《金匮要略》曰∶千般 难，不越三条∶（ ，丑刃切，音趁。）一者经络受邪入脏腑，为内所因也；二者四
肢九窍，血脉相搏，壅塞不通，为外皮肤所中也；
三者房室金刃虫兽所伤。以此详之，病由都尽。（《金匮》）
二条，皆重外因，以房室、服食为内因。）宋成无己曰∶病有三因∶
一者外因于天，二者内因于人，三者不内外因。外因于天者，风寒暑湿之六淫也；内因于人者，喜怒忧恐
之七情，及饮食、房劳也；不内外因者，金刃、跌扑、虫兽、笞杖之所伤也。人之百病，不外此三者。夫伤
寒，外因也，而《伤寒》经旨，风寒暑湿之六气，咸所具载矣。其间分析表里、阴阳、寒热、气血、邪正
虚实，（内外百病，不出此十二字。）靡不备悉。明乎伤寒之道，千般病难，不出于范围焉。故医学入门，当从伤寒
始，先难其所难，而后易其所易。盖外因之病暴而危，内因之病徐而持。（中风、疟、痢、痿、痹、疝、厥、头腹诸痛，
多系外因。）故治外感者，可以活人，可以死人；治内伤者，或少有失误，未即为害。是以能医内伤，而不谙
治伤寒者，未可医名也；能医伤寒，而不谙治内伤者，未之有也。
月三、六、九晨，集及门，说《内经》及《伤寒论》，讲毕，谓诸生曰∶时俗相沿云，行医全凭时
运，予以为不然。诸生来学，当苦志读书，细心参究，庶可免庸医之责，若凭时运，则何业不可为，而
习此苦难之事！设使杀一不辜，而救百人，其功不能赎罪。盖救人乃医家分内事，况多有病之轻者，有病
之自能愈者，或病虽剧而可救者。越人曰∶仆不能生人耳，不起之病，仆能起之，是非必死之病，而医能
活之。若使病者不死于病，而反死于医，又何异于梃刃，是以救人之功小，误伤之罪大。试观栽杏叟，尚
误投药饵，伤及母子二命，况平人乎？然此亦警世之事也。古今名流，皆生前根气丰浓，若再加培植，即
可名登仙籍，惜乎不能何也？既已名擅当时，焉肯虚心下士，况一人之精神有限，或忙中有错，即误用其
药，亦不自知其非，病家延请惟艰，幸而至之，焉敢论其是非，即服药有误，反归于死者之命。是以运之
小者其过小，运之大者其过大。诸生能鉴予言，潜心好学，将来运之小者可大，运之大者可无过矣。
开之曰∶历观古今医家，有子孙显达者，有子孙式微者，大有霄壤之分，若不图名、不贪利，虚衷受益，存
心活人，有不永昌厥后者乎！
又曰∶古称医士为山中宰相，谓能燮理阴阳，调和气味，操生杀之柄耳！《记》云∶医不三代，不服其药。
许学士曰∶谓能读三代之书。予以为世代相传，又能读书好学，犹簪缨世胄，士之子而恒为士也。若
仅守遗方，以为世传，何异按图索骥。夫天有四时之气，地有五方之异，人之百病，变幻多端，即如伤寒
一证，有三百八十九法，可胶执遗方，能通变时疾乎？赵括徒读父书，尚至丧师败绩，况无遗书可读
耶！守祖父之业而不好学人，可方草庐诸葛乎？伊芳川先生曰∶医不读书，纵成仓、扁，终为技术之流，非
士君子也。卢不远先生曰∶当三复斯语。（及门者多系 世医子弟，故复言此以戒之。）
《金匮要略》说：千种万般的疾病，不离三条原因：（“疢”，音chèn，意为病。）一是经络受邪气侵入脏腑，属于内部的原因；二是四肢和九窍，血脉相互搏结，壅塞不通，属于外部皮肤受到的侵害；三是房事过度、金属利器损伤以及虫兽咬伤。由此详细分析，疾病的成因就完全清楚了。（出自《金匮要略》）第二条主要强调外因，而将房事、饮食不当视为内因。）宋代成无己说：病因有三类：一是外因于天，二是内因于人，三是不内外因。外因于天的，是指风、寒、暑、湿等六淫邪气；内因于人的，是指喜、怒、忧、恐等七情，以及饮食不节、房劳过度；不内外因的，是指金属利器、跌打损伤、虫兽咬伤、鞭打刑具所造成的伤害。人的各种疾病，都不出这三类。所谓伤寒，属于外因，但《伤寒论》这部经典，已经详尽记载了风、寒、暑、湿等六气。其中对表里、阴阳、寒热、气血、邪正、虚实的辨析，（内外百病，不出这十二个字。）无不完备。明白了伤寒的道理，千种万种的疾病，就不超出这个范围了。所以医学入门，应当从伤寒开始，先攻克难点，然后再处理容易的部分。大概外因引起的病发作急骤且危险，内因引起的病发展缓慢且持久。（中风、疟疾、痢疾、痿证、痹证、疝气、厥证、头腹各部位疼痛，多与外因有关。）所以治疗外感病的医生，可以救人，也可以杀人；治疗内伤病的医生，即使偶尔有失误，也不会立即造成危害。因此，能治内伤却不精通伤寒治疗的，不能称为名医；能治伤寒却不精通内伤治疗的，这种情况是没有的。
每月初三、初六、初九的早晨，召集门徒弟子，讲解《黄帝内经》和《伤寒论》，讲完后，对众学生说：世俗相沿袭的说法是，行医全凭时运，我认为不是这样。你们来学习医术，应当刻苦立志读书，细心探究研究，才可以避免庸医的责任。如果凭借时运，那么什么职业不可以做，何必习练这件苦难的事情！假使误杀一个无辜的人，却救了上百人，他的功劳也不能赎清罪过。拯救生命本是医生的本分，况且有很多病情轻浅的，有病自己能痊愈的，或者病情虽然严重但可以救治的。扁鹊（越人）说：我不能让人起死回生，但对于无法挽回的病，我能让它好转，这不是必死的病，而是医生能让它活过来。如果病人不是死于疾病，反而死于医生之手，这与用棍棒刀刃杀人有什么区别？所以救人的功劳小，误伤的罪过大。试看栽杏叟（指董奉或泛指医者），尚且误投药物，伤了母子两条性命，何况普通人呢？然而这也是警示世人的事情。古今名医，都是生前元气充沛，如果再加以培养，就可以名登仙籍，可惜他们没能做到，为什么呢？既然已经在当时享有盛名，怎么肯虚心向地位低的人请教？况且一个人的精神是有限的，如果在忙碌中出错，误用了药物，自己也不知道错误，病人聘请医生非常艰难，幸好请到了，怎么敢议论医生的对错，即使服药有误，也归结为死者命中注定。所以运气小的过错小，运气大的过错大。学生们如果能借鉴我的话，潜心好学，将来运气小的可以变大，运气大的可以避免过错。
开之（张志聪自称或弟子代称，此处依原文语境理解为作者自述或对话者）说：纵观古今医家，有子孙显赫发达的，有子孙衰微的，大有天地之别。如果不图名声、不贪利益，虚心受益，存心救人，难道会有不长久昌盛其后代的吗！
又说：古时候称医生为“山中宰相”，是说能够调理阴阳，调和药味，掌握生死的大权罢了！《礼记》说：如果不是三代行医的家庭出身，就不服用他们的药。许学士说：是指能读三代圣贤之书。我认为世代相传，又能读书好学，就像世代为官的贵族子弟，士人的儿子恒常成为士人一样。如果仅仅守着祖传的药方，以为可以世代流传，这与按图索骥有什么不同？上天有四时的气候，地方有五方的差异，人的各种疾病，变幻多端，就拿伤寒这一病症来说，有三百八十九种治法，怎么能拘泥固执于祖传药方，能通晓变化应对时行疾病吗？赵括只会死读父亲的书，尚且导致军队失败，何况没有祖传书可读的人呢！继承祖父的事业却不好学他人之长，可以比作草庐中的诸葛亮吗？伊芳川先生说：医生不读书，纵然成为仓公、扁鹊那样的神医，终究只是技术一类的人，不是士君子。卢不远先生说：应当反复诵读这句话。（门徒弟子多为世医子弟，所以再次说这些话以告诫他们。）
The *Jingui Yaolue* (Essential Prescriptions of the Golden Cabinet) states: Among the thousands of diseases, there are no more than three categories of causes: (1) Pathogenic factors invading the meridians and entering the zang-fu organs, which constitutes the internal cause; (2) Stagnation and blockage of blood vessels in the four limbs and nine orifices, resulting from external invasion of the skin, which constitutes the external cause; (3) Injuries caused by sexual indiscretion, metal weapons, or insect and animal bites. From this detailed analysis, the origins of all diseases are fully explained. (From *Jingui Yaolue*) The second category emphasizes external causes, while regarding sexual indiscretion and dietary habits as internal causes.) Cheng Wuji of the Song Dynasty stated: There are three categories of causes for disease: (1) External causes related to Heaven, (2) Internal causes related to Humanity, and (3) Neither-internal-nor-external causes. External causes related to Heaven refer to the six excesses (Liu Yin): wind, cold, summerheat, dampness, dryness, and fire. Internal causes related to Humanity refer to the seven emotions (Qi Qing): joy, anger, worry, fear, etc., as well as improper diet and sexual fatigue. Neither-internal-nor-external causes refer to injuries from metal weapons, falls, insect/animal bites, and corporal punishment. All human diseases fall within these three categories. Shanghan (Cold Damage) is an external cause, yet the principles of the *Shanghan Lun* (Treatise on Cold Damage Disorders) comprehensively cover the six qi (wind, cold, summerheat, dampness, dryness, fire). Within it, the distinctions between exterior and interior, yin and yang, cold and heat, qi and blood, pathogenic factor and healthy qi, and deficiency and excess are thoroughly analyzed and documented. Understanding the principles of Shanghan means that the thousands of diseases do not exceed this scope. Therefore, one should begin medical studies with Shanghan, tackling the difficult aspects first, then the easy ones. Generally, diseases caused by external factors are acute and dangerous, while those caused by internal factors are slow and persistent. (Wind-stroke, malaria, dysentery, flaccidity syndrome, bi-syndrome, hernia, jue-syndrome, and various head and abdominal pains are mostly related to external causes.) Thus, a physician treating exogenous diseases can save lives or take them; a physician treating endogenous diseases may make occasional errors without immediate fatal consequences. Therefore, a physician who can treat endogenous diseases but is unfamiliar with Shanghan cannot be called a famous doctor; conversely, a physician who can treat Shanghan but is unfamiliar with endogenous diseases does not exist.
On the third, sixth, and ninth mornings of each month, I gathered my disciples to lecture on the *Huangdi Neijing* (Yellow Emperor’s Inner Canon) and the *Shanghan Lun*. After finishing the lectures, I said to the students: It is a common custom to say that practicing medicine relies entirely on fortune. I disagree. You come to study medicine; you must strive diligently in reading books and carefully investigate their principles, so as to avoid the blame of being an incompetent physician. If one relied on fortune, what profession could not be practiced? Why endure the hardships of this field! Suppose one accidentally kills an innocent person but saves hundreds; such merit cannot atone for the sin. Saving lives is the duty of a physician. Moreover, many patients have mild illnesses, some recover spontaneously, and even severe cases may be curable. Yue Ren (Bian Que) said: "I cannot bring the dead back to life, but for incurable conditions, I can restore health." This implies that diseases deemed inevitably fatal can be saved by physicians. If a patient dies not from the disease but from medical error, how is this different from killing with a club or blade? Thus, the merit of saving lives is small, while the guilt of causing harm is great. Consider Dong Feng (the Apricot Planter), who occasionally misprescribed medication, resulting in the death of a mother and child; how much more so for ordinary people? This serves as a warning to the world. Famous physicians of ancient and modern times possessed abundant vital energy in their youth; if they had continued to cultivate it, they might have achieved immortality. Alas, why did they fail? Once renowned, would they humbly learn from others? Human spirit and energy are limited; mistakes made in haste, such as incorrect prescriptions, may go unnoticed. Patients find it difficult to secure a good physician; once found, they dare not question his judgment. Even if medication errors occur, the fault is attributed to the patient's fate. Thus, minor luck leads to minor errors, while major luck leads to major errors. If students heed my words, study earnestly, their minor luck may improve, and their major errors may be avoided.
Kaizhi said: Observing physicians throughout history, some have descendants who become prominent, while others see their families decline, a difference as vast as heaven and earth. If one seeks neither fame nor profit, remains humble and receptive, and intends to save lives, how could one fail to enjoy lasting prosperity for one's descendants?
Furthermore, it was said in antiquity that physicians were called "Chancellors of the Mountains," meaning they could harmonize yin and yang, balance flavors, and hold the power of life and death. The *Book of Rites* states: "One does not take medicine from a family that has not practiced medicine for three generations." Scholar Xu interpreted this as referring to reading the classics of the Three Dynasties. I believe that inheriting a medical tradition while also studying and learning is akin to noble families where sons of scholars remain scholars. If one merely clings to ancestral prescriptions, believing them sufficient for generations, it is no different from searching for a steed according to a picture. Heaven has the qi of four seasons, and the earth has differences among five directions. Human diseases are complex and variable. Take Shanghan as an example: there are 389 methods of treatment. Can one rigidly adhere to old prescriptions and adapt to changing epidemic diseases? Zhao Kuo, who only memorized his father's writings, still suffered military defeat; how much worse for those without ancestral texts to read? Is one who inherits a grandfather's practice but refuses to learn from others comparable to Zhuge Liang in his thatched cottage? Mr. Yifangchuan said: "A physician who does not read books, even if becoming like Cang Gong or Bian Que, remains merely a technician, not a gentleman scholar." Mr. Lu Buanyuan said: "One should repeatedly reflect on these words." (Most of my disciples are children of hereditary physicians, hence I repeat this to admonish them.)