或问∶治病何者为难？子曰∶此非短章所能了，略举数则，可以类推。如上寒下热，上
热下
寒；表里受邪，气血交病；伏邪未尽，正气已虚；更有此脏病而治他脏者，辨证稍涉不明，
鲜不误人。何谓上寒下热？如恶风身热，又患腹痛赤痢。须先散其寒邪，再用清热之药是也
。何谓上热下寒？如咳嗽吐血，又大便清泄，脚冷等症。前贤用八味汤冷服，冷从上热所好
，桂、附能除下寒是也。何谓表里受邪，气血交病？如发寒热，又患赤痢腹痛，须表里双顾
，柴平汤加黄连、楂肉；或壮热不休，头疼恶风，腹痞拒按，须大柴胡等汤是也。其邪未尽
而正已虚，当分邪之轻重，虚之大小；补中带疏，疏中带补，必如持权操衡，方为有得。若
此脏病而治他脏者，即所谓隔一隔二之法，不外乎虚补其母，实泻其子是也。更有急病为难
，治之得当，顷刻霍然，否则移晷难挨。即如小便不通一症，其因不一。湿热癃闭，开泄太
阳，岂待言哉？东垣治一人小便不通，腹胀如臌，求生不能，求死不得。东垣深思至夜半，
忽有所得，用滋肾丸而愈。丹溪治一人，穷思极想，因见水注而悟，用吐法而瘳。二说皆载
本书，不烦重述。二公皆大名医，尚难其治如此，而况后人乎！
凉药误人，人不易觉；热药误人，一服便见。往时有患咳嗽吐血，一医用凉血之品，生
地、
丹皮之类，病者服之，喜其血止；出入加减，数十剂咳嗽不减，纳食渐少，病者不悟，竟成
腹臌而毙。呜呼！此服寒凉误人，而人不觉也。又南城李姓，病症未详，诸医罔效。延芦墟
郁某来治，用八味汤二剂而愈。明年病复作，症一如前，仍延郁治，仍用八味汤，一服而殂
。此热医误人而易见者也。前人有用热药如君子，凉药如小人之喻。所谓君子者，苟有过，
人必知之。为人则可，药关人性命，用之不当，虽君子亦何取乎？而况小人耶？
有人问：“治病中什么是最难的？”我回答说：“这并非简短的篇幅所能讲完，大致列举几则例子，就可以类推其他情况了。”比如上寒下热、上热下寒；表里同时受邪、气血同时患病；伏邪（潜伏体内的病邪）尚未清除而正气已经虚弱；更有治疗此脏疾病却从调理他脏入手的，如果辨证稍微不够明确，很少有不误人的。
什么叫上寒下热？比如恶风身热，又患有腹痛和赤色痢疾。需要先发散其寒邪，然后再用清热的药物。
什么叫上热下寒？比如咳嗽吐血，又大便清稀泄泻、脚冷等症状。前代贤人使用八味汤（金匮肾气丸）冷服，因为冷服顺应了上热之症喜凉的喜好，而桂枝、附子能去除下部的寒邪。
什么叫表里受邪、气血交病？比如发寒热，又患赤色痢疾腹痛，需要表里双顾，用柴平汤加黄连、山楂肉；或者壮热不退，头疼恶风，腹部痞满拒按，需要用大柴胡汤等方剂。
邪气未尽而正气已虚，应当区分邪气的轻重和正气的虚实程度；在补益中兼以疏泄，在疏泄中兼以补益，必须像手持秤杆称量物体一样精准平衡，才算有所心得。至于治疗此脏疾病却调理他脏的方法，就是所谓的“隔一隔二”之法，不外乎虚证补其母脏，实证泻其子脏罢了。
还有急病更难治，治疗得当，顷刻间就能痊愈，否则连一个时辰都难以熬过。就像小便不通这一症状，原因不一。若是湿热导致的癃闭（排尿困难），采用开泄太阳经气的方法，难道还需要多说吗？李东垣曾治疗一人小便不通，腹胀如鼓，求生不能求死不得。李东垣深思至半夜，忽然有所领悟，使用滋肾丸而治愈。朱丹溪治疗一人，穷思极想，因看见注水的情景而悟出道理，使用吐法而痊愈。这两种说法都记载在他们的著作中，不再赘述。这两位都是名医，尚且觉得治疗如此困难，何况后人呢！
凉药误人，人们不容易察觉；热药误人，吃一付药就能看出来。过去有患咳嗽吐血的病人，一位医生用了凉血药物，如生地黄、牡丹皮之类，病人服用后，喜欢血止住了；医生出入加减用药，几十剂后咳嗽不减，进食逐渐减少，病人没有意识到这是药物副作用，最终发展成腹臌（鼓胀）而死。唉！这就是服用寒凉药物误人而人们不觉察的例子。又有一位南城姓李的病人，病症不详，众医无效。请芦墟的郁某来治疗，用了两剂八味汤而痊愈。第二年病复发，症状与前次一样，仍请郁某治疗，仍用八味汤，结果一服药就死亡了。这就是热性药物误人且容易察觉的例子。前人有用热药比作君子、凉药比作小人的比喻。所谓君子，如果有过错，人们一定知道。作为人可以这样，但药物关乎人性命，使用不当，即使是君子般的药物又有什么可取的呢？何况是小人般的药物呢？
A question was asked: "What is the most difficult aspect in treating diseases?" I replied: "This cannot be fully explained in a short passage. I will briefly list a few examples, from which others can be inferred." For instance, cold above and heat below, or heat above and cold below; pathogenic factors affecting both the exterior and interior, with simultaneous disorders of Qi and Blood; latent pathogens (Fuxie) not yet cleared while Zhengqi (Upright Qi) is already deficient; furthermore, there are cases where disease in one Zang organ is treated by regulating another Zang organ. If pattern differentiation (Bianzheng) is slightly unclear, it is rare that such treatment does not lead to error.
What is meant by "cold above and heat below"? For example, aversion to wind with fever, accompanied by abdominal pain and bloody dysentery. One must first disperse the cold pathogen, and then use heat-clearing medicines.
What is meant by "heat above and cold below"? For example, coughing with hemoptysis, accompanied by loose watery stools and cold feet. Former sages used Bawei Tang (Eight-Ingredient Pill with Rehmannia, taken cold). The cold administration caters to the preference for coolness due to upper heat, while Guizhi (Cinnamon Twig) and Fuzi (Prepared Aconite Root) eliminate lower cold.
What is meant by "pathogens affecting both exterior and interior, with Qi and Blood simultaneously diseased"? For example, alternating chills and fever, accompanied by bloody dysentery and abdominal pain. Both exterior and interior must be addressed simultaneously, using Chai Ping Tang (Bupleurum and Pinellia Decoction) added with Huanglian (Coptis Rhizome) and Zhari Rou (Hawthorn Flesh); or if there is unremitting high fever, headache, aversion to wind, abdominal fullness and distension with tenderness upon pressure, Da Chaihu Tang (Major Bupleurum Decoction) and similar formulas should be used.
When pathogens remain but Zhengqi is already deficient, one must distinguish the severity of the pathogen and the degree of deficiency. Tonification should be combined with draining, and draining with tonifying. It must be handled with the precision of balancing weights on a scale to achieve success. Regarding treating disease in one Zang organ by regulating another, this refers to the method of "skipping one or two organs," which essentially involves tonifying the Mother organ in deficiency patterns and purging the Child organ in excess patterns.
Acute diseases are also difficult to treat. If treated correctly, recovery occurs almost instantly; otherwise, even an hour is hard to endure. Take urinary retention as an example; the causes vary. In cases of strangury caused by Damp-Heat, opening the Taiyang meridian qi is obvious and needs no further explanation. Li Dongyuan once treated a patient with urinary retention, abdominal distension like drum-tightness, who could neither live nor die. After deep contemplation until midnight, he suddenly had an insight and cured the patient using Zishen Wan (Kidney-Nourishing Pill). Zhu Danxi treated another patient who pondered deeply until inspired by seeing water being poured, curing him using the emetic method. Both accounts are recorded in their respective books and need not be repeated here. These two were renowned physicians, yet they found treatment so difficult; how much more so for later generations!
Cold-natured medicines harm people subtly, often going unnoticed; hot-natured medicines harm people visibly, showing effects after just one dose. In the past, a patient with cough and hemoptysis was treated by a physician using blood-cooling herbs such as Shengdi Huang (Rehmanniae Radix) and Mudan Pi (Moutan Cortex). The patient was pleased that the bleeding stopped. With minor adjustments over dozens of doses, the cough did not subside, appetite gradually decreased, and the patient, unaware of the cause, eventually died from abdominal distension (Guzhang). Alas! This illustrates how cold-natured medicines harm people without their awareness. Another case involved a Mr. Li from Nancheng with unspecified symptoms, unresponsive to various physicians. Yu from Luxu was invited to treat him and cured him with two doses of Bawei Tang. The following year, the illness recurred with identical symptoms. Yu was consulted again and prescribed the same Bawei Tang, but the patient died after the first dose. This illustrates how hot-natured medicines harm people and the errors are easily seen. Ancients compared hot medicines to Junzi (gentlemen) and cold medicines to Xiaoren (petty men). A gentleman, if he errs, people will surely know. As a person, this is acceptable; but medicine concerns life and death. If used improperly, even a "gentlemanly" medicine has its drawbacks; how much worse, then, for a "petty man" medicine?