有友来予斋，见《知医必辨》，遍阅之，而以为明白晓畅，有益于人，力劝其再增十数
篇，
之?今予所作，不过为教训后人而设，意求清醒，明白若话，使子若孙一览而知而已!若以付
梓，则文多鄙俚，贻笑方家。此不可者一也。论中语多伤时，庸工所忌。设使若辈见予论，
而幡然改悔，则不独有济于世，而先有益于医；无如今之人，刚愎者多，虚心者少，徒增怨
毒而已!此不可者二也。且既付梓，难免流传他方，他方之医，未必尽善，而其习气未必如
吾乡，见吾书者，或以为异，谓吾处并无如此戕人者，要此何用?或且菲薄润色，医理不通
，予为此邦之人，亦复何光耶?此不可者三也。且今不通之辈，不讲医而讲术，呼朋引类，
互相标榜，杀人而不动心。我生之初，所见老辈，并无此恶习也。此嘉言先生所谓生民之扼
运，乃致医道中叠生鬼蜮耳!过此以往，或扼运已终，若辈将尽，后起者能真讲歧黄，不蹈
恶习，吾书又安所用之?此不可者四也。友曰∶听子之言，反复辨论，皆有至理，竟以不付
梓为是，然子之好辨殊难辞也。予笑应之曰∶予岂好辨哉，予不得已也!
时道光二十九年岁次己酉春正月再序于含饴堂之秋水轩时年七十有八
《内经》，即古三坟之书也。书之古，无有古于《内经》者，或疑有后人粉饰，未尝无
因。盖古书不独无今之刻本，且无笔无纸，不过韦编竹简刻划而成，其成书甚难，其传书必不多
。列国时，惟楚左史倚相得而读之，聪明颖悟，岂无他人?奈书不易得，故读者甚少也。其
时秦多良医，如和如缓，岂有未读《灵》、《素》者?则秦必有之，始皇焚书，而不焚医书
，故《内经》尚存，惟是代远年湮，必多残缺。韦编之绝，圣人之学《易》且然，而谓《内经
》之竹简，能久而完全乎?秦之后，楚汉分争，谁复能修理《内经》者?迨文景之世，汉已治
平，大儒辈出，必取《内经》修明之。今阅全书，颇有汉文气味，必非歧黄之原文。然如《
素问》所言五运六气，宏深奥妙，《灵枢》所言经络穴道，缕析条分，实秘笈之灵文，非神
灵其孰能知之?今学医者，不必读尽全书，如歧黄问答，尽可删去，只取其切要之句，牢牢
记之，临症引经施治，自然有靠。吾故曰∶ 庵之《类纂》、士材之《知要》，足以致用
也。
仲景先师作《伤寒论》，时在后汉，已有蒙恬之笔、蔡侯之纸，无庸刻竹，成书较易。
然其时蔡纸不多，尚有缣帛，三都赋成，洛阳纸贵，虽汉阳太守，成书一部，已属非易。不同今
日之刻本，但得一部，即化为千百部而无难也。故其书十六卷，至晋时已亡其《卒病》六卷
，至今莫之能见。然即观十卷中之一百十三方，攻补寒热，无所不备，已应用不穷。后世方
书，盈千累万，不能出其范围。学人能于仲景之方，精心探索，自然左右逢源，其他医书可
看不可看也。多集方书，始于唐王焘《外台秘要》。其方往往不合时宜，如茯苓饮一方，可
以古今通用者甚少，故曰可看不可看也。
医书之不能无疑者，莫如扁鹊之《难经》。扁鹊，渤海郡人也，姓秦氏，字越人，所居
地为卢，故又曰卢医。《史记》称其遇长桑君，授以禁方，饮上池水，视病尽见五脏症结，特以
诊脉为名。在晋视赵简子，在虢视虢太子，在齐视桓侯，皆一望而知。在赵贵妇人为带
下医，在周爱老人为耳目痹医，在秦爱小儿为小儿医。传记甚详，并未言有《难经》传世。
至仲景先师作《伤寒论》，惟本《内经》，亦未尝用《难经》。谓为扁鹊之书，殊可疑也。
且有可疑者，病机千变万化，而《难经》止八十一难，何能包括?且其一难至二十一难，皆
言脉；二十二难至二十九难，论经络流注、奇经之行及病之吉凶；三十难至四十三难，言荣卫
三焦脏腑肠胃；四十四、五难，言七冲门；四十六、七难，言老幼寤寐、气血盛衰，言人面
耐寒见阴阳之走会；四十八难至六十一难，言脉候病态，伤寒杂病之别，继以望闻问切而能
事毕矣；六十二难至八十一难，皆言脏腑荣 用针补泻之法。 然则其有益于方脉者，止六
十一难耳，何足以尽病情乎?且其论大率本乎《内经》，既有《内经》之详，何取《难经》
之
略?其中亦有与《内经》不合者，人将从《内经》乎?抑从《难经》乎?更可疑者，四十四难
论七冲门，会厌为吸门，胃为贲门，太仓下口为幽门，大小肠会为阑门，下极为魄门，而先
之以唇为飞门，齿为户门，此二门有何意味?似乎凑数而已!三十五难以小肠为赤肠，大肠为
白肠，胆为青肠，胃为黄肠，膀胱为黑肠，以五色为五肠，有非肠而以为肠者，似乎新奇，
而实无用。扁鹊神医，似不应有此凑数之文与无用之论。考汉晋六朝以前，无称越人着《难
经》者，至《隋唐书·经籍·艺文志》，始有《难经》，其真扁鹊之书耶?抑后人之假托耶?
好在其书无几，一览无余。学人究以《内经》为主，《难经》则参看而节取之，亦无不可也
。
学医之道，神圣之书，不可不读，后世之书，不必多看。唐许嗣宗医理甚精，而不肯着
书，
谓医者意也，可意会而不可言传。其好着书者，虽有切当，不过窃神圣之经而敷衍，其别出
心裁者，往往有偏僻之弊。如王叔和《脉经》，自以为仲景之徒矣，而后人之批驳者不少。
至今人所推尊者，以金元间刘、张、朱、李为四大家。以刘为首，其《原病式》果有发挥，
不可不看，然偏于用凉，不能辞也。张氏无书。朱则偏于养阴。李则偏于温补。东垣《脾胃
论》，实有至理。其补中益气汤，实开千古不传之秘，应用无穷。惟其论病，无论何症，皆
附会为脾胃之故，人之五脏六腑，岂无自病其经者?且尽如其论，丹溪养阴之书可废，乃今
人之阴亏者十有六七，补土克水，岂尽健脾所能治耶?且脾胃亦当有分，脾为阴土，宜于香
燥，胃为阳土，宜于清通，其性不同，治当有别，浑而言之，殊欠明晰。然则四大家之书，
尚难 尽信，何况下此者乎!四大家书，惟河间鲜有传其道者，殆用凉太过，难于获效乎!刘
完素医道虽高，未免有术，如自称尝梦二道士，饮似仙酒，醒时犹有酒味，从此医理精通。
此不过欲仿扁鹊遇长桑君故事，自炫以动人耳目。不然完素自病伤寒，八日不食，不能自治
，反需张洁古救之，何仙传能救人而不能自救耶?足见行道而兼行术矣。洁古作药注，草稿
始立，未及成书，言论往往见于《难经》，而其道则东垣传之。丹溪则有高弟戴元礼克传其
道，明太祖服其药。称为仁义人也。其道不用新奇，病无不治，足见师传之有法。惟后人假
其名，而着《证治要诀》，其书太简亦太浅，若辈只知假名获利，而不知反为名家之累也。
东垣传徒甚多，王海藏、罗谦甫其尤着者也。厥后薛立斋独宗之。薛氏着书最多，如《十六
种》，如《薛氏医案》，大旨以温补脾胃为主。张景岳最重薛氏，其偏于温补所自来也。吾
尝阅《薛氏医案》，其书不止盈尺，其症几于千万，一男子，一妇人，一小儿，一页可纪数
症，言之不详，徒令阅者繁多难记。此真薛氏所诊者耶?抑薛氏悬拟者耶?
自予见喻西昌《寓意草》，乃叹此真足称为医案，其议论详明透彻，真足益人神智。虽
王肯
堂《证治准绳》，论颇持正，医案不少，亦不能希冀喻氏。此予所以拜服西昌，而其他医案
置之不论也。若夫《冯氏锦囊》，乃三折肱于医道者，其书平正通达，先幼科，后方脉，
且
有至理，妇科、外科，无所不备，即痘科亦讲求精切，非今之幼科徒知用大黄凉药者，所能
望见。予尝救痘症数人，得力于《锦囊》也。喻氏而外，冯氏最善，其书不可不看。
他如士材之书《医宗必读》，虽名不及四大家，而其书颇有益于医道，亦不可不看。再
如《
东医宝鉴》，虽外夷之书，而内景、外形，本乎《内经》，足备参考。其症治分门别类，甚
属详明。如邪祟一门，有中国所不及载者。方虽繁杂，听人择取，适可临症备查，亦不可不
看。总之，医书汗牛充栋，何能尽阅?即吾家医书不少，初学亦难尽阅。然果能于吾诸论所
引之书，遍观而尽识，已胜于时下之空空，可以出而济世矣。
至书有徒美其名而不足济者，如生生子《赤水元珠》，似多元妙，其实人云亦云，平平
无奇
。其书盈尺，等于《锦囊》，以工夫看此，不如看冯氏矣。如《石室秘录》，冒陈眉公之名
，假托乩方，黄帝、岐伯、雷公、扁鹊、仲景、华佗，纷来踏至，日日到坛，有是理乎?其
方皆袭成方，而重其分量，一方用之数斤，以为奇异，以为仙方，有是理乎?虽其治法间有
可取，而其方何可用乎?孟子曰∶尽信书，则不如无书。此之谓矣。
是故予所立论，何能明医道之十一，但前人往往有欺人者，予一生不受人欺，不得不明
辨之，以示我后人，故特立篇名曰《知医必辨》。
有一位朋友来到我的书房，看到了《知医必辨》，通读之后，认为该书明白晓畅，对人有裨益，极力劝我再增加十几篇内容。
我回答说：我现在所写的这些，不过是用来教训后人的，意图在于追求清醒、语言像说话一样明白，让子孙后代一目了然就能知道罢了！如果拿去刻印出版，那么文字大多粗俗浅陋，会被内行专家嘲笑。这是不可行的第一点。书中言论多有时弊之伤，是庸医所忌讳的。假如那些庸人看了我的论述，能幡然悔悟，那不仅对社会有益，而且先对医学有益；可如今的人，刚愎自用的多，虚心求教的少，只会徒增怨恨和毒辣之心罢了！这是不可行的第二点。况且一旦刻印出版，难免流传到其他地方。其他地方的医生，未必都尽善尽美，而他们的习气也未必像我家乡这样。看到我的书的人，或许会认为怪异，说我们这里并没有如此害人的情况，要这书有什么用呢？或者还会轻视润色，导致医理不通，我作为这个地区的人，又有什么光荣呢？这是不可行的第三点。况且现在不通医道之辈，不讲医理而讲法术，呼朋引类，互相标榜，杀人却不动心。我出生之初，所见到的老一辈医生，并没有这种恶习。这就是嘉言先生所说的百姓命运多舛，致使医道中不断产生鬼蜮伎俩啊！过了这段时间，或许厄运已终，那些人将死绝，后来者能真正研习岐黄之术，不重蹈恶习，我的书又哪里用得着呢？这是不可行的第四点。朋友说：听你反复辩论，都有至理，最终决定不刻印出版是对的，然而你喜好辩论这一点很难推辞啊。我笑着回答他说：我难道喜好辩论吗，我是不得已啊！
时值道光二十九年（己酉年）春正月，在含饴堂的秋水轩再次作序，当时年龄七十八岁。
《内经》，就是古代“三坟”那样的书籍。书的古老，没有比《内经》更古老的了，有人怀疑其中有后人粉饰的痕迹，未尝没有原因。大概古书不仅没有现在的刻本，而且没有笔也没有纸，不过是韦编竹简刻划而成的，成书非常困难，传书必然不多。战国列国时期，只有楚国左史倚相得以阅读它，他聪明颖悟，难道没有其他人吗？无奈书不易得到，所以读者很少。那时秦国有很多良医，如秦和、秦缓，难道有没读过《灵枢》、《素问》的吗？那么秦国一定有这本书，秦始皇焚书，但没有焚烧医书，所以《内经》尚且存留，只是年代久远，必然多有残缺。韦编三断的故事连圣人在学习《易经》时都发生过，何况《内经》的竹简，怎么能长久保持完整呢？秦朝之后，楚汉分争，谁又能修理《内经》呢？等到汉文帝、汉景帝时代，汉朝已经治理太平，大儒辈出，必定取来《内经》加以修明。现在看全书，颇有汉代文章的气味，必定不是黄帝、岐黄的原文。然而如《素问》所言的五运六气，宏大深远奥妙，《灵枢》所言的经络穴道，条理分明，确实是秘笈中的灵文，如果不是神灵谁能知晓？现在学医的人，不必读尽全书，如黄帝与岐黄的问答，完全可以删去，只选取其中切要的语句，牢牢记住，临症时引用经典施治，自然有所依靠。所以我常说：吴谦的《医宗金鉴·类纂》、李士材的《知要》，足以达到实用目的。
张仲景先师撰写《伤寒论》时，处于后汉时期，已有蒙恬发明的笔、蔡伦改进的纸，无需刻竹，成书相对容易。然而当时蔡侯纸不多，还有缣帛，左思《三都赋》写成后，洛阳纸贵，即使是汉阳太守，写成一本书，也已经很不容易了。不像今天的刻本，只要得一部，就能化为千百部而不难。所以他的书十六卷，到了晋代已经亡失了《卒病论》六卷，至今没有人能见到。然而仅从剩下的十卷中的一百一十三首方剂来看，攻补寒热，无所不备，已经应用无穷无尽。后世的方书，成千上万，不能超出其范围。学医之人若能对仲景的方剂精心探索，自然左右逢源，其他的医书可以看也可以不看。大量汇集方书，始于唐代王焘的《外台秘要》。其中的方子往往不合时宜，如茯苓饮一方，可以古今通用的很少，所以说可以看也可以不看。
医书中不能不让人产生疑问的，莫过于扁鹊的《难经》。扁鹊是渤海郡人，姓秦，字越人，居住的地方叫卢，所以又叫卢医。《史记》称他遇到长桑君，传授给他禁方，饮用上池水，看病能看见五脏的症结，特别以诊脉著称。他在晋国见赵简子，在虢国见虢太子，在齐国见桓侯，都是一望而知病情。在赵国为贵妇人诊治带下病，在周国为老人诊治耳目痹症，在秦国喜爱小儿医术。传记记载得很详细，并未说有《难经》传世。直到张仲景先师作《伤寒论》，只依据《内经》，也未曾使用《难经》。说是扁鹊的书，特别可疑。而且有可疑之处，病机千变万化，而《难经》只有八十一难，怎么能包括得完？而且其一难至二十一难，都讲脉象；二十二难至二十九难，论述经络流注、奇经的运行及疾病的吉凶；三十难至四十三难，讲营卫、三焦、脏腑、肠胃；第四十四、五难，讲七冲门；第四十六、七难，讲老幼睡眠、气血盛衰，讲人脸耐寒见到阴阳走向会合；第四十八难至六十一难，讲脉候病态，伤寒杂病的区别，接着以望闻问切而能力完备；第六十二难至八十一难，都讲脏腑营卫，用针补泻的方法。既然如此，它对方脉有益的，只有前六十一难而已，怎么足以穷尽病情呢？况且它的论述大体依据《内经》，既然有了《内经》的详细，何必取《难经》的简略？其中也有与《内经》不合的地方，人们是遵从《内经》呢，还是遵从《难经》呢？更可疑的是，第四十四难论七冲门，会厌为吸门，胃为贲门，太仓下口为幽门，大小肠会为阑门，下极为魄门，而在前面加上唇为飞门，齿为户门，这两个门有什么意味？似乎是凑数而已！第三十五难以小肠为赤肠，大肠为白肠，胆为青肠，胃为黄肠，膀胱为黑肠，以五色为五肠，有不是肠而当作肠的，似乎新奇，而实际上无用。扁鹊是神医，似乎不应该有这样的凑数之文和无用之论。考察汉晋六朝以前，没有称越人著《难经》的，直到《隋唐书·经籍·艺文志》，才开始有《难经》，这真是扁鹊的书吗？还是后人的假托呢？好在书不多，一览无余。学人终究以《内经》为主，《难经》则参看而节取之，也没什么不可以的。
学医之道，神圣的经典，不可不读，后世的书籍，不必多看。唐代许嗣宗医理精深，但不肯著书，说医者意也，可以意会而不可言传。那些喜欢著书的人，虽然有恰当之处，不过是窃取神圣的经典而敷衍，其别出心裁的，往往有偏颇的弊端。如王叔和的《脉经》，自以为他是仲景的徒弟，但后世批驳他的人不少。至今人们推崇的，以金元间的刘、张、朱、李为四大家。以刘完素为首，他的《原病式》果真有发挥，不可不看，然而偏重于用凉药，是不能推辞的。张元素没有留下著作。朱震亨偏重于养阴。李东垣偏重于温补。东垣的《脾胃论》，确实有至理。他的补中益气汤，确实开启了千古不传的奥秘，应用无穷。只是他论病，无论什么症状，都附会为脾胃的缘故，人的五脏六腑，难道没有自己经脉生病的吗？而且完全按照他的论述，丹溪的养阴之书就可以废弃了，可是如今阴亏的人十有六七，补土克水，难道都是健脾所能治疗的吗？况且脾胃也应当区分，脾为阴土，适宜香燥，胃为阳土，适宜清通，它们的性质不同，治疗应当有别，笼统地说，很不明晰。那么四大家的书，还难以完全相信，何况低于他们的人呢！四大家的书，只有河间（刘完素）鲜少有人传承其道，大概是用药太凉，难以获得疗效吧！刘完素医道虽然高，未免有些术法，如自称曾经梦见两个道士，喝像仙酒一样的东西，醒来时还有酒味，从此医理精通。这不过是想模仿扁鹊遇长桑君的故事，自我炫耀以动人耳目。不然完素自己得了伤寒，八天不吃饭，不能自治，反而需要张洁古救他，什么仙传能救人而不能自救呢？足见他行道而兼行术。张洁古作药注，草稿刚立，未及成书，言论往往见于《难经》，而他的道则是李东垣传承的。朱丹溪则有高徒戴元礼很好地传承其道，明太祖服用他的药，称为仁义人。他的道不用新奇，病无不治，足见师传有法。只是后人假借他的名字，而著《证治要诀》，那本书太简单也太浅薄，那些人只知道假名获利，却不知道反而成为名家的累赘。
李东垣传徒很多，王海藏、罗谦甫是最著名的。其后薛立斋独自尊崇他。薛氏著书最多，如《十六种》，如《薛氏医案》，大旨以温补脾胃为主。张景岳最重视薛氏，他偏于温补由此而来。我曾经阅读《薛氏医案》，那书不止一尺厚，病症几乎千万，一个男子，一个妇人，一个小儿，一页可以记录几个病症，说得详细，徒令读者繁多难记。这真是薛氏所诊断的吗？还是薛氏悬空推测的呢？
自从我见到喻西昌的《寓意草》，才感叹这真足以称为医案，其议论详明透彻，真足以益人神智。虽然王肯堂的《证治准绳》，论点颇为持正，医案不少，也不能期望达到喻氏的水平。这就是我拜服西昌，而其他医案置之不论的原因。至于《冯氏锦囊》，是三次折断肱骨（比喻经验丰富）于医道的人，他的书平正通达，先讲儿科，后讲方脉，且有至理，妇科、外科，无所不备，就连痘科也讲求精切，不是如今儿科只知道用大黄凉药的人所能望见的。我曾经救治几个痘症患者，得力于《锦囊》。除了喻氏之外，冯氏最擅长，他的书不可不看。
其他的如李士材的书《医宗必读》，虽然名声不及四大家，但他的书颇有益于医道，也不可不看。再如《东医宝鉴》，虽然是外国书，而内景、外形，本乎《内经》，足备参考。其症治分门别类，甚属详明。如邪祟一门，有中国所不及记载的。方子虽然繁杂，听人择取，适合临症备查，也不可不看。总之，医书汗牛充栋，怎么能全部阅读？即使我家医书不少，初学者也难以全部阅读。然而如果能对我诸论中所引用的书，遍观而尽识，已经胜过时下那些空空如也的人，可以出来济世了。
至于书有徒美其名而不足济世的，如生生子的《赤水元珠》，似乎多元妙，其实人云亦云，平平无奇。那书一尺厚，等于《锦囊》，花工夫看这个，不如看冯氏的了。如《石室秘录》，冒用陈眉公的名字，假托乩方，黄帝、岐伯、雷公、扁鹊、仲景、华佗，纷至沓来，日日到坛，有这种道理吗？其中的方子都袭用成方，而加重分量，一方用几斤，以为奇异，以为仙方，有这种道理吗？虽然其治法间或有可取之处，但其方怎么用呢？孟子说：尽信书，则不如无书。说的就是这个意思。
所以我所立的论，怎么能阐明医道的十分之一，但前人往往有欺人的地方，我一生不受欺，不得不明辨之，以示我后人，所以特立篇名曰《知医必辨》。
A friend came to my study, saw *Zhi Bi Bi Bian* (Knowing Medicine Must Be Distinguished), read it through, and found it clear and fluent, beneficial to people. He strongly urged me to add ten or more additional chapters.
I replied: What I have written now is merely intended to instruct future generations, aiming for clarity and plain language so that descendants can understand it at a glance! If I were to have it printed and published, the text would be too vulgar and crude, inviting ridicule from experts. This is the first reason why it cannot be done. The discussions in the book often offend contemporary practices, which are taboo for mediocre practitioners. Suppose those individuals see my arguments and repent; then not only would it benefit society, but it would first benefit medicine. However, nowadays, most people are stubborn and conceited, while few are humble and open-minded; it would only increase resentment and malice! This is the second reason why it cannot be done. Moreover, once printed, it will inevitably spread to other regions. Doctors in other places may not be perfect, and their habits may differ from ours. Those who see my book might find it strange, saying there are no such harmful practices in our area, asking what use this book is? Or they might belittle and polish it, leading to incomprehensible medical principles. As a person of this region, what glory would I gain? This is the third reason why it cannot be done. Furthermore, nowadays, those ignorant of medicine do not discuss medical theory but focus on tricks, calling friends and recruiting followers, praising each other, killing people without remorse. When I was young, the elders I saw did not have such bad habits. This is what Mr. Jiayan (Yu Chang) called the unfortunate fate of the people, causing ghostly tricks to repeatedly emerge in the medical way! After this period, perhaps the bad luck will end, those people will die out, and later generations will truly study the Yellow Emperor and Qibo (Huangdi and Qibo, ancient mythical emperors and physicians regarded as founders of Chinese medicine), avoiding bad habits. In that case, where would my book be needed? This is the fourth reason why it cannot be done. The friend said: Listening to your repeated arguments, all contain profound truths. It is right to decide not to print it, but your fondness for debate is hard to deny. I smiled and replied: Do I enjoy debating? I am compelled to do so!
Preface again in the first month of spring, in the year Jiyu (1849) of the Daoguang era, at Qiushui Xuan in Hanyi Hall, aged seventy-eight.
*Neijing* (The Inner Canon) is a book from the ancient "Sanfen" (Three Ancient Treatises). No book is older than *Neijing*. Some suspect it has been embellished by later generations, which is not without cause. Ancient books not only lacked modern printing blocks but also had no pens or paper; they were merely carved onto bamboo slips bound with leather cords. Thus, compiling them was very difficult, and transmitting them was rare. During the Warring States period, only Yi Xiang, the Left Historian of Chu, could read them. Was he the only one intelligent enough? No, but since the books were hard to obtain, few readers existed. At that time, Qin had many good doctors, such as He and Huan. Could there have been none who read *Lingshu* (Spiritual Pivot) and *Suwen* (Basic Questions)? Qin must have possessed them. When Qin Shi Huang burned books, he did not burn medical texts, so *Neijing* survived. However, due to the passage of time, it must have suffered much damage. Even the Sage broke the binding cords while studying *Yijing* (Book of Changes); how could the bamboo slips of *Neijing* remain intact over centuries? After Qin, during the Chu-Han contention, who repaired *Neijing*? By the reigns of Emperors Wen and Jing of Han, when peace prevailed, great scholars emerged and likely revised *Neijing*. Reading the complete work today, it bears the flavor of Han dynasty literature, certainly not the original words of Huangdi and Qibo. Yet, the Five Movements and Six Qi (Wuyun Liuqi, a theory of cosmic cycles affecting health) described in *Suwen* are profound and mysterious, and the meridians and acupoints detailed in *Lingshu* are meticulously analyzed. These are indeed spiritual texts of secret manuals; only gods could know them. Modern students of medicine need not read the entire book. The dialogues between Huangdi and Qibo can be deleted; one should only memorize the essential sentences. When treating patients, citing classics provides a solid foundation. Therefore, I say: Wu Qian’s *Leizuan* (Classified Compilation) and Li Shicai’s *Zhiyao* (Essentials) are sufficient for practical application.
Master Zhang Zhongjing wrote *Shanghan Lun* (Treatise on Cold Damage) during the Later Han Dynasty. By then, Meng Tian’s pen and Cai Hou’s paper existed, making compilation easier than carving bamboo. However, Cai paper was scarce, and silk was still used. After Zuo Si’s *San Du Fu* became popular, paper in Luoyang became expensive. Even for a governor like Han Yang, producing a book was not easy. Unlike modern printing, where one copy yields thousands, his sixteen-volume work lost six volumes of *Zhubing Lun* by the Jin Dynasty, which remain unseen today. Nevertheless, observing the 113 formulas in the remaining ten volumes, covering attacking, tonifying, cooling, and warming, applications are inexhaustible. Later formula books, numbering in the thousands, cannot exceed its scope. If students carefully explore Zhongjing’s formulas, they will find resources everywhere, rendering other medical books optional. Collecting formulas extensively began with Wang Tao’s *Waitai Miyao* (Secret Essentials of the Outer Court) in the Tang Dynasty. Many formulas therein are outdated; for instance, *Fuling Yin* (Poria Decoction) is rarely applicable across eras. Hence, these books are "readable but not necessarily usable."
Among medical books, the one raising the most doubts is Bian Que’s *Nanjing* (Classic of Difficult Issues). Bian Que, courtesy name Yueren, was from Bohai Commandery, surnamed Qin, residing in Lu, hence called Doctor Lu. *Records of the Grand Historian* states he met Master Changsang, received secret prescriptions, drank water from above the pool, and could see internal organ pathologies, famous especially for pulse diagnosis. He treated Duke Jian of Zhao, the Crown Prince of Guo, and Duke Huan of Qi, diagnosing instantly. In Zhao, he treated gynecological disorders; in Zhou, ear, nose, and throat obstructions in the elderly; in Qin, pediatrics. Biographies are detailed but mention no *Nanjing*. When Zhang Zhongjing wrote *Shanghan Lun*, he relied solely on *Neijing*, never using *Nanjing*. Attributing it to Bian Que is highly suspicious. Moreover, disease mechanisms are myriad, yet *Nanjing* contains only eighty-one difficulties; how can it encompass everything? Chapters 1-21 discuss pulses; 22-29 discuss meridians, extraordinary vessels, and prognosis; 30-43 discuss Ying-Wei, Sanjiao, zang-fu, and bowels; 44-45 discuss the Seven Gates; 46-47 discuss sleep, qi-blood decline, and facial cold resistance; 48-61 discuss pulse signs, cold damage vs. miscellaneous diseases, and four diagnostic methods; 62-81 discuss zang-fu, Ying-Wei, and acupuncture tonification/sedation. Thus, only up to Chapter 61 relates to prescription and pulse. How can this exhaust pathology? Its theories largely derive from *Neijing*; if *Neijing* is detailed, why need *Nanjing*’s brevity? Where they conflict, which should one follow? More suspiciously, Chapter 44 on the Seven Gates lists lips as Flying Gate, teeth as Household Gate, epiglottis as Suction Gate, stomach entrance as Receiving Gate, lower stomach outlet as幽门 (Yumen/Hiding Gate), large/small intestine junction as Lan Gate, and anus as Po Gate. Why add the first two seemingly to fill space? Chapter 35 calls small intestine Red Intestine, large intestine White Intestine, gallbladder Green Intestine, stomach Yellow Intestine, bladder Black Intestine. This seems novel but useless. A divine doctor like Bian Que would not write such filler or useless theories. Before Han, Jin, and Six Dynasties, no one attributed *Nanjing* to Yueren. It first appears in *Sui-Tang Book of Classics and Arts*. Is it truly Bian Que’s or a later forgery? Fortunately, the book is short. Students should prioritize *Neijing* and consult *Nanjing* selectively.
In learning medicine, sacred classics must be read, but later books need not be studied extensively. Xu Sizong of Tang had profound medical knowledge but refused to write, saying "medicine is intention," understood intuitively but not verbally. Those who love writing, even if accurate, merely elaborate on sacred classics; those innovating often have biases. For example, Wang Shuhe’s *Maijing* (Pulse Classic), claiming to be Zhongjing’s disciple, faced much criticism. Today, the Four Great Masters of Jin-Yuan—Liu, Zhang, Zhu, Li—are revered. Liu Wansu’s *Yuanbing Shi* (Original Formulas for Disease Patterns) is insightful and essential, though biased toward cooling herbs. Zhang Congzheng left no works. Zhu Danxi emphasized nourishing yin. Li Dongyuan emphasized warming and tonifying. Li’s *Piwei Lun* (Treatise on Spleen and Stomach) contains profound truth. His *Buzhong Yiqi Tang* (Tonify the Middle and Augment the Qi Decoction) reveals an ancient secret with infinite applications. However, he attributed all diseases to spleen-stomach issues, ignoring that organs can suffer independently. If we follow him, Danxi’s yin-nourishing books would be obsolete. Yet, today, 60-70% suffer yin deficiency. Strengthening earth to control water is not always solved by strengthening spleen. Spleen (yin earth) prefers aromatic-dryness; stomach (yang earth) prefers clearing-unblocking. Their natures differ, requiring distinct treatments. Generalizing them lacks clarity. Thus, even the Four Masters’ books are not fully trustworthy, let alone inferior ones. Only Liu Wansu’s lineage is rarely transmitted, likely because excessive cooling fails to produce effects. Liu claimed dreams of immortals giving him wine, enhancing his wisdom. This mimics Bian Que’s story to impress others. Otherwise, Liu himself suffered cold damage for eight days without eating, unable to heal himself, needing Zhang Jiegu’s help. How could immortal transmission save others but not himself? This shows he combined practice with trickery. Zhang Jiegu’s herbal notes were unfinished; his ideas appeared in *Nanjing*, transmitted to Li Dongyuan. Zhu Danxi’s disciple Dai Yuanli inherited his way well; Ming Taizu respected him. His methods were unpretentious and effective, proving proper transmission. Later forgers used his name for *Zhengzhi Yaojue* (Essential Guidelines for Diagnosis and Treatment), which is too simple and shallow. They sought profit, disgracing the master.
Li Dongyuan taught many, notably Wang Haizang and Luo Qianfu. Later, Xue Lizhai followed him exclusively. Xue wrote extensively, including *Xue Shi Yi An* (Case Records of Dr. Xue), focusing on warming-tonifying spleen-stomach. Zhang Jingyue valued Xue greatly, leading to his own bias toward warming-tonification. I read *Xue Shi Yi An*; it is thick, listing countless cases per page for men, women, children. Details are sparse, making memory difficult. Were these real diagnoses or hypothetical scenarios?
Seeing Yu Xichang’s *Yuyi Cao* (Grass of Meaningful Intentions), I sighed: this truly qualifies as a case record. Its discussions are detailed and penetrating, benefiting the mind. Although Wang Kentang’s *Zhengzhi Zhunsheng* (Standard Guidelines for Diagnosis and Treatment) is orthodox and rich in cases, it cannot match Yu. This is why I admire Xichang and ignore other case records. *Feng Shi Jin Nang* (Golden Pouch of the Feng Family) represents extensive experience. Its content is balanced and accessible, covering pediatrics before internal medicine, with sound principles for gynecology, surgery, and smallpox. It is precise, unlike modern pediatricians who blindly use rhubarb and cooling herbs. I saved several smallpox patients using *Jin Nang*. Besides Yu, Feng is excellent; his book is essential.
Li Shicai’s *Yizong Bixdu* (Must-Read Books for Medical Practitioners), though less famous than the Four Masters, is beneficial and worth reading. *Dongui Bogam* (Eastern Medical Treasure Mirror), though foreign, bases internal/external structures on *Neijing*, providing valuable reference. Its categorization is detailed. It includes entries on evil spirits absent in Chinese texts. Though formulas are complex, they allow selection for clinical reference. It is indispensable. Medical books are numerous; no one can read them all. Even in my family, beginners cannot read them all. But if one thoroughly studies the books cited in my discussions, surpassing empty-headed contemporaries, one can practice and help the world.
Some books are famous but useless, such as *Chishui Yuanzhu* (Pearl of Chishui) by Shengshengzi. It claims profundity but is derivative and mediocre. Its thickness equals *Jin Nang*, but studying it is inferior to studying Feng. *Shishi Milu* (Secret Records of the Stone Chamber) falsely attributes itself to Chen Meigong and uses spirit-writing. Huangdi, Qibo, Leigong, Bian Que, Zhongjing, Hua Tuo supposedly visit daily. Absurd! Formulas are copied but dosages increased to pounds, claimed as miraculous or immortal. Unreasonable! Though some treatments are acceptable, the formulas are unusable. Mencius said: "To believe everything in books is better than having no books." This applies here.
Thus, my arguments clarify only a fraction of medical truth. Since predecessors often deceived, and I refuse to be deceived, I must distinguish clearly for future generations. Hence, I titled this section *Zhi Bi Bi Bian* (Knowing Medicine Must Be Distinguished).