阴阳之理，变化无穷，不可尽述。夫言阴阳者，或指天地，或指气血，或指乾坤，
此对待之体，其实阳统乎阴，天包乎地，血随乎气。故圣人作《易》，于干则曰，大哉
干元，乃统天，于坤则曰，至哉坤元，乃顺承天。古人善体《易》义，治血必先理气。
血脱益气，故有补血，不用四物汤之论，如血虚发热，立补血汤，一方以黄 一两为
君，当归四钱为臣，气药多而血药少，使阳生阴长，盖阳统乎阴，血随乎气也。又如失
血暴甚欲绝者，以独参汤一两，顿煎服，纯用气药，斯时也有形之血不能速生，几微之
气，所当急固，使无形生出有形。盖阴阳之妙，原根于无也，故曰无名。天地之始，生
死消长，阴阳之常度，岂人所能损益哉！圣人裁成天地之化，辅相天地之宜，每寓扶阳
抑阴之微权，防未然而治未病也。然生而老，老而病，病而死，人所不能免，但其间
有寿夭长短之差，此歧黄之道所由始，神农尝药，按阴阳而分寒热温凉、辛甘酸苦咸之
辨。凡辛甘者属阳，寒凉者属阴，温热者属阳，酸苦者属阴。阳主生，阴主杀，司命
者，欲人远杀，而就生，甘温者用之辛热者用之，使其跻乎。春风生长之域，一应苦寒
者俱不用，不特苦寒不用，至于凉者亦少用，盖凉者秋气也，万物逢秋风不长矣。或
时当夏令，暑邪侵饮，或过食炙爆辛热而成疾者，暂以苦寒一用，中病即止，终非济生
之品也。
夫人身之阴阳，相抱而不脱，是以百年有常。故阳欲上脱，阴下吸之，不能脱也；
阴欲下脱，阳上吸之，不能脱也，故犹天上地下，阴阳之定位。然地之气，每交于上，
天之气每交于下，故地天为泰，天地为否。圣人参赞天地，有转否为泰之道，如阳气下
陷者，用味薄气轻之品，若柴胡升麻之类，举而扬之，使地道左旋，而升于九天之上；
阴气不降者，用感秋气肃杀而生，若瞿麦 蓄之类，抑而降之，使天道右旋，而入于九
地之下，此东垣补中益气汤，开万事无穷之
利，不必降也，升清则浊自降矣。
春秋昼夜。阴阳之门户。一岁，春夏为阳，秋冬为阴；一月，朔后为阳，望后为
阴；一日，昼为阳，夜为阴；又按十二时。而分五脏之阴阳。医者凭此，以明得病之
源，而施治疗之木。冬至一阳生，夏至一阴生，此二至最为紧要。至者，极也。阴极生
阳，绝处逢生，自无而有阳极生阴，从有而无，阳变阴化之不同也。若春分秋分，不过
从其中平分之耳。其尤肿者独在冬至，故《易》曰∶先王以至日闭关。闭关二字，须
看得广，观《月令》云∶是月斋戒掩身，以待阴阳之所定，则不止闭市之关矣。盖以其
乃一阳生复之始，故最重之也。
《经》曰∶相火之下，水气承之；水位之下，土气承之；土位之下，风气承之；风
位之下，金气承之；金位之下，火气承之；君火之下，阴精承之；亢则害，承乃制也。
如冬至阴盛极，阳生承之，此所谓阴盛亢则害，阳承乃制之。夏至阳盛极，阴生承之，
此所谓阳盛亢则害，阴承乃制之。然冬至一阳生，当渐向暖和，何为腊月大寒，水雪反
盛？夏至一阴生，当渐向清凉，何为三伏溽暑酷热反炽乎？曰∶此将来者进，成功者
退，隐微之际，未易以明也。盖阳伏于下，则逼阴于上，并水气蒸，而坚冰至也；阴盛
于下，则逼阳于上，井水寒而雷电合也。今人病面红、口渴、烦躁、喘咳者，谁不曰火
盛之极，抑孰知其为肾中阴寒所逼乎？以寒凉之药进而毙者，吾不知其几矣，冤哉！
朔望分阴阳者，初一日为死魄，阴极阳生。初三日百 ，十三日而几望，十五则盈
矣。渐至二十以后，月廓空虚，海水东流，人身气血亦随之，女人之经水期月而满，满
则溢，阴极而少阳生，始能受孕，故望以前属阳。
阳一而实，阴二而虚，盖阴之二从阳一所分，故曰秉全体。月有盈亏，人之初生，
纯阳无阴，赖其母厥阴乳哺，而阴始生，是以男子至二八而精通，六十四而精已绝，其
女子至二七而经始行，四十九而经已绝。人身之阴只供三十年之受用，可见阳常有余，
阴常不足。况嗜欲者多，节欲者少，故自幼至老，补阴之功，一日不可缺。此阴字指阴
精而育，不是泛言阴血，今之以四物汤补阴者误也。王节斋云∶水虚成病者十之八九，
火虚成病者十之一二，微得其意矣。褚侍中云∶男子阴已耗，而思色以降其精，则精不
出而内败，小便道涩如淋，阳已痿而复竭之，则大小便牵痛，愈痛则愈便，愈便则愈
痛，然阴中有水有火，水虚者固多，火衰者亦不少，未有精泄已虚，而元汤能独全者。
况阻阳互为其根，议补阴者，须以阳为主，盖无阳则阴无以生也。
男子背阳而负阴，女子背阴而负阳，人身劈中，分阳阴左右。男子右属火而为气，
左属水而为血；女子右属水而左属火。凡人半肢风者，男子多患左，女子多患右，岂非
水不能营耶！
有根阴根阳之妙，不穷其根，阴阳或几乎息矣。谈阴阳者，曰，气血是也。讵知火
为阳气之根，水为阴血之根，盖观之大地，以日为火之精，故气随之，月为水之精，故
潮随之。然此阴阳水火，又同出一根，朝朝禀行，夜夜复命，周流而不息，相偶而不
离。惟其同出一根，而不相离也，故阴阳又各互为其根，阳根于阴，阴根于阳，无阳则
阴无以生，无阴则阳无以化，从阳而引阴，从阴而引阳，各求其属，而穷其根。世人但
知气血为阴阳，而不知水火为阴阳之根，能知水火为阴阳，而误认心肾为水火之真，此
道之所以不明也。试观之天上，金木水火土五星，见在而日月二曜，所以照临于天地间
者，非真阴真阳乎？人身心肝脾肺肾五行具存，而所以营运于五脏六腑之间者，有无形
之相火，行阳二十五度，无形之肾水，行阴二十五度，而其根则原于先天，太甚之真，
此所以为真也。一属有形，便为后天，而非
真矣，非根矣。谓之根如木之根，而枝叶所由以生者也。故人之一气营运升降浮沉者，
皆由生气根于中，而神居之，主阴阳动静之机，其机动而清静者，则生化治，若机动而
烦扰者，则苛疾作、亦由根之固不固也。
既有真阴真阳，何谓假阴假阳？此似是而非，多以误人，如人大热发躁，口渴舌
燥，非阳症乎，视其而色赤，此戴阳也。切其脉尺弱而无力，寸关豁大而无伦，此系阴
盛于下，逼阳于上，假阳之症，以假寒之药，从其性而折之，顷刻平矣。如人恶寒身
不离复衣，手足厥冷，非阴症乎，视其面色滞，切其脉涩，按之细数而有力，此系假寒
之症，寒在皮肤，热在骨髓，以辛凉之剂，温而行之，一汗而愈。凡此皆因真气之不
固，故假者得以乱其真，假阳者不足而示之有余也，假阴者有余而示之不足也。故河间
曰∶夏热太甚，林木流津，火极似水也。冬寒太甚，流水冰坚，阴极似阳也。
阴脉有沉有紧有数，仲景统以微细言之，盖沉必重按，始得紧数，亦在沉细中
见，不似阳症浮大而紧数也。薛氏曰∶人知数为热，不知沉细中见数为寒甚，真阴寒
症，脉常有七八至者，但按之无力而数耳，宜深察之。
有偏阴偏阳者，此气禀也。太阳之人，虽冬月身不须棉，口常饮水，色欲无度，大
便数日一行，芩、连、栀、柏，恬不知怪。太阴之人，虽暑月不离复衣，食饮稍凉，便
沉腹痛泄泻，参、术、姜、桂。时不绝口，一有欲事，呻吟不已。此两等人者，各禀阴
阳之一偏者也。今之为医者，制为不寒不热之方，举世宗之，以为医中王道，岂知人之
受病，以偏得之，用药以救其偏，故以寒治热，以热治寒，此方土之绳墨也。然而苦寒
频进，而积热弥炽，辛热比年，而沉寒益滋者何也？此不知阴阳之属也。《经》曰∶诸
寒之而热者取之阴；诸热之而寒者取之阳，所谓求其属也。故云寒之不寒，是无水也；
热之不热，是无火也。无水者，壮水之主以镇阳光；无火者，益火之原，以消阴翳，达
至理于绳墨之外也。
阴阳者，虚名也。水火者，物理也。寒热者，天之淫气也。水火者，人之真元也。
淫气凑疾，可以寒热药攻之，真天致病，即以水火之真调之，然不求其属，投之不入，
先天水火，原属同宫，火以水为主，水以火为原，故取之阴者，火中求水，其精不竭；
取之阳者，水中寻火，其明不熄，斯大寒大热之病，得其平矣。至于高世立言之士，犹
误认水火为心肾，无怪乎后人之懵懵也。
夫天包地外，地处天中，天地一太极也。以人论之，一阳处于二阴，阴中有阳，
男子阴内阳外，女子阳内阴外，人之一太极也。以物论之，谷属金而糠性热，麦属阳麸
性凉，物物具有一太极也。然二者，阴也，后天之形。一者，阳也，先天之气。神由气
化，气本乎天，故生发吾身者，真阳之气也。形以精成，精生于气，成立吾身者，即
真阴之精也。《经》曰∶女子二七天癸至；男子二八天癸至。又曰∶人年四十，而阴气
已半。所谓阴者，即吾之精造吾之形也。人生全盛之数，惟此前后二十余年越此，则形
体渐衰，故丹溪引∶日月之盈亏，谓阳常有余，阴常不足，立补阴丸为神丹，不知天癸
未至，本由乎气，而阴气自半，亦由乎气，是形虽属阴，而气则从阳也，故人身通体之
温者，阳气也，及其既死，则形存气去，此阳脱在前，阴留在后，生也由乎阳，死也亦
虫乎阳，阳来则生，阳去则殆，阳全阴固，阳脱阴败，故《经》云∶阳气者，若天与
日，失其所，则折寿而不彰。可见人生仗此一点真阳，而为通行不息，孰谓阳常有余，
而以苦寒之味伐之乎？《壮子养生篇》曰∶指穷于为薪火传也，不知其尽也。盖言火之
传于薪，犹神之传于形，薪有尽而必穷，火无形而不灭，自古及今，只是此火传而命
续，田夫养得其极也。世岂知其尽而更生
哉！指尽前薪之理，故火传而不灭。心得纳养之中，故命续而不绝。明夫养生，乃生之
所以生也。
少年人惟恐有火，高年人惟恐无火。无火则运化难而易衰，有火则精神健而难老。
是以火者，人性命之根，况釜底加薪，则釜中津气上腾，而得水上火下，既济之象，但
阳气以潜为贵，潜则弗亢，潜则可久，如盏中加油、则灯愈明，炉中覆灭，则火不熄
也。
天癸之义，每多以精血为解，是不详《内经》之旨也。玩《内经》云∶女子二七
天癸至，月事以时下；男子二八天癸至，精气溢泄。则天癸在先，而后精血继之，天癸
非精血之谓，明矣。天癸者，天一所生之真水也。在人身是谓元阴，即曰元气。人之未
生，此气根于父母，谓之先天元气。人之既生，此气蕴于我身，谓之后天元气。但气之
初生，真阴甚微；及其既盛，精血乃旺。然必真阴足而后精血化，是真阴在精血之先，
精血在真阴之后。夫先天之真阴，为后天精血之根也。若以天癸即精血论，则女子七
七、男子八八而天癸绝，其周身之精血，何以仍营运于营卫之中，而未尝见其相竭也？
则知天癸非精血，明矣。
阴阳的道理，变化无穷，无法完全陈述清楚。所谓阴阳，有时指天地，有时指气血，有时指乾坤，这是相对存在的本体，但实际上阳统摄阴，天包裹地，血跟随气。所以圣人创作《易经》，对于乾卦说：“伟大啊乾元，它统领着天”，对于坤卦说：“美好啊坤元，它顺承着天”。古人善于体会《易经》的含义，治疗血病必须先调理气。血脱证要益气，所以有“补血不用四物汤”的论述。比如血虚发热，创立了补血汤，一方中以黄耆一两为君药，当归四钱为臣药，气药多而血药少，使阳气生发则阴血增长，这是因为阳统摄阴，血跟随气。又如失血极其严重、生命垂危者，用独参汤一两，一次性煎服，纯用补气药，此时有形之血不能迅速生成，只有几微之气应当紧急固护，使无形之气生出有形之血。大概阴阳的奥妙，原本根源于无，所以说无名。天地的开始，生死消长，是阴阳的常规度数，哪里是人所能增减的呢！圣人裁成天地的化育，辅助天地的适宜，每每寓含扶阳抑阴的微妙权变，防备未发生的事，治疗未发生的病。然而人从出生到衰老，从衰老到生病，从生病到死亡，是人所不能避免的，只是其中有寿命长短的差异，这就是岐伯、黄帝医学之道由此开始的缘由。神农尝百草，按照阴阳分为寒热温凉、辛甘酸苦咸的辨别。凡是辛甘味的属于阳，寒凉味的属于阴，温热味的属于阳，酸苦味的属于阴。阳主生长，阴主肃杀，掌管人命的人，希望人们远离肃杀，而趋向生长，所以使用甘温的药，使用辛热的药，使他们进入春风生长的领域，一切苦寒的药都不使用，不仅苦寒的不使用，至于凉性的也很少使用，因为凉性对应秋气，万物遇到秋风就不再生长了。或者时值夏季，暑邪侵袭人体，或者过食烤爆辛热食物而致病者，暂时使用一次苦寒药，中病即止，终究不是济世救人的常用品。
大凡人身上的阴阳，相互抱持而不分离，所以能活到百岁而有常态。所以阳想要向上脱失，阴向下吸引它，就不能脱失；阴想要向下脱失，阳向上吸引它，就不能脱失，这就好像天在上地在下，是阴阳的定位。然而地气常常上交于上，天气常常下交于下，所以地天相交为泰卦，天地不交为否卦。圣人参与赞助天地的化育，有转否为泰的方法，如阳气下陷者，使用味薄气轻的药物，像柴胡、升麻之类，提升它们，使地道左旋，而升于九天之上；阴气不降者，使用感受秋气肃杀而生长的药物，像瞿麦、萹蓄之类，抑制并下降它们，使天道右旋，而入于九地之下，这是李东垣补中益气汤开启万事无穷的利益，不必刻意降浊，升举清阳则浊阴自然下降。
春秋昼夜，是阴阳的门户。一年之中，春夏为阳，秋冬为阴；一月之中，初一之后为阳，十五之后为阴；一日之中，白天为阳，夜晚为阴；又按十二时辰来分五脏的阴阳。医生凭借这些，来明白得病的源头，从而实施治疗的根本。冬至一阳生，夏至一阴生，这两个节气最为紧要。“至”就是极的意思。阴极生阳，绝处逢生，从无到有；阳极生阴，从有到无，这是阳变阴化的不同。如果是春分秋分，不过是从中平分之罢了。其中尤其重要的唯独在冬至，所以《易经》说：“先王在冬至日闭关休息。”闭关二字，必须看得广一些，看《月令》说：“这个月斋戒掩身，以等待阴阳的安定”，那么就不止是关闭市场的关卡了。大概是因为这是一阳复始的开始，所以最重视它。
《内经》说：“相火之下，有水气来承制；水位之下，有土气来承制；土位之下，有风气来承制；风位之下，有金气来承制；金位之下，有火气来承制；君火之下，有阴精来承制；亢盛就会为害，有承制才能制约。”比如冬至阴气极盛，阳气生出来承制它，这就是所谓阴盛亢盛则为害，阳气承制才能制约。夏至阳气极盛，阴气生出来承制它，这就是所谓阳盛亢盛则为害，阴气承制才能制约。然而冬至一阳生，应当逐渐向暖和，为什么腊月大寒，水雪反而兴盛？夏至一阴生，应当逐渐向清凉，为什么三伏天溽暑酷热反而炽盛呢？回答说：这是将来者进，成功者退，在隐微之际，不容易看清。大概阳气伏于下，则逼迫阴气于上，与水气蒸腾，所以坚冰到来；阴气盛于下，则逼迫阳气于上，井水寒冷而雷电合聚。现在人患病面红、口渴、烦躁、喘咳的，谁不说这是火盛到了极点，又有谁知道这是肾中阴寒逼迫所致呢？用寒凉药进治而死亡的，我不知道有多少，冤枉啊！
朔望区分阴阳，初一日为死魄，阴极阳生。初三日眉生，十三日接近满月，十五日就盈满了。渐渐到二十以后，月廓空虚，海水向东流，人身气血也随之变化，女人的月经每月满溢，满了就会溢出，阴极而少阳生，才能受孕，所以望日之前属阳。
阳是一而实，阴是二而虚，大概阴的二从阳的一所分出，所以说秉承全体。月亮有盈亏，人刚出生时，纯阳无阴，依靠母亲厥阴经的乳汁哺育，阴才产生，所以男子到十六岁精通泄精，六十四岁精气已绝；女子到十四岁月经始行，四十九岁月经已绝。人身之阴只供三十年受用，可见阳常有余，阴常不足。何况嗜好欲望的人多，节制欲望的人少，所以从小到老，补阴的功夫，一天不可缺。这个“阴”字指的是阴精而言，不是泛泛谈论阴血，现在用四物汤补阴的是错误的。王节斋说：“水虚成病的十之八九，火虚成病的十之一二”，略微得到了其中的意旨。褚侍中说：“男子阴精已耗，还想通过色欲来降下精气，则精不出而内部败坏，小便道涩滞像淋证一样，阳已痿弱而又去竭它，则大小便牵拉疼痛，越痛就越想排便，越排便就越痛，然而阴中有水有火，水虚固然多，火衰的也不少，没有精气已虚，而元气能够独自保全的。况且阴阳互为其根，议论补阴的，必须以阳为主，因为没有阳则阴无法产生。”
男子背阳而负阴，女子背阴而负阳，人身中间，分左右阴阳。男子右边属火而为气，左边属水而为血；女子右边属水而左边属火。大凡人患半身不遂（偏枯），男子多患左侧，女子多患右侧，难道不是水不能营养吗！
有根阴根阳的奥妙，不探究其根源，阴阳几乎就要息灭了。谈论阴阳的人，说就是气血。哪里知道火是阳气的根，水是阴血的根，大概观察大地，太阳是火的精华，所以气随之运行；月亮是水的精华，所以潮汐随之起伏。然而这阴阳水火，又同出一根，朝朝禀受运行，夜夜复归性命，周流不息，相互偶合而不离开。正因为同出一根，而不离开，所以阴阳又各自互为其根，阳根于阴，阴根于阳，无阳则阴无法产生，无阴则阳无法化生，从阳而引阴，从阴而引阳，各求其所属，而穷究其根源。世人只知道气血是阴阳，而不知道水火是阴阳的根，能知道水火是阴阳，却误认心肾为水火的真体，这就是医道之所以不明朗的原因。试观天上，金木水火土五星，存在而日月二曜，所以照临于天地间者，不就是真阴真阳吗？人心肝脾肺肾五行具存，而所以营运于五脏六腑之间者，有无形之相火，行阳二十五度，无形之肾水，行阴二十五度，而其根源则原于先天太甚之真，这才是真正的。一旦属于有形，就是后天，而非真了，非根了。称为根就像树的根，是枝叶由此产生的地方。所以人的一气营运升降浮沉，都是由生气根于中，而神居之，主宰阴阳动静之机，其机发动而清静者，则生化治理正常，若机发动而烦扰者，则苛疾发作，也是由根的稳固与否决定的。
既然有了真阴真阳，什么叫做假阴假阳？这是似是而非，多以误人，比如人大热发躁，口渴舌燥，不是阳症吗，看他的面色赤红，这是戴阳证。切他的脉尺部弱而无力，寸关部豁大而无伦次，这是系阴盛于下，逼迫阳于上，假阳之症，用假寒性质的药，顺从其本性而折之，顷刻间就平复了。比如人恶寒身体离不开厚衣，手足厥冷，不是阴症吗，看他的面色晦滞，切他的脉涩，按之细数而有力，这是假寒之症，寒在皮肤，热在骨髓，用辛凉的药剂，温而行之，一出汗就好了。凡是这些都是因为真气不固，所以假者得以扰乱真，假阳者是不足而表现出有余，假阴者是有余而表现出不足。所以刘河间说：“夏天热得太厉害，林木流出汁液，火极似水。冬天冷得太厉害，流水结冰坚硬，阴极似阳。”
阴脉有沉、有紧、有数，张仲景统称为微细来说明，大概沉必须重按才得，紧数也在沉细中见到，不像阳症那样浮大而紧数。薛己说：“人们知道数是热，不知道沉细中见数为寒甚，真阴寒症，脉常有七八至的，但按之无力而数罢了，应该深入考察。”
有偏阴偏阳的，这是气禀。太阳之人，虽然冬天身上不需要棉衣，口中常饮水，色欲无度，大便数日一行，服用黄芩、黄连、栀子、黄柏，恬不知怪。太阴之人，虽然夏天离不开厚衣，饮食稍凉，就腹痛泄泻，人参、白术、干姜、肉桂，口中不绝。一旦有房事，呻吟不止。这两等人，各自禀受了阴阳的一偏。现在的医生，制定不寒不热的方子，举世尊崇，以为医中王道，哪里知道人得病，是以偏得之，用药以救其偏，所以以寒治热，以热治寒，这是方土的规矩。然而苦寒频频进服，而积热更加炽盛，辛热连年服用，而沉寒更加滋生的为什么呢？这是不知道阴阳的归属。《内经》说：“各种用寒药治疗而热不退的，取之于阴；各种用热药治疗而寒不退的，取之于阳”，这就是所谓的求其归属。所以说寒之不寒，是无水也；热之不热，是无火也。无水的，壮水之主以镇阳光；无火的，益火之源以消阴翳，达到超越规矩的至理。
阴阳，是虚名。水火，是物理。寒热，是天的淫气。水火，是人的真元。淫气凑集疾病，可以用寒热药攻之，真元致病，就以水火之真调之，然而不求其归属，投药不入，先天水火，原本属于同宫，火以水为主，水以火为原，所以取之阴的，火中求水，其精不竭；取之阳的，水中寻火，其明不熄，这样大寒大热的病，得到平衡了。至于高世栻这样的立言之士，还误认水火为心肾，难怪后人之懵懂。
天包在地外，地处在天中，天地是一个太极。以人论之，一阳处于二阴，阴中有阳，男子阴内阳外，女子阳内阴外，人是小太极。以物论之，谷属金而糠性热，麦属阳而麸性凉，物物都具有一太极。然而二者，是阴，是后天之形。一者，是阳，是先天之气。神由气化，气本乎天，所以生发吾身者，是真阳之气。形以精成，精生于气，成立吾身者，即真阴之精。《内经》说：“女子二七天癸至；男子二八天癸至。”又说：“人年四十，而阴气已半。”所谓阴，就是我的精造就我的形。人生全盛的数目，只有这前后二十余年，超过这个，则形体渐衰，所以朱丹溪引用日月的盈亏，谓阳常有余，阴常不足，创立补阴丸为神丹，不知道天癸未至，本来由于气，而阴气自半，也由于气，是形虽属阴，而气则从阳也，所以人身通体的温者，是阳气也，等到死后，则形存气去，这是阳脱在前，阴留在后，生也由乎阳，死也亦由于阳，阳来则生，阳去则殆，阳全阴固，阳脱阴败，所以《内经》说：“阳气者，若天与日，失其所，则折寿而不彰。”可见人生仗此一点真阳，而为通行不息，谁说阳常有余，而以苦寒之味伐之呢？《庄子·养生主》说：“指穷于为薪，火传也，不知其尽也。”大概言火之传于薪，犹神之传于形，薪有尽而必穷，火无形而不灭，自古及今，只是此火传而命续，农夫养得其极也。世间岂知其尽而更生哉！指尽前薪之理，故火传而不灭。心得纳养之中，故命续而不绝。明夫养生，乃生之所以生也。
少年人惟恐有火，老年人惟恐无火。无火则运化难而易衰，有火则精神健而难老。是以火者，人性命之根，况釜底加薪，则釜中津气上腾，而得水上火下，既济之象，但阳气以潜为贵，潜则弗亢，潜则可久，如盏中加油、则灯愈明，炉中覆灭、则火不熄也。
天癸的意义，每多以精血来解释，是不详《内经》的宗旨。玩味《内经》说：“女子二七天癸至，月事以时下；男子二八天癸至，精气溢泄。”则天癸在先，而后精血继之，天癸非精血之谓，明白了。天癸者，是天一所生之真水也。在人身是谓元阴，即曰元气。人之未生，此气根于父母，谓之先天元气。人之既生，此气蕴于我身，谓之后天元气。但气之初生，真阴甚微；及其既盛，精血乃旺。然必真阴足而后精血化，是真阴在精血之先，精血在真阴之后。夫先天之真阴，为后天精血之根也。若以天癸即精血论，则女子七七、男子八八而天癸绝，其周身之精血，何以仍营运于营卫之中，而未尝见其相竭也？则知天癸非精血，明白了。
The principles of Yin and Yang are infinitely variable and cannot be fully described. When speaking of Yin and Yang, it may refer to Heaven and Earth (Tiandi), Qi and Blood (Qixue), or Qian and Kun (Qiankun); these are relative entities, but in reality, Yang governs Yin, Heaven envelops Earth, and Blood follows Qi. Therefore, when the Sages composed the *I Ching* (Book of Changes), regarding Qian they said, "Great is the Primordial Power of Qian, which leads Heaven," and regarding Kun they said, "Excellent is the Primordial Power of Kun, which follows and receives from Heaven." The ancients were adept at understanding the meaning of the *I Ching*, knowing that treating blood disorders requires first regulating Qi. In cases of blood loss (Xuetuo), one must tonify Qi; hence there is the theory that "tonifying blood does not necessarily use Siwu Tang (Four Substance Decoction)." For example, in cases of fever due to Blood Deficiency (Xue Xu), the formula Bu Xue Tang (Blood Tonifying Decoction) was established, using Huangqi (Astragalus Root) as the sovereign herb (Jun Yao) at 1 liang, and Danggui (Angelica Sinensis Root) as the minister herb (Chen Yao) at 4 qian. There are more Qi-tonifying herbs than Blood-nourishing herbs, allowing Yang to generate so that Yin grows, because Yang governs Yin and Blood follows Qi. Similarly, in cases of massive hemorrhage where life is critical, Dushen Tang (Single Ginseng Decoction) of 1 liang is decocted and taken at once, using purely Qi-tonifying herbs. At this time, tangible Blood cannot be rapidly generated, so the slightest Qi must be urgently secured, allowing the intangible to produce the tangible. The wonder of Yin and Yang originates from non-being; thus it is said "Nameless." The beginning of Heaven and Earth, the cycle of life and death, waxing and waning, are the constant measures of Yin and Yang, which humans cannot add to or subtract from! The Sages shaped the transformations of Heaven and Earth, assisted their appropriateness, and always embedded the subtle balance of supporting Yang and suppressing Yin, preventing what has not yet occurred and treating disease before it arises. However, birth, aging, illness, and death are unavoidable for humans, though there are differences in longevity. This is how the Way of Qibo and Huangdi began. Shennong tasted herbs, classifying them by Yin and Yang into Cold, Hot, Warm, Cool, Pungent, Sweet, Sour, Bitter, and Salty. Pungent and Sweet belong to Yang; Cold and Cool belong to Yin; Warm and Hot belong to Yang; Sour and Bitter belong to Yin. Yang governs growth, Yin governs destruction. Those who manage human life wish for people to avoid destruction and embrace growth, so they use Sweet-Warm and Pungent-Hot herbs to bring people into the realm of spring wind growth. All Bitter-Cold herbs are unused; not only are Bitter-Cold herbs unused, but Cool herbs are also rarely used, because Cool corresponds to Autumn Qi, and all things cease to grow in autumn winds. If during summer, Summer-Heat pathogenic factors invade, or if illness results from overeating roasted, fried, pungent, and hot foods, Bitter-Cold herbs may be used temporarily, stopping as soon as the disease is cured; they are ultimately not standard items for saving lives.
In the human body, Yin and Yang embrace each other without separating, allowing one to live a normal lifespan of a hundred years. Thus, if Yang tends to float upward and escape, Yin draws it down from below, preventing escape; if Yin tends to sink downward and escape, Yang draws it up from above, preventing escape. This is like Heaven above and Earth below, the fixed positions of Yin and Yang. However, Earth's Qi often rises to meet Heaven, and Heaven's Qi often descends to meet Earth; thus Di Tian Tai (Earth over Heaven, Peace) occurs when they interact, while Tian Di Pi (Heaven over Earth, Stagnation) occurs when they do not. The Sages participated in assisting Heaven and Earth, having methods to transform Pi into Tai. For those with sinking Yang Qi, light-flavored and light-aromatic herbs such as Chaihu (Bupleurum Root) and Shengma (Cimicifugae Rhizome) are used to lift and raise, causing Earth's Dao to rotate left and ascend to the highest heavens; for those with descending-deficient Yin Qi, herbs that respond to the肃杀 (severe/clearing) Qi of Autumn, such as Qumai (Dianthus Herba) and Pianxu (Polygoni Avicularis Herba), are used to suppress and descend, causing Heaven's Dao to rotate right and enter the deepest earth. This is the benefit opened by Li Dongyuan's Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction): there is no need to forcibly descend turbidity; raising the Clear ensures the Turbid descends naturally.
Spring and Autumn, Day and Night, are the gates of Yin and Yang. In a year, Spring and Summer are Yang, Autumn and Winter are Yin; in a month, after the New Moon (Shuo) is Yang, after the Full Moon (Wang) is Yin; in a day, Day is Yang, Night is Yin; further divided by the twelve double-hours to correspond to the Yin and Yang of the Five Zang Organs. Physicians rely on this to understand the source of disease and apply treatment principles. At Winter Solstice (Dongzhi), one Yang is born; at Summer Solstice (Xiazhi), one Yin is born. These two solstices are most critical. "Zhi" means extreme. Extreme Yin generates Yang, finding life in death, from non-being to being; Extreme Yang generates Yin, from being to non-being, differing in Yang transformation and Yin change. Equinoxes merely divide the middle equally. The most significant is Winter Solstice, hence the *I Ching* says: "The Ancient Kings closed the passes on the Solstice days." "Closing the passes" must be understood broadly; observing the *Monthly Ordinances*: "In this month, fast and conceal oneself, waiting for the determination of Yin and Yang," implies it is not just closing market gates. It is most valued because it marks the beginning of the return of one Yang.
The *Classic* states: "Below Xiang Huo (Ministerial Fire), Shui Qi (Water Qi) supports it; below Water position, Tu Qi (Earth Qi) supports it; below Earth position, Feng Qi (Wind Qi) supports it; below Wind position, Jin Qi (Metal Qi) supports it; below Metal position, Huo Qi (Fire Qi) supports it; below Jun Huo (Sovereign Fire), Yin Jing (Yin Essence) supports it. Excess causes harm, support brings control." For example, at Winter Solstice, Yin is extremely abundant, and Yang is born to support/control it; this is "Yin excess leads to harm, Yang support controls it." At Summer Solstice, Yang is extremely abundant, and Yin is born to support/control it; this is "Yang excess leads to harm, Yin support controls it." Yet at Winter Solstice, when one Yang is born, warmth should gradually increase, why is La Yue (the twelfth lunar month) extremely cold with heavy snow? At Summer Solstice, when one Yin is born, coolness should gradually increase, why are the Sanfu (Dog Days) humid and intensely hot? The answer is: what is coming advances, what has succeeded retreats; in the hidden and subtle moments, it is not easy to clarify. Generally, when Yang hides below, it forces Yin upward, steaming with Water Qi, leading to hard ice; when Yin is abundant below, it forces Yang upward, making well water cold and thunderstorms occur. Today, patients with red face, thirst, restlessness, wheezing, and coughing are universally said to have extreme Fire, but who knows it is forced upward by Kidney Yin-Cold? How many have died from administering Cold-Cool medicines? Unjust!
New Moon and Full Moon distinguish Yin and Yang. The first day is "Dead Soul," Yin extreme, Yang born. By the third day, the crescent appears; by the thirteenth, nearly full; by the fifteenth, full. Gradually after the twentieth, the moon's outline empties, seawater flows east, and human Qi and Blood follow suit. Women's menstruation fills monthly; when full, it overflows. Yin extreme, Shaoyang (Lesser Yang) is born, enabling conception; thus, before the Full Moon belongs to Yang.
Yang is One and Solid; Yin is Two and Hollow. Yin's Two derives from Yang's One, hence called "holding the complete form." The moon waxes and wanes. Humans are born Pure Yang without Yin, relying on the mother's Jueyin (Liver Meridian) breast milk for Yin to begin generating. Thus, males reach seminal emission at sixteen (2x8) and essence ceases at sixty-four (8x8); females begin menstruation at fourteen (2x7) and it ceases at forty-nine (7x7). Human Yin serves only thirty years; thus, Yang is often in excess, Yin is often deficient. Moreover, those indulging desires are many, those restraining them are few. Hence, from youth to old age, the work of tonifying Yin must never cease. Here, "Yin" refers to Yin Essence (Jing), not generically to Yin Blood. Using Siwu Tang (Four Substance Decoction) to tonify Yin today is erroneous. Wang Jiezhai said: "Eight or nine out of ten diseases arise from Water Deficiency, one or two from Fire Deficiency," slightly grasping the intent. Chu Shizhong said: "Males' Yin Essence is already depleted, yet they seek sexual release, causing essence to fail internally, urine passage obstructed like strangury. If Yang is already impotent and further exhausted, large and small bowel movements cause pain; the more painful, the more one defecates; the more one defecates, the more painful. Within Yin there is Water and Fire; Water deficiency is common, but Fire decline is also frequent. No one whose essence is depleted can preserve Yuan Qi alone. Since Yang and Yin root each other, discussing Yin tonification must prioritize Yang, for without Yang, Yin cannot generate."
Males carry Yang on the back and Yin on the front; females carry Yin on the back and Yang on the front. In the human body, left and right divide Yin and Yang. Males: Right belongs to Fire and is Qi; Left belongs to Water and is Blood. Females: Right belongs to Water; Left belongs to Fire. Hemiplegia (Ban Zhi Feng) affects males mostly on the left, females mostly on the right; is this not because Water fails to nourish?
There is the subtlety of rooting Yin in Yang and Yang in Yin. Without exploring the root, Yin and Yang would almost cease. Those discussing Yin and Yang say it is Qi and Blood. But do they know Fire is the root of Yang Qi, and Water is the root of Yin Blood? Observing the earth: the Sun is the essence of Fire, so Qi follows it; the Moon is the essence of Water, so tides follow it. However, this Yin-Yang and Water-Fire share one root, receiving execution daily, returning to life nightly, flowing endlessly, paired and inseparable. Because they share one root and do not separate, Yin and Yang mutually root each other: Yang roots in Yin, Yin roots in Yang. Without Yang, Yin cannot generate; without Yin, Yang cannot transform. Draw Yin from Yang, draw Yang from Yin, seek their belonging, and exhaust their roots. People only know Qi and Blood are Yin and Yang, not knowing Water and Fire are the roots of Yin and Yang. Knowing Water and Fire are Yin and Yang, but mistakenly identifying Heart and Kidney as the true Water and Fire, this is why the Dao remains unclear. Observe the sky: the five planets exist, but the Sun and Moon illuminate the world; are they not True Yin and True Yang? In the human body, the Five Elements of Heart, Liver, Spleen, Lung, and Kidney exist, but what operates among the Zang and Fu organs is Formless Xiang Huo (Ministerial Fire), moving through Yang twenty-five degrees, and Formless Kidney Water, moving through Yin twenty-five degrees. Their root originates from the Pre-heaven True Essence. This is what is truly real. Once it becomes tangible, it is Post-heaven, not True, not Root. Calling it "Root" is like a tree's root, from which branches and leaves grow. Thus, the movement, circulation, ascending, descending, floating, and sinking of human Qi all stem from Sheng Qi (Vital Qi) rooted within, with Shen (Spirit) residing there, governing the mechanism of Yin-Yang movement and stillness. If the mechanism moves with clarity and stillness, generation and transformation are regulated; if the mechanism moves with disturbance, severe diseases arise. This depends on whether the root is solid.
Since there is True Yin and True Yang, what are False Yin and False Yang? These are deceptive and often mislead people. For instance, a patient with high fever, agitation, thirst, and dry tongue—surely a Yang syndrome? But if the face is red, this is Dai Yang (Floating Yang). If the pulse at the Chi position is weak and powerless, while Cun and Guan positions are vast and irregular, this indicates Yin abundance below forcing Yang upward—a False Yang syndrome. Using medicines with false-cold properties to follow its nature and subdue it will calm it instantly. Conversely, a patient fearing cold, wrapped in layers, with cold limbs—isn't this a Yin syndrome? But if the complexion is dull, the pulse is choppy, fine, rapid, and forceful upon pressure, this is a False Cold syndrome: Cold in the skin, Heat in the marrow. Using Pungent-Cool agents, administered warmly, will cure it with one sweat. All these occur because True Qi is insecure, allowing the False to disturb the True. False Yang shows excess where there is deficiency; False Yin shows deficiency where there is excess. Liu Hejian said: "Extreme summer heat makes trees weep sap; extreme Fire resembles Water. Extreme winter cold makes water freeze hard; extreme Yin resembles Yang."
Yin pulses include Chen (Deep), Jin (Tight), and Shu (Rapid). Zhang Zhongjing summarizes them as Wei Xi (Fine and Thin). Chen requires heavy pressure to feel; Jin and Shu are seen within Chen and Xi, unlike Yang syndromes which are Fu Da (Floating and Large) with Jin Shu. Xue Ji said: "People know Shu indicates Heat, but do not know Shu within Chen and Xi indicates severe Cold. In True Yin-Cold syndromes, the pulse often beats seven or eight times per breath, but is powerless upon pressure. One must examine deeply."
There are those biased toward Yin or Yang, due to constitutional endowment. Taiyang individuals: even in winter, they need no cotton, drink water constantly, indulge in sex, have bowel movements every few days, and take Huangqin, Huanglian, Zhizi, Huangbai without surprise. Taiyin individuals: even in summer, they need thick clothes; slight cooling of food/drink causes abdominal pain and diarrhea; they constantly consume Renshen, Baizhu, Jiang, Rougui. Upon sexual activity, they groan incessantly. These two types embody a bias of Yin or Yang. Modern physicians create neutral (neither cold nor hot) formulas, revered by the world as the "King's Way" of medicine. But they do not know that disease arises from bias, and medicine must correct bias; thus, treating Heat with Cold, and Cold with Heat, is the standard rule. Yet why does frequent Bitter-Cold intake intensify accumulated Heat, and annual Pungent-Hot intake deepen chronic Cold? This is ignorance of Yin-Yang belonging. The *Classic* says: "For all cases treated with Cold that remain hot, treat the Yin; for all cases treated with Heat that remain cold, treat the Yang." This is seeking the belonging. Thus, "Cold does not resolve Cold" means Water Deficiency; "Heat does not resolve Heat" means Fire Deficiency. For Water Deficiency, strengthen the master of Water to suppress Solar Flare; for Fire Deficiency, augment the source of Fire to dissipate Yin Shadows, reaching truth beyond mere rules.
Yin and Yang are empty names; Water and Fire are physical realities; Cold and Heat are excessive Heavenly Qi; Water and Fire are human True Yuan. Pathogenic excessive Qi causing disease can be attacked with Cold/Hot medicines; True Yuan causing disease is regulated by True Water/Fire. However, without seeking belonging, medicine will not penetrate. Pre-heaven Water and Fire originate in the same palace; Fire takes Water as master, Water takes Fire as source. Thus, seeking Yin means seeking Water within Fire, ensuring essence does not deplete; seeking Yang means seeking Fire within Water, ensuring brightness does not extinguish. Thus, extreme Cold and Heat diseases achieve balance. Scholars like Gao Shili still mistake Water/Fire for Heart/Kidney, no wonder later generations are confused.
Heaven envelops Earth; Earth is within Heaven; Heaven and Earth are one Taiji. Regarding humans: One Yang resides within Two Yins, Yang within Yin. Males: Yin inside, Yang outside; Females: Yang inside, Yin outside. This is the human Taiji. Regarding objects: Grain belongs to Metal, bran is Hot; Wheat belongs to Yang, husk is Cool. Every object possesses a Taiji. The two (Yin) are Post-heaven forms; the One (Yang) is Pre-heaven Qi. Spirit transforms from Qi; Qi originates from Heaven. Thus, what generates our body is True Yang Qi. Form is formed by Essence; Essence generates from Qi. What establishes our body is True Yin Essence. The *Classic* says: "Females at 2x7 Tian Gui arrives; Males at 2x8 Tian Gui arrives." Also: "At age 40, Yin Qi is half gone." The "Yin" here refers to my Essence forming my Form. The peak of human life is only these twenty-plus years. After this, the form declines. Thus, Zhu Danxi cited the waxing/waning of sun and moon, stating Yang is often in excess, Yin often deficient, establishing Buyin Wan (Yin Tonifying Pill) as a divine medicine. But he did not know that before Tian Gui arrives, it depends on Qi; and Yin Qi halving at 40 also depends on Qi. Although Form belongs to Yin, Qi follows Yang. Thus, the warmth of the whole body is Yang Qi. After death, form remains, Qi departs; Yang escapes first, Yin remains. Life depends on Yang, death depends on Yang. Yang comes = life; Yang goes = danger. Yang complete, Yin solid; Yang escaped, Yin ruined. Hence the *Classic* says: "Yang Qi is like Heaven and the Sun; losing its proper place shortens life and obscures vitality." Clearly, human life relies on this point of True Yang for continuous circulation. Who says Yang is often in excess and should be attacked with Bitter-Cold flavors? The *Zhuangzi* says: "The finger is exhausted like firewood; the fire is transmitted, unknown to end." This means fire transmitted to wood is like spirit transmitted to form. Wood ends, but fire is formless and undying. From ancient times to now, only this fire transmits and life continues. Farmers understand this perfectly. Does the world know it regenerates after exhaustion? Understanding the principle of the previous firewood, the fire transmits undying. Receiving nourishment in the heart, life continues uninterrupted. Understanding health preservation is the reason for life.
Youth fear Fire; Old age fears lack of Fire. Lack of Fire makes transformation difficult and decline easy; presence of Fire makes spirit robust and aging slow. Thus, Fire is the root of human life. Adding fuel to the pot raises moisture and Qi, creating the image of Ji Ji (Completion/Intersection of Water and Fire). Yang Qi values hiding/submerging; hidden, it does not flare; hidden, it lasts long. Like adding oil to a lamp, it shines brighter; covering coals in a stove, the fire does not extinguish.
The meaning of Tian Gui is often explained as Jing and Blood, failing to detail the intent of the *Nei Jing*. Studying the *Nei Jing*: "Females at 2x7 Tian Gui arrives, menstruation按时; Males at 2x8 Tian Gui arrives, essence overflows." Tian Gui comes first, then Jing and Blood follow. Tian Gui is not Jing and Blood, clearly. Tian Gui is the True Water generated by Tian Yi. In the body, it is called Yuan Yin (Primary Yin) or Yuan Qi (Primary Qi). Before birth, this Qi roots in parents, called Pre-heaven Primary Qi. After birth, this Qi accumulates in the body, called Post-heaven Primary Qi. Initially, True Yin is very slight; when mature, Jing and Blood flourish. But True Yin must be sufficient before Jing and Blood transform; True Yin precedes Jing and Blood, Jing and Blood follow True Yin. Pre-heaven True Yin is the root of Post-heaven Jing and Blood. If Tian Gui were Jing and Blood, then at 7x7 (females) and 8x8 (males) when Tian Gui ceases, why does周身 (whole-body) Jing and Blood still circulate in Ying and Wei without depletion? Thus, Tian Gui is not Jing and Blood, clearly.