凡病有名有症。有机有情。如中风。伤寒。温暑。湿 等类。此为名也。外有头痛。身热。腰痛。内有喘咳。
烦渴。吐利。胀满。所谓症也。其间在表在里。有汗无汗。脉沉脉浮。有力无力。是其机也。此时恶寒。恶热。苦满。
喜呕。能食。不能食。欲寐不得卧。或饮水数升。或嗽水不欲咽。皆病情也。因名立方者。粗工也。据症定方者。中工
也。于症中审病机。察病情者。良工也。仲景制方不拘病之命名。惟求症之切当。知其机。得其情。凡中风伤寒杂病。
宜主某方。随手拈来。无不合法。此谓医不执方也。今谈仲景方者。皆曰桂枝汤。治中风不治伤寒。麻黄汤。治伤寒不
治中风。不知仲景此方主何等症。又不察仲景何症用何等药。只在中风伤寒二症中相较。青龙白虎命名上敷衍。将仲景
活方活法。为死方死法矣。
仲景立方。精而不杂。其中以六方为主。诸方从而加减也。凡汗剂。皆本桂枝。吐剂皆本栀豉。攻剂皆本承气。和
剂皆本柴胡。寒剂皆本泻心。温剂皆本四逆。浑而数之。为一百十三方者。未之审也。
六经各有主治之方。而他经有互相通用之妙。如桂枝麻黄二汤。为太阳营卫设。而阳明之病在营卫者亦用之。真武
汤。为少阴水气设。而太阳之汗后亡阳者亦用之。四逆汤。为太阴下利清谷设。太阳之脉反沉者亦宜之。五苓散。为太
阳消渴水逆设。阳明之饮水多者亦宜之。猪苓汤。为少阴下利设。阳明病小便不利者亦宜之。抵当汤。为太阳瘀血在里
设。阳明之蓄血亦用之。瓜蒂散。为阳明胸中痞硬设。少阴之温温欲吐者亦用之。合是症。便用是方。方各有经。而用
可不拘。是仲景法也仲景立方。只有表里寒热虚实之不同。并无伤寒杂病中风之分别。且风寒有两汤迭用之妙。表里有
两方更换之奇。或以全方取胜。或以加减奏功。前人论方不论症。故反以仲景方为难用耳。
桂枝汗剂中第一品也。麻黄之性。直达皮毛。生姜之性。横散肌肉。故桂枝佐麻黄。则开玄府而逐卫分之邪。令无
汗者有汗而解。故曰发汗。桂枝率生姜。则开腠理而驱营分之邪。令有汗者复汗而解。故曰解肌。解肌。解肌肉之邪也。
正在营分。何立三纲者。反云麻黄主营。桂枝主卫耶。麻黄汤。不言解肌。而肌未尝不解。桂枝汤之解肌。正所以发汗。
要知桂枝麻黄是发汗分浅深之法。不得以发汗独归麻黄。不得以解肌与发汗对讲。前人论方不论药。祗以二方为谈柄。
而置之不用也。
凡风寒中人。不在营卫。即在腠理。仲景制桂枝汤。调和营卫。制柴胡汤。调和腠理。观六经症。知仲景独出桂枝
症。柴胡症之称。见二方任重。不可拘于经也。惟太阳统诸阳之气。六经表症咸属于太阳。故柴胡汤得与桂枝汤对待于
太阳之部。桂枝本为太阳风寒设。凡六经初感之邪。未离营卫者悉宜之。柴胡本为少阳半表。凡三阳在表之邪。还在腠
理者悉宜之。仲景一书。最重二方。所以自为桂枝注释。又为小柴胡注释。桂枝有疑似症。柴胡亦有疑似症。桂枝有坏
症。柴胡亦有坏症。桂枝症罢。桂枝不中与矣。而随症治法。仍不离桂枝方加减。柴胡症罢。柴胡不中与矣。而设法救
逆。仍不出柴胡汤加减。
麻黄汤症。热全在表。桂枝之自汗。大青龙之烦躁。皆兼里热。仲景于表剂中。便用寒凉以清里。自汗是烦之兆。
烦是躁之征。汗出则烦得外泄。故不躁。宜用微寒酸苦之味以和之。汗不出。则烦不得泄。故躁。宜用大寒坚重之品以
清之。夫芍药石膏是里药。今人见入表剂中。不审表中有里。因生疑畏。当用不用。至热并阳明。而班黄狂乱。是不任
大青龙之故也。仲景于太阳经中。用石膏以清胃火。是预保阳明之先着。加姜枣以培中气。又虑夫转属太阴矣。
青龙柴胡。皆是两解表里之剂。小青龙重在里症。小柴胡重在表症。故小青龙加减。麻黄可去。小柴胡加减。柴胡
独存。盖小青龙重在半里之水。小柴胡重在半表之热也。
小青龙。治伤寒未解之水气。故用温剂汗而发之。十枣汤。治中风已解之水气。故用寒剂引而竭之。此寒水风水之
异治也。小青龙之水。动而不居。五苓散之水。留而不行。十枣汤之水。纵横不羁。大陷胸之水。痞硬坚满。真武汤之
水。四肢沉重。水气为患不同。所以治法各异。
林亿云。泻心本名理中黄连人参汤。盖泻心疗痞。正是理中处。当知仲景用理中有寒热两法。一以扶阳。一以益阴
也。
邪在营卫之间。惟汗是其出路。故立麻黄桂枝二方。邪在胸腹之间。惟吐是其出路。故立瓜蒂栀豉二方。瓜蒂散主
胸中痞硬。治在上焦栀豉汤主腹满而喘。治兼中焦。犹麻黄汤之主皮肤。桂枝汤之主肌肉也。瓜蒂散峻剂也。犹如麻黄
汤之不可轻用。栀豉汤轻剂也。犹如桂枝汤可更用而无妨。故太阳表剂。多从桂枝汤加减。阳明表剂。多从栀子汤加减。
阳明用栀子。犹太阳用桂枝。既可用之以驱邪。即可用之以救逆。今人但知汗为解表。而不知吐亦为解表。知吐中便能
发散之说。不知所以当吐之义。故于仲景大法中。取其汗下遗其吐法耳。
少阳为枢。不全在里不全在表。仲景本意重里。而柴胡所主又在半表。故必见半表病情。乃得从柴胡加减。如悉入
在里。则柴胡非其任矣。故柴胡称解表之方。
小柴胡虽治在半表。实以理三焦之气。所以称枢机之剂。如胸满。胸中烦。心烦。心下悸。喜呕。喝咳。是上焦无
开发之机也。腹痛。胁下痞硬。不欲饮食。是中焦废转运之职也。小便不利。是下焦失决渎之任也。皆因邪气与正气相
搏而然。用人参扶三焦之正气。壮其枢耳。
四逆为太阴主方。而诸经可以互用。在太阴本经。固本以逐邪也。用于少阴。温土以制水也。用于厥阴。和土以生
木也。用于太阳。益火以扶元阳也。惟阳明胃实。少阳相火。非所宜耳。
少阴病四五日。腹痛。小便不利。下利不止。若四肢沉重疼痛者。为下焦水郁。用真武汤。是引火归元法。若便脓
血者。为下焦火郁。用桃花汤。是升阳散火法。此因坎中阳虚。不得以小便不利作热治。
少阴病。二三日。心中烦。不得卧者。病本在心。法当滋离中之真水。随其势之润下。故君黄连之苦寒以火泄之。
四五日小便不利。下脓血者。病本在肾。法当升坎中之少火。顺其性之炎上。故佐干姜之苦温以发之。此伏明之火与升
明之火不同治。
少阴心烦欲寐。五六日欲吐不吐。自利而渴。小便色白者。是下焦虚寒。不能制火。宜真武汤。以温下焦之肾水。
下利六七日。咳而呕渴。心烦不眠。是上焦虚热。水精不布。宜猪苓以通上焦之津液。
厥阴下利。用白头翁汤。升阳散火。是火郁达之也。制乌梅丸以救火。是曲直作酸之义。佐苦寒以和阴。主温补以
存阳。是肝家调气之法也。乌梅丸。治伤寒之厥利与久利。故半兼温补。白头翁汤。主中风之热利与下重。故专于凉散。
小柴胡为少阳主方。乌梅丸为厥阴主方。二方虽不同。而寒温互用。攻补兼施之法相合者。以脏腑相连。经络相贯。
风木合气。同司相火故也。其中皆用人参。补中气以固本逐邪。而他味俱不相袭者。因阴阳异位。阳宜升散。故主以柴
胡。阴宜收降。故主以乌梅。阳主热。故重在寒凉。阴主寒。故重用辛热。阳以动为用。故汤以荡之。其症变幻不常。
故柴胡有加法。阴以静为体。故丸以缓之。其症有定局。故乌梅无加减法也。手足厥逆之症。有寒有热。有表有里。四
逆散。解少阴之里热。当归四逆散。散厥阴之表寒。通脉四逆。挽少阴真阳之将亡。茯苓四逆。留太阳真阴之欲脱。四
方更有轻重浅深之别也。
按发表攻里。乃御邪之长技。盖表症皆因风寒。如表药用寒凉。则表热未退。而中寒又起。所以表药必用桂枝。发
表不远热也。
然此为太阳表热言耳。如阳明少阳之发热。则当用柴芩栀豉之类主之。里热皆因郁热。下药不用苦寒。则瘀热不除。
而邪无出路。所以攻剂必用大黄。攻里不远寒也。然此为阳明胃热言耳。如恶寒痞硬。阳虚阴结者。又当以姜附巴豆之
类兼之矣。
麻黄桂枝。太阳阳明表之表药。瓜蒂栀豉。阳明里之表药。小柴胡。少阳半表之全药。太阴表药。桂枝汤。少阴表
药。麻黄附子细辛汤。厥阴表药。当归四逆汤。六经之用表药。为六经风寒之出路也。
膀胱主水。为太阳之里。十枣五苓。为太阳水道之下药。胃腑主谷。为阳明之里。三承气。为阳明谷道之下药。胆
腑主气。为少阳之里。大柴胡。为少阳气分之下药。此三阳之下药三阳实邪之出路也。
大肠小肠。俱属于胃。胃家实。则二肠俱实矣。若三分之。则调胃承气。胃家之下药。小承气。小肠之下药。大承
气。大肠之下药。戊为燥土。庚为燥金。故加芒硝以润之也。
桂枝加大黄。太阳转属阳明之下药。桂枝加芍药。太阳转属太阴之下药。凡下剂兼表药者。以未离于表也。柴胡加
芒硝汤。少阳转属阳明之下药。大柴胡下少阳无形之邪。柴胡加芒硝。下少阳有形之邪。桂枝加芍药。下太阴无形之邪。
三物白散。下太阴有形之邪。四逆散。下少阴厥阴无形之邪。承气。下诸经有形之邪也。下剂之轻者。只用气分药。下
剂之重者。兼用血分药。酸苦涌泄。下剂之轻者。故芍药枳实为轻剂。咸苦涌泄。下剂之重者。故大黄芒硝为重剂。
仲景用攻下二字。不专指大便。凡与桂枝汤。欲攻其表。此指发汗言。表解者乃可攻之。指利水言。有热属脏者攻之。指清火言。寒湿在里不可下。指利水言。以有热故也。当以法下之。指清火言也。
仲景下剂。只重在汤。故曰医以丸药下之。非其治也。观陷胸抵当二丸。仍用水煮是丸。复为汤化。而连滓服。则
势力更猛于汤散矣。当知仲景方以铢两分数者。非外感方。丸药如梧桐子大。每服数十丸者。不是治外感法。仲景制
方疗病。随立方禁于后。使人受其功。不蹈其弊也。如用发表药。一服汗者。停后服。若脉浮紧。发热汗出者。不可与
桂枝。若脉微弱。汗出恶风者。不可服大青龙。脉浮发热无汗。表不解者。不可与白虎。诸亡血虚者。不可用瓜蒂。
病患旧微溏者。不可与栀子豉汤。阳明病汗多者。不可与猪苓汤。外未解。其热不潮者。未可与承气。呕家不可与建中。
观种种方禁。当知仲景立方。慎重之心也。
仲景加减中有深意。如腹中痛者。少阳加芍药。少阴加附子。太阴加人参。如心下悸者。少阴加桂枝。少阳加茯苓。
若渴者。太阳加栝蒌根。人参。太阴加白术。仲景于加减中。分阴阳表里如此。故细审仲景方。知随症立方之妙。理会
仲景加减法。知其用药取药之精。小青龙设或然五症。加减法内。即备五方。小柴胡设或然七症。即加减七方。要知仲
景有主治之方。如桂枝麻黄等方是也。有方外之方。如桂枝汤。加附子。加大黄是也。有方内之方。如青龙真武辈之有
加减是也。仲景书。法外有法。方外有方。何得以三百九十七法。一百一十三方拘之也耶。昔岐伯创七方以制病。仲景
更穷其病之变幻。而尽其精微。如发表攻里乃逐邪大法。而发表攻里之方。各有大小。如小青龙柴胡陷胸承气是也。夫
发表既有麻黄桂枝方矣。然有里邪夹表而见者。治表不及里。非法也。而里邪又有夹寒夹热之不同。故制小青龙。以治
表热里寒。制大青龙以治表寒里热。是表中更兼解里。必如坏病之先里后表。先表后里之再计也。然大小青龙。即麻桂二汤之变。 足以解营卫之表。不足以驱腠理之邪。且邪留腠理之间。半表之往来寒热虽同。而半表又有夹虚夹实之悬殊。因制小柴胡以防半里之虚。大柴胡以除半里之实。是表中便见和里。岂若后人先攻后补。先补后攻之斟酌也。攻里既有调胃承气矣。然里邪在上焦者。有夹水夹痰之异。在中焦者。有初硬后溏。燥屎定硬之分。非调胃一剂所能平也。因制小陷胸以清胸膈之痰。大陷胸以下胸膈之水。小承气以试胃家之失气。大承气以攻肠胃之燥屎。方有分寸。邪去而元气无伤。不致有顾此遗彼。太过不及之患也。按发表攻里之方。各有缓急之法。如麻黄汤。大承气。汗下之急剂也。桂枝。即发表之缓剂。其用桂枝诸法。是缓汗中更有轻重矣。小承气。下药之缓剂也。曰少与之。令小安。曰微和胃气。曰不转失气者令更与之。其调胃承气。则下剂之尤缓者也。曰少少温服之。且不用气分药。更加甘草。是缓下中亦有差
别矣。若夫奇偶之法。诸方既已备见。
桂枝二方。各半之偶。桂枝二麻黄一之奇。是奇偶中各有浅深也。服桂枝汤已。须更吃稀粥为复方矣而更有取小柴
胡服一升加芒硝之复。是复方中又分汗下二法矣。若白散之用复方更异。不利。进热粥一杯。利不止。进冷粥一杯。是
一粥又寓热泻冷补之二法也。
病有虚实相关。寒热夹杂。有时药力所不能到者。仲景或针或灸以治。自后世针药分为两途。岂知古人刺药相须之
凡是疾病，都有名称和症状。有机理和病情。比如中风、伤寒、温病、暑病、湿病等类别，这是疾病的名称。外在表现有头痛、身热、腰痛；内在表现有喘咳、烦渴、呕吐腹泻、胀满，这些称为症状。其中在表还是在里，有汗还是无汗，脉象沉还是浮，有力还是无力，这是疾病的机理。此时恶寒、恶热、胸胁苦满、喜欢呕吐、能进食或不能进食、想睡觉却睡不着，或者喝几升水，或者漱口但不想咽下，这些都是病情的具体表现。根据名称来制定方剂的，是粗劣的医生；根据症状来确定方剂的，是中等的医生；在症状中审察病机、观察病情的，才是优秀的医生。张仲景制定方剂不拘泥于疾病的命名，只追求症状的准确对应。掌握了病机，了解了病情，凡是中风、伤寒及杂病，适宜用某个方剂时，随手拿来，没有不合规矩的。这叫做医生不固执于固定的方剂。现在谈论张仲景方剂的人，都说桂枝汤（Cinnamon Twig Decoction）治疗中风而不治疗伤寒，麻黄汤（Ephedra Decoction）治疗伤寒而不治疗中风。他们不知道张仲景的这些方剂主治什么样的症状，也不考察张仲景针对什么症状使用什么药物，只是在中风和伤寒这两种病症中进行比较，在青龙、白虎命名的基础上敷衍了事，把张仲景灵活的方剂和治法变成了死板的方剂和治法。
张仲景创立方剂，精妙而不杂乱。其中以六个方剂为主干，其他方剂在此基础上加减变化。凡是发汗的方剂，都以桂枝汤为基础；催吐的方剂，都以栀子豉汤（Gardenia and Fermented Soybean Decoction）为基础；攻下的方剂，都以承气汤（Gastro-Regulating Decoction）为基础；和解的方剂，都以柴胡汤（Bupleurum Decoction）为基础；清热的方剂，都以泻心汤（Drain the Epigastrium Decoction）为基础；温里的方剂，都以四逆汤（Four Reversal Decoction）为基础。笼统地数起来有一百一十三首方剂，那是没有仔细审察的缘故。
六经各有主治的方剂，而其他经也有互相通用的奥妙。比如桂枝汤和麻黄汤，是为太阳经营卫不和设立的，但阳明经病在营卫阶段的也使用它们。真武汤（Zhenwu Decoction）是为少阴经水气病设立的，但太阳经发汗后亡阳的也使用它。四逆汤是为太阴经下利清谷（腹泻排出未消化的食物）设立的，太阳经脉象反沉的也适宜使用。五苓散（Poria Powder）是为太阳经消渴、水逆（喝水即吐）设立的，阳明经饮水多的也适宜使用。猪苓汤（Polyporus Decoction）是为少阴经下利设立的，阳明经小便不利的也适宜使用。抵当汤（Diding Decoction）是为太阳经瘀血在里设立的，阳明经蓄血的也使用它。瓜蒂散（Melon Seed Powder）是为阳明经胸中痞硬设立的，少阴经温温欲吐的也使用它。符合这个症状，就使用这个方剂。方剂各有归属的经络，但应用可以不拘泥。这就是张仲景的法度。张仲景创立方剂，只有表里寒热虚实的不同，并没有伤寒、杂病、中风的分别。而且风寒有两首汤剂交替使用的妙处，表里有两首方剂更换应用的奇特之处。有的以全方取胜，有的通过加减奏效。前人论方不论症，所以反而认为张仲景的方剂难以使用。
桂枝汤是发汗剂中的上品。麻黄的药性，直达皮毛；生姜的药性，横散肌肉。所以桂枝辅助麻黄，就能打开玄府（汗孔）而驱逐卫分的邪气，让无汗的人出汗而病解，所以叫发汗。桂枝率领生姜，就能开泄腠理而驱除营分的邪气，让有汗的人继续出汗而病解，所以叫解肌。解肌，就是解除肌肉层面的邪气。邪气正在营分，为什么设立三纲理论的人，反而说麻黄主营、桂枝主卫呢？麻黄汤虽然没有说“解肌”，但肌肉的邪气并未尝不解；桂枝汤的“解肌”，正是为了发汗。要知道桂枝汤和麻黄汤是发汗深浅不同的方法，不能把发汗单独归给麻黄，也不能把解肌与发汗对立起来讨论。前人论方不论药，只把这两首方剂当作谈资，而搁置不用。
凡是风寒侵入人体，不在营卫之间，就在腠理之间。张仲景制定桂枝汤，是为了调和营卫；制定柴胡汤，是为了调和腠理。观察六经的症状，可知张仲景唯独提出桂枝证、柴胡证的称呼，可见这两首方剂责任重大，不可拘泥于某一经。只有太阳经统摄诸阳之气，六经的表证都归属于太阳，所以柴胡汤得以与桂枝汤在太阳经部相对待。桂枝汤本是为太阳经风寒设立的，凡是六经初感的外邪，尚未离开营卫的，都适宜使用。柴胡汤本是为少阳经半表半里设立的，凡是三阳经在表的外邪，还在腠理的，都适宜使用。张仲景的著作中最重视这两首方剂，所以专门为桂枝汤作注释，又为小柴胡汤（Minor Bupleurum Decoction）作注释。桂枝汤有疑似的症状，柴胡汤也有疑似的症状；桂枝汤有坏病（因误治而变坏的病证），柴胡汤也有坏病。桂枝证消失后，桂枝汤就不能再用了，但随症治疗的方法，仍然不离桂枝汤的加减；柴胡证消失后，柴胡汤就不能再用了，但设法救逆的方法，仍然不出柴胡汤的加减范围。
麻黄汤证，热邪完全在表；桂枝汤证的自汗、大青龙汤（Major Blue Dragon Decoction）证的烦躁，都兼有里热。张仲景在表剂中，就使用寒凉药物以清里热。自汗是烦躁的先兆，烦躁是躁动的征象。出汗则烦躁得以向外宣泄，所以不躁动，适宜用微寒酸苦的药物来调和；不出汗，则烦躁无法宣泄，所以躁动，适宜用大寒坚重的药物来清除。芍药和白石膏是治里的药，现在的人见到它们进入表剂中，不审察表中有里，因而产生疑惧，该用时不用，导致热邪并入阳明经，出现发黄、狂乱等症状，这是不能胜任大青龙汤的缘故。张仲景在太阳经中使用石膏来清胃火，这是预先保护阳明经的先着；加入姜、枣来培补中气，又是担心病邪转属太阴经。
小青龙汤和小柴胡汤，都是表里双解的方剂。小青龙汤重在里证，小柴胡汤重在表证。所以小青龙汤加减时，麻黄可以去掉；小柴胡汤加减时，柴胡独存。因为小青龙汤重在半里的水饮，小柴胡汤重在半表的热邪。
小青龙汤治疗伤寒未解的水气，所以用温剂发汗来驱散它；十枣汤（Ten Jujube Decoction）治疗中风已解的水气，所以用寒剂引导并竭尽它。这是寒水和风水不同的治疗方法。小青龙汤的水气，动荡而不固定；五苓散的水气，停留而不流动；十枣汤的水气，纵横不受约束；大陷胸汤（Major Thoracic-Suppressing Decoction）的水气，表现为痞硬坚满；真武汤的水气，表现为四肢沉重。水气为患各不相同，所以治疗方法各异。
林亿说：泻心汤原名理中黄连人参汤。大概泻心汤治疗痞证，正是运用理中法的地方。应当知道张仲景使用理中法时有寒热两种方法，一种用来扶助阳气，一种用来益养阴液。
邪气在营卫之间，只有发汗是它的出路，所以设立麻黄汤和桂枝汤。邪气在胸腹之间，只有催吐是它的出路，所以设立瓜蒂散和栀子豉汤。瓜蒂散主治胸中痞硬，治疗上焦病变；栀子豉汤主治腹部胀满而喘，治疗兼有中焦病变。就像麻黄汤主治皮肤，桂枝汤主治肌肉一样。瓜蒂散是峻猛之剂，犹如麻黄汤不可轻率使用；栀子豉汤是轻缓之剂，犹如桂枝汤可以反复使用而无妨。所以太阳经的表剂，多从桂枝汤加减；阳明经的表剂，多从栀子汤加减。阳明经使用栀子，犹如太阳经使用桂枝，既然可以用它来驱邪，就可以用它来救逆。现在的人只知道发汗是解表，而不知道催吐也是解表；知道催吐中能发散的道理，却不知道之所以要催吐的意义。所以在张仲景的大法中，只取发汗和攻下，而遗漏了催吐法。
少阳经为枢机，不全在里，也不全在表。张仲景的本意重在里，但柴胡汤所主的又在半表。所以必须见到半表的病情，才能从柴胡汤加减。如果邪气完全入里，那么柴胡汤就不胜任了。所以柴胡汤被称为解表的方剂。
小柴胡汤虽然治疗在半表，实际上是以调理三焦的气机为主，所以被称为枢机之剂。如胸满、胸中烦、心烦、心下悸、喜欢呕吐、咳嗽，这是上焦没有开发的气机；腹痛、胁下痞硬、不想饮食，这是中焦废弃了转运的职责；小便不利，这是下焦失去了决渎的功能。都是因为邪气与正气相搏结所致。用人参扶助三焦的正气，壮大其枢机功能。
四逆汤是太阴经的主方，但各经都可以互用。在太阴本经，是固本以驱逐邪气；用于少阴经，是温脾土以制约肾水；用于厥阴经，是调和脾土以生肝木；用于太阳经，是益火以扶持元阳。只有阳明经胃实、少阳经相火旺的情况，不适合使用。
少阴病四五日，腹痛，小便不利，下利不止，如果四肢沉重疼痛，这是下焦水郁，使用真武汤，这是引火归元的方法。如果大便脓血，这是下焦火郁，使用桃花汤（Peach Seed Decoction），这是升阳散火的方法。这是因为坎中（肾中）阳虚，不能把小便不利当作热证来治疗。
少阴病，二三日，心中烦，睡不着，病本在心，法当滋助离中（心中）的真水，顺应其势向下滋润，所以以黄连的苦寒为君药，以火泄热。四五日小便不利，下脓血，病本在肾，法当升发坎中（肾中）的少火，顺应其性向上炎上，所以以干姜的苦温为佐药，以发散之。这是伏明之火与升明之火治疗方法不同。
少阴病心烦欲睡，五六天想吐又吐不出来，自利且口渴，小便颜色白的，这是下焦虚寒，不能制火，适宜用真武汤，以温煦下焦的肾水。下利六七天，咳嗽而呕吐口渴，心烦失眠，这是上焦虚热，水精不能布散，适宜用猪苓汤以通调上焦的津液。
厥阴经下利，使用白头翁汤（Pulsatilla Decoction），是升阳散火，即火郁达之的意思；制作乌梅丸（Mume Pill）来救火，是曲直作酸的含义；佐以苦寒药物来调和阴液，主用温补药物来保存阳气，这是肝脏调理气机的方法。乌梅丸治疗伤寒的厥冷下利和久利，所以一半兼用温补；白头翁汤主治中风的热利和里急后重，所以专于凉散。
小柴胡汤是少阳经的主方，乌梅丸是厥阴经的主方。这两首方剂虽然不同，但寒温互用、攻补兼施的方法相合，是因为脏腑相连，经络相通，风木合气，共同主管相火。其中都使用人参，补益中气以固本逐邪，而其他药物都不相同，是因为阴阳位置不同。阳宜升散，所以主以柴胡；阴宜收降，所以主以乌梅。阳主热，所以重在寒凉；阴主寒，所以重用辛热。阳以动为用，所以用汤剂来荡涤；其症状变幻无常，所以柴胡汤有加法。阴以静为体，所以用丸剂来缓和；其症状有定局，所以乌梅丸没有加减法。手足厥逆的症状，有寒有热，有表有里。四逆散（Reversal of Extremities Powder）解除少阴经的里热；当归四逆汤（Angelica Decoction for Reversal of Extremities）疏散厥阴经的表寒；通脉四逆汤（Pulse-Recovering Four Reversal Decoction）挽救少阴经将亡的真阳；茯苓四逆汤（Poria and Four Reversal Decoction）留住太阳经欲脱的真阴。这四首方剂还有轻重浅深的区别。
按发表攻里，是抵御外邪的长技。表证都是因为风寒，如果表药用寒凉，那么表热未退，而中寒又起。所以表药必用桂枝，发表不远热。
然而这是针对太阳经表热而言的。如果是阳明经、少阳经的发热，则应当使用柴胡、黄芩、栀子、豆豉之类的方剂为主。里热都是因为郁热，下药不用苦寒，那么瘀热不除，邪气就没有出路。所以攻下剂必用大黄，攻里不远寒。然而这是针对阳明经胃热而言的。如果是恶寒痞硬、阳虚阴结的情况，又应当加上干姜、附子、巴豆之类的药物。
麻黄、桂枝，是太阳、阳明经表证的表药；瓜蒂、栀豉，是阳明经里证的表药；小柴胡汤，是少阳经半表半里的全方；太阴经的表药是桂枝汤；少阴经的表药是麻黄附子细辛汤（Ephedra, Aconite, and Asarum Decoction）；厥阴经的表药是当归四逆汤。六经使用表药，是为了给六经的风寒提供出路。
膀胱主水，是太阳经的里腑；十枣汤、五苓散，是太阳经水道之下的攻下药。胃腑主谷，是阳明经的里腑；三首承气汤，是阳明经谷道之下的攻下药。胆腑主气，是少阳经的里腑；大柴胡汤，是少阳经气分之下的攻下药。这三首是阳经之下药，是阳经实邪的出路。
大肠、小肠，都属于胃。胃家实，则大小肠都实了。如果分开来说，调胃承气汤（Stomach-Regulating Gastro-Regulating Decoction）是胃之下的攻下药，小承气汤（Minor Gastro-Regulating Decoction）是小肠之下的攻下药，大承气汤（Major Gastro-Regulating Decoction）是大肠之下的攻下药。戊为燥土，庚为燥金，所以加芒硝来润燥。
桂枝加大黄汤，是太阳经转属阳明经的攻下药；桂枝加芍药汤，是太阳经转属太阴经的攻下药。凡是下剂兼用表药的，是因为邪气尚未离开表。柴胡加芒硝汤，是少阳经转属阳明经的攻下药；大柴胡汤攻下少阳经无形的邪气；柴胡加芒硝汤攻下少阳经有形的邪气；桂枝加芍药汤攻下太阴经无形的邪气；三物白散（Three-Ingredient White Powder）攻下太阴经有形的邪气；四逆散攻下少阴、厥阴经无形的邪气；承气汤攻下各经有形的邪气。下剂轻的，只用气分药；下剂重的，兼用血分药。酸苦涌泄，下剂轻的，所以芍药、枳实为轻剂；咸苦涌泄，下剂重的，所以大黄、芒硝为重剂。
张仲景使用“攻下”二字，不专指大便。凡是给桂枝汤，想要攻其表，这是指发汗；表解了才可以攻之，这是指利水；有热属于脏的攻之，这是指清火；寒湿在里不可下，这是指利水，因为有热的原因；应当以法下之，这是指清火。
张仲景的下剂，只重在汤剂，所以说医生用丸药攻下，不是正确的治法。看陷胸汤、抵当汤两首丸剂，仍然是用水煮丸，再化为汤，连同药渣一起服用，那么势力比汤散更猛烈。应当知道张仲景的方剂以铢两分数计算的，不是治疗外感的方剂。丸药如梧桐子大，每次服用几十丸的，不是治疗外感的方法。张仲景制定方剂治疗疾病，在方后立下禁忌，使人接受其功效，不重蹈其弊端。比如用发表药，服一次出汗的，停止后面的服药；如果脉浮紧、发热出汗的，不可给予桂枝汤；如果脉微弱、出汗恶风的，不可服用大青龙汤；脉浮发热无汗、表证未解的，不可给予白虎汤；各种亡血虚弱的人，不可使用瓜蒂散；病人平时大便稀溏的，不可给予栀子豉汤；阳明病出汗多的，不可给予猪苓汤；外证未解，热度不潮的，不可给予承气汤；呕吐的人不可给予建中汤。看种种方剂禁忌，应当知道张仲景创立方剂时慎重的心意。
张仲景的加减中有深意。比如腹中痛的，少阳经加芍药，少阴经加附子，太阴经加人参。如果心下悸动的，少阴经加桂枝，少阳经加茯苓。如果口渴的，太阳经加栝蒌根、人参，太阴经加白术。张仲景在加减中区分阴阳表里如此细致。所以仔细审察张仲景的方剂，就知道随症立方奥妙；理解张仲景的加减法，就知道他用药取药的精妙。小青龙汤设有五种或然症，加减法内就备有五首方剂；小柴胡汤设有七种或然症，就有七首加减方。要知道张仲景有主治的方剂，如桂枝汤、麻黄汤等是；有方外之方，如桂枝汤加附子、加大黄是；有方内之方，如小青龙汤、真武汤等有加减是。张仲景的书，法外有法，方外有方，怎么能用三百九十七法和一百一十三首方剂来拘束呢？从前岐伯创立七方以治病，张仲景更进一步穷尽病的变幻，而尽其精微。比如发表攻里是驱逐外邪的大法，而发表攻里的方剂，各有大小，如小青龙汤、柴胡汤、陷胸汤、承气汤是。既然发表已有麻黄汤、桂枝汤，然而有里邪夹表而见的，治表不及里，不是正法。而里邪又有夹寒夹热的不同，所以制作小青龙汤，以治疗表热里寒；制作大青龙汤，以治疗表寒里热。这是表中更兼解里，必须像坏病那样先里后表、先表后里地再次计议。然而大小青龙汤，即是麻黄汤、桂枝汤的变化，足以解营卫之表，不足以驱腠理之邪。而且邪气留在腠理之间，半表半里的往来寒热虽然相同，但半表又有夹虚夹实的悬殊，因此制作小柴胡汤以防半里的虚，大柴胡汤以除半里的实。这是表中便见和里，岂像后人先攻后补、先补后攻的斟酌呢？攻里既有调胃承气汤，然而里邪在上焦的，有夹水夹痰的不同；在中焦的，有初硬后溏、燥屎定硬的区别，不是调胃承气汤一剂所能平复的。因此制作小陷胸汤以清胸膈之痰，大陷胸汤以下胸膈之水，小承气汤以试胃家的失气，大承气汤以攻肠胃的燥屎。方剂才有分寸，邪去而元气无伤，不至于有顾此遗彼、太过不及的祸患。按发表攻里的方剂，各有缓急的方法。比如麻黄汤、大承气汤，是汗下之急剂；桂枝汤，即发表的缓剂。其使用桂枝的各种方法，是缓汗中更有轻重。小承气汤，是下药的缓剂。说“少量给予，令其稍安”，说“微微调和胃气”，说“如果不转失气者令再给予”。调胃承气汤，则是下剂中尤为缓的。说“少量温服”，且不用气分药，更加甘草，是缓下中也有差别了。至于奇偶之法，各方已经具备。
桂枝二方，各半之偶；桂枝二麻黄一方，是奇。这是奇偶中各有浅深。服用桂枝汤后，须立刻喝稀粥，成为复方了。而更有取小柴胡汤服一升加芒硝的复方，这是复方中又分汗下二法了。至于白散使用复方更是奇异，不下利，进热粥一杯；下利不止，进冷粥一杯。是一杯粥又寓含热泻冷补的二法。
疾病有虚实相关、寒热夹杂的时候，有时药力所不能到达的地方，张仲景或用针或用灸来治疗。自从后世针药分为两途，哪里知道古人刺药相须的道理……
For all diseases, there are names and symptoms. There are mechanisms and clinical manifestations. For example, wind-stroke (Zhongfeng), cold damage (Shanghan), warm diseases (Wenbing), summerheat diseases (Shubing), dampness diseases (Shibing), etc., these are the names. External manifestations include headache, body heat, lower back pain; internal manifestations include wheezing and coughing, irritability and thirst, vomiting and diarrhea, distension and fullness. These are called symptoms. Among them, whether it is in the exterior or interior, with sweat or without sweat, pulse deep or floating, forceful or weak, this is the mechanism of the disease. At this time, aversion to cold, aversion to heat, chest and hypochondriac fullness and discomfort (Ku man), preference for vomiting, ability to eat or inability to eat, desire to sleep but unable to lie down, or drinking several liters of water, or rinsing the mouth but not wanting to swallow, these are all specific clinical manifestations of the disease. Those who formulate prescriptions based solely on the name are crude physicians; those who determine prescriptions based on symptoms are average physicians; those who examine the disease mechanism within the symptoms and observe the clinical manifestations are excellent physicians. Zhang Zhongjing formulated prescriptions without being constrained by the naming of diseases, only seeking accurate correspondence to symptoms. By mastering the mechanism and understanding the clinical manifestations, whenever wind-stroke, cold damage, or miscellaneous diseases are suitable for a certain prescription, one can pick it up at will, and none will fail to conform to the rules. This is what is meant by a physician not being rigidly attached to fixed prescriptions. Now, those who discuss Zhang Zhongjing's prescriptions say that Guizhi Tang (Cinnamon Twig Decoction) treats wind-stroke but not cold damage, and Mahuang Tang (Ephedra Decoction) treats cold damage but not wind-stroke. They do not know what symptoms these prescriptions of Zhang Zhongjing primarily treat, nor do they investigate what medications Zhang Zhongjing used for what symptoms. They merely compare wind-stroke and cold damage, making superficial remarks based on the naming of Qinglong (Blue Dragon) and Baihu (White Tiger), turning Zhang Zhongjing's flexible prescriptions and methods into rigid ones.
Zhang Zhongjing established prescriptions with precision and without clutter. He took six main prescriptions as the core, from which other prescriptions were derived through modifications. All diaphoretic (sweating-inducing) prescriptions are based on Guizhi Tang; all emetic prescriptions are based on Zhizi Chi Tang (Gardenia and Fermented Soybean Decoction); all purgative prescriptions are based on Chengqi Tang (Gastro-Regulating Decoction); all harmonizing prescriptions are based on Chaihu Tang (Bupleurum Decoction); all cooling prescriptions are based on Xiexin Tang (Drain the Epigastrium Decoction); all warming prescriptions are based on Sini Tang (Four Reversal Decoction). To count them indiscriminately as one hundred and thirteen prescriptions is to fail to examine them carefully.
Each of the Six Channels has its primary governing prescriptions, yet there is a subtlety in their mutual application across channels. For instance, Guizhi Tang and Mahuang Tang were established for disharmony of Ying (Nutrient) and Wei (Defensive) in the Taiyang Channel, yet they are also used for Yangming Channel diseases involving Ying and Wei. Zhenwu Tang (Zhenwu Decoction) was established for Water-Qi disorders in the Shaoyin Channel, yet it is also used for Yangming Channel post-diaphoresis collapse of Yang. Sini Tang was established for clear grain diarrhea in the Taiyin Channel, yet it is also suitable for Taiyang Channel cases with a reverse deep pulse. Wuling San (Poria Powder) was established for thirst and water-regurgitation in the Taiyang Channel, yet it is also suitable for Yangming Channel cases with excessive water intake. Zhuling Tang (Polyporus Decoction) was established for diarrhea in the Shaoyin Channel, yet it is also suitable for Yangming Channel cases with difficult urination. Diding Tang (Diding Decoction) was established for blood stasis in the interior in the Taiyang Channel, yet it is also used for blood accumulation in the Yangming Channel. Goudi San (Melon Seed Powder) was established for epigastric hardness in the Yangming Channel, yet it is also used for mild nausea in the Shaoyin Channel. Match the symptom, use the prescription. Each prescription belongs to a channel, but its application need not be confined. This is the method of Zhang Zhongjing. Zhang Zhongjing's prescriptions differ only in exterior/interior, cold/heat, deficiency/excess, without distinction between cold damage, miscellaneous diseases, or wind-stroke. Moreover, there is a妙 (wonder) in alternating two decoctions for wind-cold, and a奇 (uniqueness) in exchanging two prescriptions for exterior/interior. Some achieve success with the whole prescription, others through modifications. Predecessors discussed prescriptions without discussing symptoms, thus finding Zhang Zhongjing's prescriptions difficult to use.
Guizhi Tang is the premier diaphoretic prescription. The nature of Mahuang (Ephedra Herb) reaches directly to the skin and hair pores; the nature of Shengjiang (Fresh Ginger Rhizome) disperses horizontally through the muscles. Therefore, when Guizhi assists Mahuang, it opens the Xuanfu (pores) and expels pathogens in the Wei level, causing those without sweat to sweat and resolve. Hence it is called "inducing sweating." When Guizhi leads Shengjiang, it opens the Couli (interstices) and drives out pathogens in the Ying level, causing those with sweat to continue sweating and resolve. Hence it is called "releasing the muscle layer." Releasing the muscle layer means resolving pathogens in the muscles. Since the pathogen is in the Ying level, why do those establishing the Three Guidelines claim that Mahuang governs Ying and Guizhi governs Wei? Mahuang Tang does not mention "releasing the muscle layer," yet the muscle layer is invariably resolved; Guizhi Tang's "releasing the muscle layer" is precisely for inducing sweating. One must understand that Guizhi Tang and Mahuang Tang represent methods of inducing sweating at different depths. One cannot attribute sweating solely to Mahuang, nor oppose releasing the muscle layer against inducing sweating. Predecessors discussed prescriptions without discussing herbs, treating these two prescriptions merely as topics of conversation while leaving them unused.
When wind-cold invades the human body, it is either in the Ying-Wei or in the Couli. Zhang Zhongjing formulated Guizhi Tang to harmonize Ying and Wei, and Chaihu Tang to harmonize the Couli. Observing the symptoms of the Six Channels, one sees that Zhang Zhongjing uniquely named Guizhi Syndrome and Chaihu Syndrome, indicating that these two prescriptions bear heavy responsibility and should not be confined to a single channel. Only the Taiyang Channel commands the Qi of all Yang channels, and all exterior syndromes of the Six Channels belong to Taiyang. Thus, Chaihu Tang stands in contrast to Guizhi Tang in the Taiyang sector. Guizhi Tang was originally established for wind-cold in the Taiyang Channel. For any initial pathogenic invasion of the Six Channels that has not left the Ying-Wei, it is suitable. Chaihu Tang was originally established for the half-exterior/half-interior of the Shaoyang Channel. For any pathogenic invasion of the Three Yang channels still in the exterior/Couli, it is suitable. Zhang Zhongjing's work places the greatest emphasis on these two prescriptions, hence he provided annotations for both Guizhi Tang and Xiao Chaihu Tang (Minor Bupleurum Decoction). Guizhi Tang has ambiguous syndromes, and Chaihu Tang also has ambiguous syndromes; Guizhi Tang has complicated syndromes (Huabing), and Chaihu Tang also has complicated syndromes. Once the Guizhi syndrome resolves, Guizhi Tang is no longer applicable, but the method of treating according to symptoms still relies on modifications of Guizhi Tang. Once the Chaihu syndrome resolves, Chaihu Tang is no longer applicable, but the method of rescuing adverse conditions still relies on modifications of Chaihu Tang.
In Mahuang Tang syndrome, heat is entirely in the exterior. Spontaneous sweating in Guizhi Tang syndrome and restlessness in Da Qinglong Tang (Major Blue Dragon Decoction) syndrome both involve interior heat. Zhang Zhongjing uses cold-cooling herbs within exterior-releasing prescriptions to clear interior heat. Spontaneous sweating is a sign of irritability; irritability is a sign of agitation. Sweating allows irritability to vent outward, so there is no agitation; thus, slightly cold, sour, and bitter flavors are suitable to harmonize. Lack of sweating prevents irritability from venting, so there is agitation; thus, major cold, firm, and heavy substances are suitable to clear. Shaoyao (Peony Root) and Shigao (Gypsum Fibrosum) are interior herbs. Modern practitioners, seeing them in exterior prescriptions, fail to examine that the exterior contains interior aspects, leading to doubt and fear, resulting in non-use when use is indicated. Consequently, heat merges into the Yangming Channel, causing jaundice and madness, due to the inability to handle Da Qinglong Tang. Zhang Zhongjing uses Shigao in the Taiyang Channel to clear stomach fire, a preemptive move to protect the Yangming Channel. Adding Jiang (Ginger) and Zao (Jujube) cultivates Middle Qi, fearing transmission to the Taiyin Channel.
Xiao Qinglong Tang (Minor Blue Dragon Decoction) and Xiao Chaihu Tang are both exterior-interior dual-resolving prescriptions. Xiao Qinglong Tang focuses on interior symptoms, while Xiao Chaihu Tang focuses on exterior symptoms. Therefore, in modifying Xiao Qinglong Tang, Mahuang may be removed; in modifying Xiao Chaihu Tang, Chaihu remains alone. This is because Xiao Qinglong Tang focuses on water-fluids in the half-interior, while Xiao Chaihu Tang focuses on heat in the half-exterior.
Xiao Qinglong Tang treats water-fluids from unresolved cold damage, using warm diaphoretics to disperse them. Shizao Tang (Ten Jujube Decoction) treats water-fluids from resolved wind-stroke, using cold agents to guide and exhaust them. This is the differential treatment of cold-water and wind-water. The water in Xiao Qinglong Tang is dynamic and unsettled; the water in Wuling San is stagnant and immobile; the water in Shizao Tang is unrestrained; the water in Da Xianxiong Tang (Major Thoracic-Suppressing Decoction) presents as epigastric hardness and fullness; the water in Zhenwu Tang presents as heaviness in the four limbs. Water-pathogens vary, hence treatments differ.
Lin Yi stated: Xiexin Tang was originally named Lizhong Huanglian Renshen Tang. Essentially, treating epigastric fullness with Xiexin Tang is precisely applying the Lizhong method. One must know that Zhang Zhongjing used Lizhong methods with both cold and heat approaches: one to support Yang, one to benefit Yin.
When pathogens are between Ying and Wei, sweating is the only exit; thus, Mahuang Tang and Guizhi Tang were established. When pathogens are between the chest and abdomen, vomiting is the only exit; thus, Goudi San and Zhizi Chi Tang were established. Goudi San treats epigastric hardness, addressing the Upper Jiao; Zhizi Chi Tang treats abdominal fullness with wheezing, addressing the Middle Jiao. This is analogous to Mahuang Tang addressing the skin and Guizhi Tang addressing the muscles. Goudi San is a harsh agent, like Mahuang Tang, which should not be used lightly. Zhizi Chi Tang is a mild agent, like Guizhi Tang, which can be reused without harm. Therefore, Taiyang exterior prescriptions mostly modify from Guizhi Tang; Yangming exterior prescriptions mostly modify from Zhizi Tang. Using Zhizi in Yangming is like using Guizhi in Taiyang; just as it can drive out pathogens, it can also rescue adverse conditions. Modern people only know sweating as exterior resolution, not knowing that vomiting is also exterior resolution; they know vomiting can disperse, but not the rationale for vomiting. Thus, in Zhang Zhongjing's great method, they take sweating and purging but omit vomiting.
Shaoyang is the pivot, neither fully interior nor fully exterior. Zhang Zhongjing's original intent emphasized the interior, but Chaihu Tang governs the half-exterior. Therefore, one must see half-exterior clinical manifestations to modify Chaihu Tang. If pathogens enter completely interior, Chaihu Tang is no longer suitable. Hence Chaihu Tang is called an exterior-resolving prescription.
Although Xiao Chaihu Tang treats the half-exterior, it essentially regulates the Qi of the Three Jiao, hence it is called the Pivot Agent. Chest fullness, chest irritability, heart irritability, palpitations below the heart, preference for vomiting, and cough indicate a lack of developmental Qi in the Upper Jiao. Abdominal pain, hypochondriac hardness, and loss of appetite indicate the failure of transport functions in the Middle Jiao. Difficult urination indicates the loss of drainage function in the Lower Jiao. All result from the struggle between pathogenic factors and healthy Qi. Using Renshen (Ginseng Radix et Rhizoma) supports the healthy Qi of the Three Jiao and strengthens the pivot.
Sini Tang is the master prescription for the Taiyin Channel, yet it can be used mutually across channels. In the Taiyin Channel itself, it consolidates the root to expel pathogens. Used in the Shaoyin Channel, it warms Earth to control Water. Used in the Jueyin Channel, it harmonizes Earth to generate Wood. Used in the Taiyang Channel, it benefits Fire to support Primordial Yang. It is unsuitable only for Yangming Channel Stomach Excess and Shaoyang Channel Ministerial Fire.
In Shaoyin disease lasting four to five days, with abdominal pain, difficult urination, persistent diarrhea, if accompanied by heaviness and pain in the four limbs, it is Lower Jiao Water Depression. Use Zhenwu Tang; this is the method of guiding Fire back to its source. If there is pus and blood in stool, it is Lower Jiao Fire Depression. Use Taohua Tang (Peach Seed Decoction); this is the method of raising Yang and dissipating Fire. This is due to deficiency of Yang in Kan (Kidney); one must not treat difficult urination as Heat.
In Shaoyin disease lasting two to three days, with heart irritability and insomnia, the disease originates in the Heart. The method should nourish the True Water in Li (Heart), following its downward moistening tendency. Thus, Huanglian (Coptis Rhizoma) is used as the sovereign herb for its bitter cold to drain Fire. On days four to five, with difficult urination and pus/blood in stool, the disease originates in the Kidney. The method should raise the Lesser Fire in Kan (Kidney), following its upward flaming tendency. Thus, Ganjiang (Dried Ginger Rhizome) is used as the assistant herb for its bitter warmth to disperse. This demonstrates that Fu Ming Fire and Sheng Ming Fire require different treatments.
In Shaoyin disease with heart irritability and desire to sleep, after five to six days desiring to vomit but unable to, with spontaneous diarrhea and thirst, and white urine, this is Lower Jiao Deficiency-Cold failing to control Fire. Use Zhenwu Tang to warm the Kidney Water of the Lower Jiao. With diarrhea for six to seven days, cough, vomiting, thirst, heart irritability, and insomnia, this is Upper Jiao Deficiency-Heat with failure to distribute Water Essence. Use Zhuling Tang to unblock the fluids of the Upper Jiao.
For Jueyin Channel diarrhea, use Baitouweng Tang (Pulsatilla Decoction) to raise Yang and dissipate Fire, i.e., reaching out郁 (depressed) Fire. Prepare Wumei Wan (Mume Pill) to save Fire, embodying the principle of "curved and straight becoming sour." Assist with bitter-cold to harmonize Yin; primarily use warm-tonics to preserve Yang. This is the method of regulating Qi in the Liver. Wumei Wan treats cold-damage厥利 (cold extremities and diarrhea) and chronic diarrhea, hence half-warm-tonic. Baitouweng Tang treats wind-stroke heat-diarrhea and tenesmus, hence purely cool-dispersing.
Xiao Chaihu Tang is the master prescription for Shaoyang; Wumei Wan is the master prescription for Jueyin. Although different, their methods of interusing cold/warm and attacking/tonifying align because organs are connected, meridians intersect, Wind-Wood shares Qi, and they jointly govern Ministerial Fire. Both use Renshen to tonify Middle Qi, consolidate the root, and expel pathogens. Other herbs differ because Yin and Yang occupy different positions. Yang prefers ascending and dispersing, hence governed by Chaihu; Yin prefers gathering and descending, hence governed by Wumei. Yang governs Heat, hence emphasizes cold-cooling; Yin governs Cold, hence heavily uses pungent-warm. Yang uses movement, hence decoctions to sweep; symptoms are variable, hence Chaihu has modification methods. Yin uses stillness as substance, hence pills to缓 (slow); symptoms have a fixed pattern, hence Wumei has no modification methods. Cold extremities syndromes have cold/heat and exterior/interior distinctions. Sini San (Reversal of Extremities Powder) clears Shaoyin interior heat; Danggui Sini Tang (Angelica Decoction for Reversal of Extremities) disperses Jueyin exterior cold; Tongmai Sini Tang (Pulse-Recovering Four Reversal Decoction) salvages dying Shaoyin True Yang; Fuling Sini Tang (Poria and Four Reversal Decoction) retains departing Taiyang True Yin. These four prescriptions differ in severity and depth.
Expelling exterior and attacking interior are long skills in resisting pathogens. Exterior syndromes are caused by wind-cold. If exterior herbs are cold-cooling, exterior heat will not recede, and interior cold will arise. Thus, exterior herbs must use Guizhi; expelling exterior does not avoid heat.
However, this refers only to Taiyang exterior heat. For fever in Yangming and Shaoyang, one should use Chaihu, Huangqin (Scutellaria Root), Zhizi (Gardenia Fruit), and Chiyi (Fermented Soybean) primarily. Interior heat is due to depressed heat. If purgatives do not use bitter-cold, stasis-heat will not be removed, and pathogens will have no exit. Thus, purgatives must use Dahuang (Rhubarb Root and Rhizome); attacking interior does not avoid cold. However, this refers only to Yangming Stomach Heat. For aversion to cold, epigastric hardness, Yang deficiency with Yin binding, one should add Ganjiang, Fuzi (Aconite Lateralis Radix Praeparata), and Badou (Croton Seed).
Mahuang and Guizhi are exterior herbs for Taiyang and Yangming exterior. Goudi and Zhichi are exterior herbs for Yangming interior. Xiao Chaihu Tang is the complete prescription for Shaoyang half-exterior. Taiyin exterior herb is Guizhi Tang. Shaoyin exterior herb is Mahuang Fuxi Xixin Tang (Ephedra, Aconite, and Asarum Decoction). Jueyin exterior herb is Danggui Sini Tang. The use of exterior herbs for the Six Channels provides an exit for wind-cold in the Six Channels.
The Bladder governs Water and is the interior organ of Taiyang. Shizao Tang and Wuling San are purgatives for the Taiyang water pathway. The Stomach governs Grain and is the interior organ of Yangming. the three Chengqi prescriptions are purgatives for the Yangming grain pathway. The Gallbladder governs Qi and is the interior organ of Shaoyang. Da Chaihu Tang (Major Bupleurum Decoction) is a purgative for the Shaoyang Qi level. These three are purgatives for the Three Yang channels, providing an exit for excess pathogens in the Three Yang.
The Large Intestine and Small Intestine both belong to the Stomach. If Stomach Home Excess occurs, both intestines become excess. If divided: Tiaowei Chengqi Tang (Stomach-Regulating Gastro-Regulating Decoction) is the purgative for the Stomach; Xiaochengqi Tang (Minor Gastro-Regulating Decoction) is the purgative for the Small Intestine; Dachengqi Tang (Major Gastro-Regulating Decoction) is the purgative for the Large Intestine. Wu is Dry Earth, Geng is Dry Metal; thus, Mangxiao (Natrii Sulfas) is added to moisten.
Guizhi Jia Dahuang Tang (Guizhi Plus Rhubarb Decoction) is the purgative for Taiyang transferring to Yangming. Guizhi Jia Shaoyao Tang (Guizhi Plus Peony Decoction) is the purgative for Taiyang transferring to Taiyin. All purgatives combined with exterior herbs are because the pathogen has not left the exterior. Chaihu Jia Mangxiao Tang (Bupleurum Plus Natrii Sulfas Decoction) is the purgative for Shaoyang transferring to Yangming. Da Chaihu Tang attacks formless pathogens in Shaoyang; Chaihu Jia Mangxiao Tang attacks formed pathogens in Shaoyang. Guizhi Jia Shaoyao Tang attacks formless pathogens in Taiyin; Sanwu Baisan (Three-Ingredient White Powder) attacks formed pathogens in Taiyin. Sini San attacks formless pathogens in Shaoyin and Jueyin. Chengqi Tang attacks formed pathogens in various channels. Light purgatives use only Qi-level herbs; heavy purgatives combine Blood-level herbs. Sour-bitter induces vomiting and purging; light purgatives, hence Shaoyao and Zhishi (Immature Bitter Orange) are light agents. Salty-bitter induces vomiting and purging; heavy purgatives, hence Dahuang and Mangxiao are heavy agents.
Zhang Zhongjing's use of "attack and purge" does not refer exclusively to bowel movements. "Give Guizhi Tang to attack the exterior" refers to sweating. "Once the exterior is resolved, then attack" refers to promoting urination. "Attack heat belonging to the Zang organs" refers to clearing fire. "Cold-dampness in the interior cannot be purged" refers to promoting urination, due to heat. "Should be purged by method" refers to clearing fire.
Zhang Zhongjing's purgatives focus on decoctions, hence "physicians using pill-purgatives is not the correct treatment." Looking at Xiantong and Diding pills, they are still boiled in water, turned into decoctions, and taken with dregs, making their power more intense than decoctions or powders. One must know that Zhang Zhongjing's prescriptions measured in zhu and liang are not for external contractions. Pills the size of paulownia seeds, taken in dozens per dose, are not methods for treating external contractions. Zhang Zhongjing formulated prescriptions with post-prescription prohibitions to ensure efficacy and prevent abuse. For example, with exterior-expelling herbs, if one dose causes sweating, stop subsequent doses. If pulse is floating-tight, feverish, with sweating, do not give Guizhi Tang. If pulse is weak-micro, with sweating and aversion to wind, do not take Da Qinglong Tang. If pulse is floating, feverish, without sweat, exterior unresolved, do not give Baihu Tang (White Tiger Decoction). Various blood-loss and deficient persons should not use Goudi San. Patients with chronic loose stools should not take Zhizi Chi Tang. Yangming disease with excessive sweating should not take Zhuling Tang. Exterior unresolved, heat not tidal, do not give Chengqi Tang. Vomiting patients should not give Jianzhong Tang. Observing these prohibitions, one knows Zhang Zhongjing's cautious heart in formulating prescriptions.
Zhang Zhongjing's modifications contain profound meaning. For abdominal pain: Shaoyang adds Shaoyao; Shaoyin adds Fuzi; Taiyin adds Renshen. For palpitations below the heart: Shaoyin adds Guizhi; Shaoyang adds Fuling (Poria). For thirst: Taiyang adds Gualougen (Trichosanthes Root) and Renshen; Taiyin adds Baizhu (Atractylodes Macrocephala Rhizome). Zhang Zhongjing distinguishes Yin/Yang and Exterior/Interior in modifications thus. Carefully examining his prescriptions reveals the wonder of symptom-based formulation; understanding his modification methods reveals the precision of his herb selection. Xiao Qinglong Tang lists five optional symptoms, with five modified prescriptions prepared. Xiao Chaihu Tang lists seven optional symptoms, with seven modified prescriptions. One must know Zhang Zhongjing has master prescriptions (e.g., Guizhi, Mahuang), prescriptions outside prescriptions (e.g., Guizhi Tang plus Fuzi or Dahuang), and prescriptions inside prescriptions (e.g., modifications of Qinglong, Zhenwu). Zhang Zhongjing's book has methods beyond methods, prescriptions beyond prescriptions. How can it be confined to 397 methods and 113 prescriptions? Qi Bo created Seven Prescriptions to treat disease; Zhang Zhongjing further exhausted the variability of disease and its subtleties. Expelling exterior and attacking interior are major methods for expelling pathogens, but these prescriptions have sizes, such as Xiao Qinglong, Chaihu, Xiantong, Chengqi. Since there are Mahuang and Guizhi for exterior release, yet sometimes interior pathogens accompany exterior ones, treating exterior without interior is incorrect. Interior pathogens also vary by accompanying cold or heat. Thus, Xiao Qinglong Tang treats exterior heat-interior cold; Da Qinglong Tang treats exterior cold-interior heat. This is resolving interior within exterior, requiring calculation like complicated diseases (prioritizing interior/exterior sequentially). However, Da/Xiao Qinglong are variations of Mahuang/Guizhi, sufficient for Ying-Wei exterior but insufficient for Couli pathogens. Pathogens lingering in Couli share similar alternating chills/fever in half-exterior/half-interior, but vary greatly in deficiency/excess. Thus, Xiao Chaihu Tang prevents half-interior deficiency; Da Chaihu Tang removes half-interior excess. This shows harmonizing interior within exterior, unlike later predecessors' deliberation of attack-then-tonify or tonify-then-attack. Since there is Tiaowei Chengqi for interior attack, yet upper Jiao interior pathogens vary by accompanying water/phlegm, and middle Jiao varies by initial hardness/later looseness or definite dry feces, Tiaowei Chengqi alone cannot settle it. Thus, Xiao Xiantong Tang clears chest-phrenic phlegm; Da Xiantong Tang drains chest-phrenic water; Xiaochengqi Tang tests Stomach Qi failure; Dachengqi Tang attacks intestinal dry feces. Prescriptions have measure, pathogens leave without damaging Yuan Qi, avoiding neglecting one aspect for another or excess/deficiency. Regarding speed of exterior/expelling and interior/attacking prescriptions: Mahuang Tang and Dachengqi Tang are urgent sweating/purging agents. Guizhi Tang is a slow exterior agent; its various uses show degrees of slow sweating. Xiaochengqi Tang is a slow purgative; "give little to let it feel slightly better," "slightly harmonize Stomach Qi," "if no flatus, give again." Tiaowei Chengqi is the most slow purgative; "take little warm," "no Qi-level herbs, add Gancao," showing differences in slow purging. As for odd/even methods, they are already present in various prescriptions.
Two Guizhi prescriptions, each half, form an even pair; Guizhi Er Mahuang Yi is odd. There are depths within odd/even. After taking Guizhi Tang, drinking thin porridge makes it a compound prescription. Taking Xiao Chaihu Tang one sheng plus Mangxiao is another compound prescription, dividing sweating/purging within compounds. The use of Baisan with compounds is even more strange: if no diarrhea, drink one cup hot porridge; if diarrhea persists, drink one cup cold porridge. One cup of porridge contains two methods: hot-purge and cold-tonify.
Diseases have interrelated deficiency/excess and mixed cold/heat. Sometimes medicinal power cannot reach. Zhang Zhongjing uses acupuncture or moxibustion. Since later generations separated needles and medicines, how could they know the mutual necessity of ancient needle and medicine practices...