问，而岐伯的回答，如天癸的盛衰，说的是材力；七七八八的岁数，说的是天数。虽然材力强盛的人，似乎超出了数字的限制，但他之所以能超出，又何尝不是天赋的数呢？那些积聚精气、保全精神，能以人力胜过天命的人，只有效法天地、协议于道的人，才能达到这种境界。）
*Suwen: Shanggu Tianzhen Lun* (Plain Questions: Discussion on the Natural Vitality of Antiquity) Appendix: Theory of Seed-Planting (Conception)
The Yellow Emperor asked: When a person becomes old and unable to have children, is it because their vital energy (*Caili*, physical vitality) has been exhausted, or is it due to the natural limit of their lifespan (*Tianshu*, heavenly mandate)?
Qibo replied: At the age of seven, a girl's *Shenqi* (Kidney Qi) begins to flourish; her teeth are replaced, and her hair grows. (Seven is the number of Shaoyang. Although the female body is fundamentally Yin, she receives the Yang number, indicating that Yin contains Yang. Human development begins with the Kidneys from birth. By age seven, a girl's Kidney Qi becomes slightly robust. The Kidneys govern bones, and teeth are the surplus of bones; hence, teeth are replaced. The Kidneys are the zang organ of essence and blood, and hair is the surplus of blood; hence, hair grows. My commentary notes: Men belong to Yang and should correspond to Yang numbers; women belong to Yin and should correspond to Yin numbers. Why do women correspond to seven and men to eight? The principle of heaven and earth and all things lies solely in the two energies of Yin and Yang. Yin and Yang combine and cannot be separated; thus, there must be Yin within Yang, and Yang within Yin. Confucianism calls this "mutual root," while Daoism calls it "inversion," both elucidating this principle. For instance, Li Fire belongs to Yang and resides in the South, but its trigram contains an even line (Yin), representing external Yang and internal Yin. Kan Water belongs to Yin and resides in the North, but its trigram contains an odd line (Yang), representing external Yin and internal Yang. Zhen, Kan, and Gen are the three male trigrams, where Yin exceeds Yang; Xun, Li, and Dui are the three female trigrams, where Yang exceeds Yin. The *Wuzhen Pian* states: "The Sun in the Li position is contrary to the Female; Kan paired with the Moon Palace is indeed the Male." These all illustrate the meaning of Yin-Yang inversion. Therefore, although the female exterior is Yin, her interior corresponds to Yang numbers; although the male exterior is Yang, his interior corresponds to Yin numbers. As Yi He stated in the *Zuo Zhuan* (1st year of Duke Zhao): "Women are Yang objects and act during dark times," also viewing women as Yang. These are matters physicians must observe. 'Geng' is pronounced with a level tone; 'Zhang' with a rising tone, same below.) At the age of fourteen (two sevens), *Tiangui* (a substance promoting reproductive maturity) arrives; the Ren Mai (Conception Vessel) becomes unobstructed, and the Chong Mai (Penetrating Vessel) flourishes; menstruation occurs at regular intervals, enabling conception. ("Tiangui" refers to the Qi of Heavenly One. "Ren" and "Chong" are two of the extraordinary vessels; Ren governs the uterus, and Chong is the Sea of Blood. When Qi is abundant and vessels are patent, menstruation flows, allowing for pregnancy. "Menstruation" means the menstrual blood arrives monthly, waxing and waning in correspondence with the lunar phases. Menstrual blood corresponding to the moon arises from Yin. My commentary notes: Regarding the meaning of Tiangui, various schools interpret it as essence and blood. However, careful reading of this chapter states that at two sevens, Tiangui arrives, and menstruation follows; at two eights, Tiangui arrives, and essence overflows. This clearly shows Tiangui arrives first, followed by essence and blood. They have distinct meanings and cannot be equated. To say Tiangui is essence and blood, or vice versa, confuses the root and branch and is significantly erroneous. 'Gui' is the water of Heaven, a Heavenly Stem name. 'Gan' (Stems) are Yang relative to 'Zhi' (Branches); Yang denotes Qi. 'Gui' is the even counterpart of 'Ren'; even denotes Yin. Thus, Tiangui refers to the Yin Qi of Heavenly One. Qi transforms into water, hence named Tiangui. This is the profound naming by the Sages, overlooked by later scholars. In the human body, this is called Primordial Yin or Primordial Qi. Before birth, this Qi is stored in the parents, known as Pre-heaven Primordial Qi. After birth, this Qi transforms within oneself, known as Post-heaven Primordial Qi. Initially, when Qi is born, True Yin is very slight; only when it becomes abundant does essence and blood flourish. Hence, girls must reach fourteen and boys sixteen before Tiangui arrives. Once Tiangui arrives, girls menstruate regularly, and boys experience seminal emission. This requires sufficient Yin Qi to transform essence and blood. Yin Qi and Yin Essence are like clouds and rain; clouds are the Qi of Yin Essence, rain is the Essence of Yin Qi. Without clouds and mist, there is no rain or snow; without thick clouds, there is no abundant precipitation. Thus, essence is generated by Qi, and Tiangui is undoubtedly the Qi of Heavenly One. Liezi said: "There are those who generate life, and there is that which generates generating life; there are those who form shapes, and there is that which forms shaping shapes." This is what is meant.) At the age of twenty-one (three sevens), Kidney Qi is balanced and uniform; wisdom teeth grow, and physical development reaches its peak. (Kidney Qi here refers to Tiangui. "Balanced" means fullness. "Zhenya" refers to the last teeth to emerge. Since Kidneys govern bones, balanced Kidney Qi allows wisdom teeth to grow and development to peak.) At the age of twenty-eight (four sevens), sinews and bones are firm, hair grows to its maximum length, and the body is in its prime. (The cycle of Tiangui in women ends at seven sevens. At four sevens, one is in the prime of vitality, so the body is strong and hair reaches its peak.) At the age of thirty-five (five sevens), the Yangming Mai (Stomach Meridian) begins to decline; the face starts to wither, and hair begins to fall out. (Women are Yin bodies lacking Yang, so aging begins with the Yangming Mai. The Yangming meridian runs through the face and along the hairline, causing facial withering and hair loss.) At the age of forty-two (six sevens), the San Yang Mai (Three Yang Meridians) decline in the head; the face completely withers, and hair begins to turn white. (The Three Yang meridians are abundant in the face.) At the age of forty-nine (seven sevens), the Ren Mai becomes deficient, the Chong Mai's Qi and Blood decline, Tiangui is exhausted, the "Earthly Way" (menstruation/reproductive function) is blocked, the body deteriorates, and fertility ceases. (At this stage, Chong and Ren blood are scant, and Yin Qi is exhausted, so menstrual flow stops and the female physiological pathway is obstructed. With Tiangui exhausted, the body declines and cannot conceive.)
At the age of eight, a boy's Kidney Qi becomes solid; his hair grows, and his teeth are replaced. (Eight is the number of Shaoyin. Although the male body is fundamentally Yang, he receives the Yin number, indicating that Yang contains Yin. The logic for hair growth and tooth replacement is the same as above.) At the age of sixteen (two eights), Kidney Qi flourishes, Tiangui arrives, essence overflows and is emitted, Yin and Yang harmonize, and conception becomes possible. (The True Yin of both men and women is called Tiangui. Once Tiangui is充盈 (full), essence overflows. Yin and Yang harmonize, enabling procreation. "Zi" generally refers to offspring, whether male or female. My commentary notes: The path to having children requires the union of Yin and Yang for conception. Thus, Heavenly One generates Water, completing with Earth Six; Earth Two generates Fire, completing with Heaven Seven. Therefore, the generation of all things relies on the interaction of Yin and Yang to form shape; this is the Dao of One Yin and One Yang. Regarding the formation of male and female fetuses, Chu Cheng of Northern Qi stated: During intercourse, if Yin blood arrives first and Yang essence follows, the blood opens to wrap the essence, which enters to form bone, resulting in a male fetus; if Yang essence enters first and Yin blood follows, the essence opens to wrap the blood, which enters to form the root, resulting in a female fetus. Qixuanzi stated: Males and females have different Yin-Yang constitutions, and the form of Tiangui as essence and blood also differs. Later physicians followed this view. However, Ma Shi of Xuantai refuted this: Both male and female essence can be called Tiangui. If Wang Bing's commentary says female Tiangui is blood, is male Tiangui also blood? The *I Ching* states: "Male and female intertwine their essence, and all things are transformed." Thus, at the time of intercourse, there is essence; during menstruation, there is blood. It is unheard of to describe intercourse using blood. Books on procreation claiming essence wraps blood or blood wraps essence are incorrect. Ma Shi's view is correct. Li Dongyuan stated: One or two days after menstruation ends, the Sea of Blood is clean; if essence surpasses blood, conception yields a male; four or five days later, blood vessels are flourishing, and essence cannot surpass blood, yielding a female. Zhu Danxi stated: Qian and Kun represent the nature of Yin and Yang; Left and Right represent the pathways of Yin and Yang; Men and Women represent the imagery of Yin and Yang. When Yin and Yang interact, conception condenses. The storage place is called the Uterus, connected by a cord below, with two branches above, divided into two, shaped like a joined bowl, reaching left and right. If essence surpasses blood, Yang dominates, receiving Qi in the left uterus to form a male; if essence does not surpass blood, Yin dominates, receiving Qi in the right uterus to form a female. These differing views may not all be definitive. However, I have my own thoughts. Wang's identification of essence and blood as Tiangui likely stems from the text stating female blood and male essence arrive with Tiangui. While not entirely accurate, the principle is close. Chu's theory is certainly wrong. Intercourse involves the harmony of two essences, not the arrival of blood. After conception, the male initiates Yuan Qi with essence, and the female completes the body with blood. This use of male essence and female blood to describe "interaction" is correct. Describing intercourse as essence wrapping blood is erroneous. The Daoist view of Yang Essence as Tianren (Heavenly Ren) and Yin Essence as Didi (Earthly Gui) is more appropriate. They state: If Tianren arrives first and Didi follows, Didi wraps Tianren to form a male; if Didi arrives first and Tianren follows, Tianren wraps Didi to form a female; if they arrive together, twins are formed; if one is late and one fast, no conception occurs. Tianren and Didi are the primordial essence and Qi of Heaven and Earth. Although this is one view, it is somewhat vague. Li Dongyuan's view suggests conception days after menstruation yields females. However, recent observations show that methods used to conceive males sometimes fail, and males are conceived long after menstruation, contradicting Li. Zhu Danxi's reference to "Left and Right" refers to post-conception states and does not explain the mechanism. "Left and Right" refers to the ascending and descending of Yin and Yang, not necessarily the uterine branches, making it too speculative. To seek the true principle: Qian Dao creates males, Kun Dao creates females; Yang prevailing over Yin makes a male, Yin prevailing over Yang makes a female. This is an unchangeable supreme truth. However, how detailed is the theory of Yin-Yang abundance and deficiency? Old Yang vs. Young Yin determines strength; weak Yang vs. strong Yin determines abundance. Strength without accumulation equals weakness; old age with care equals youth. Timing involves Yin and Yang; neglect leads to Qi decline; following daily rhythms leads to Qi abundance. Like armies, momentum can be lost to premature noise; maintaining stillness waits for the right moment. Using few to defeat many has methods; turning weakness to strength requires skill. Conception depends on the opening and closing of the uterus, not depth; speed is irrelevant. Gender depends on abundance and emptiness, not wrapping; prioritizing sequence is mistaken. Those who practice sexual restraint conceive children who are noble and long-lived; those who indulge conceive children who are turbid and short-lived. Is this not the Dao of Qian and Kun? Those who understand this control gender selection and solve infertility. Children who die young or are weak also result from this. Those desiring children should pay attention to this.) At the age of twenty-four (three eights), Kidney Qi is balanced and uniform; sinews and bones are strong, wisdom teeth grow, and development peaks. (Kidney Water generates Liver Blood, so sinews are strong. Other notes follow the female section.) At the age of thirty-two (four eights), sinews and bones are robust, muscles are full and strong. (This is the peak of male Qi numbers.) At the age of forty (five eights), Kidney Qi declines; hair falls out, and teeth become dry. (Males are Yang bodies lacking Yin, so aging begins with the Kidneys, manifested in hair and teeth.) At the age of forty-eight (six eights), Yang Qi declines in the head; the face withers, and temples turn gray. (Yang Qi refers to the Three Yang Qi. "Ban" is synonymous with "Ban".) At the age of fifty-six (seven eights), Liver Qi declines; sinews cannot move freely, Tiangui is exhausted, essence is scarce, Kidney Qi declines, and the body is extremely fatigued. (Liver governs sinews; Liver decline causes immobility. Kidneys govern bones; Kidney decline causes bodily exhaustion.) At the age of sixty-four (eight eights), teeth and hair fall out. (This is severe decline.)
The Kidneys govern Water and receive the essence of the Five Zang and Six Fu organs to store it. Therefore, only when the Five Zang are abundant can the Kidneys discharge. (The Kidneys are the Water Organ; essence is water. The essence of all Zang and Fu organs is stored in the Kidneys; the Kidneys do not possess essence exclusively. Thus, when the Five Zang are abundant, the Kidneys can discharge.) Now that all Five Zang have declined, sinews and bones are lax, and Tiangui is exhausted. Consequently, hair turns white, the body feels heavy, gait is unsteady, and fertility is lost. (All things decline after reaching full strength; this is the "Heavenly Mandate" mentioned earlier. "Xie" is synonymous with "Xie".)
The Yellow Emperor asked: Some people are old yet have children. Why? Qibo answered: This is because their innate longevity exceeds the norm, their Qi and pulses remain patent, and their Kidney Qi remains abundant. (This is excess innate endowment, i.e., "Caili".) Although such individuals may have children, men do not exceed eight eights (64 years), and women do not exceed seven sevens (49 years), as the essence and Qi of Heaven and Earth are exhausted. (The limit of Tiangui: women exhaust it at seven sevens, men at eight eights. Once essence and Qi are exhausted, further conception is difficult.)
The Yellow Emperor asked: Can practitioners of the Dao, who live to nearly a hundred, still have children? Qibo answered: Practitioners of the Dao can delay aging and preserve physical integrity. Although their chronological age is advanced, they can still reproduce. "Practitioner of the Dao" refers to one who aligns with the Dao. Having aligned with Heaven and Earth, their vitality and lifespan limits are exceptional. Delaying aging and conceiving at an advanced age transcends ordinary limits and cannot be constrained by standard numbers. The main point of this chapter: The Emperor asked about vitality and lifespan limits. Qibo's answer explained vitality through the rise and fall of Tiangui, and lifespan limits through the ages of seven and eight. Even those with strong vitality seem to exceed numerical limits, but their ability to exceed them is still rooted in innate endowment. Only those who accumulate essence, preserve spirit, and align with the Dao through emulation of Heaven and Earth can achieve this.)