病之有形者，可望而知，有声者，可闻而知。至无形无声处，须问而知，更切而知，此治病所以赖有四诊也。然而四诊中，有正象，有反象，有真象，有假象，往往诸诊无可凭。偶得一诊以为确据者，固恃临诊时，有神明之用耳。癸巳春，余客都门，有孙姓女公子患咽痛症，前医以其胸满闷溺短赤，任用破气导湿之剂，症益剧。来延余诊，切其脉，数甚，左尺独微，知是春温邪盛，水液受耗，非滋清不可，用白虎汤，冬地汤法，加减治之而愈。愈后，旬有余日，前症复作。余诊之，身热汗出，烦躁口干，脉来滑数，舌中苔厚而黄，谂是饮食不节，温邪复聚为患，又用白虎承气汤法治之。两剂，病不减。至再诊时，望见被褥太厚，始知病所以不减故，令去其半，告以症宜凉不宜温。投剂始效，十数服而病豁然。此望而知之一证也。丙戌秋八月，余同邑城南，陆家溏陆大兴，患胸痛半年，请诊于余。面色唇舌俱赤，鼻息亦粗，脉象尤数，大致似有火郁。及问病状，渠答曰；稍感外寒，痛势连绵，必饮热烧酒，始能止痛。因知症系虚寒，一切面舌之赤，鼻息之粗，脉象之数，是饮热烧酒所致。用四逆汤理中汤等方，加减治之，其痛即平。此间而知之一证也。癸巳秋，余入都，至某太史处，闻人笑语云：你太快活，故生病矣。阅时，即有某舆夫来求诊。余切其脉，细而涩，因知所闻快活生病，殆此人也。遂用十全大补汤法补之。或以其形貌壮伟，且系劳力粗人，疑药不合。余曰；此盖色劳，其外虽强，其中实馁，非补不治。服药数剂，果大效，后询诸人，渠果香巢遍筑，如狡兔有三窟然。此闻而知之一证也。庚寅春季，余客天津，适同乡余君秋田病剧，速余往诊。上吐下泻，神识支离，不惟饮食不思，并碧霞膏亦不能吸，症象颇危。然余切其脉，虚细中尚有和缓之致，外象虽险，真气未漓。与以附子理中汤加味，吐泻即止。继进十全大补汤法，随时减增，共调治月余而愈。此切而知之一证也。比而论之，可凭者在此，即不可凭昔在彼，总恃临证时，于无可凭中，求其着实可凭处，奉为定凭而已。至于治病之法，寒者温之，热者清有之，实者泻之，虚者补之。有一病即有一法，药味无可乱投，即制方有大小，用药有轻重，亦皆各行其是，未可混施。然而有时寒热虚实，病情错出，治法亦不能不变通者，是又恃临治之人，善为权度焉。丁酉春仲，余往吴桥，为王君检予治中风时，渠夫人亦病剧，日夕惊恐，合目尤甚，畏寒不已，头裹重绵，犹觉冷风袭入骨髓，身热有汗，胸脘时觉火烧，溺赤便溏，舌苔灰腻，脉时虚缓，时滑数，时左盛，时右盛。余先用加味八珍汤法补之，继用郁芩五苓散法泻之，更间用理中汤、三黄汤法以温之清之，终以参斛汤法加味调治之，居然逐次奏功，月余丽症悉愈。或间治病如行路，一病止一路，今之路何其多?余曰：路何尝多哉，不过盘旋往复，多费周折耳。此症气血极虚，中有湿热凝聚为患，故见症错杂如此。以其气虚有湿，而用补气燥湿之剂，必至血耗：以其血虚有火，而用养血清火之剂，必至气馁。合用之不能，专任焉不得。于是或补或泻或清或温，随时以策应之，譬诸路，有直捷处，亦有曲折处，遇曲折处，仍直捷行之，必室碍而难通，惟循途曲赴焉。斯曲折之路，与直捷之路，势虽不同，及其到也则一。尝闻人传述一种怪病云，其病已延数医，每易一医，初剂必较，再剂即不效，主人束手无策，坐以待毙。噫，此殆曲折之路，误为直捷之路。故有行辄阻，天下岂真有怪病哉。所虑者，主人苦于不知，多方畏葸，旁人不知而貌为知，妄虞殷勤。此中贻误正多。放愚谓前症情形极重，竟能转危为安者，实渠子元常侍奉之力，元常于余相交有年，每谈医理，吻合无间。故余得曲折如志，与为诊治，设遇逆旅主人，虽神明如扁鹊，亦莫可如何耳。只得诿之曰；敷为之也，有命存焉而已。
疾病中有形可见的，可以通过观察得知；有声音可闻的，可以通过听诊得知。至于那些无形无声的地方，必须通过询问来了解，更要通过切脉来探查，这就是治疗疾病之所以依赖望、闻、问、切这四种诊断方法的原因。然而在这四种诊断中，既有正象，也有反象；既有真象，也有假象，往往使得各种诊断都难以作为依据。偶尔能凭借其中一种诊断作为确凿证据的，确实依赖于医生在临诊时具有神妙明察的能力。
癸巳年春天，我客居京城，有一位孙姓女子患有咽痛症。之前的医生因为她胸部胀满、小便短赤，随意使用了破气导湿的药物，导致病情更加严重。后来请我去诊治，我切按其脉搏，发现脉数非常快，唯独左尺脉微弱，知道这是春温邪气旺盛，水液受到耗损，非滋阴清热不可，于是采用白虎汤（清气分热）和冬地汤（滋阴清热）的方法，加减药物进行治疗，最终痊愈。病愈后，过了十几天，原来的症状又发作了。我再行诊治，见她身体发热、出汗、烦躁、口干，脉象滑数，舌中部苔厚且黄，深知这是饮食不节制，温邪再次聚集为患，于是又用白虎承气汤（清热泻下）的方法治疗。服用两剂药后，病情没有减轻。到了第二次复诊时，我看到她盖的被褥太厚，才明白病情不减的原因，让她去掉一半被褥，并告诉她病症适宜清凉而不宜温热。投药之后才开始见效，服用了十几次后，病势豁然开朗，完全康复。这是“望而知之”的一个案例。
丙戌年秋八月，我的同乡陆大兴住在城南陆家溏，患胸痛半年，请我为他诊治。他的面色、嘴唇和舌头都发红，鼻息也粗重，脉象尤其快，大体上看起来像是火郁证。等到询问病情，他回答说：稍微感受一点外寒，疼痛就会连绵不断，必须喝热的烧酒，才能止痛。因此我知道这个病症属于虚寒，前面提到的面色、舌头红赤，鼻息粗重，脉象快速，都是饮用热烧酒所致。于是使用四逆汤（回阳救逆）和理中汤（温中散寒）等方剂，加减治疗后，疼痛立即平息。这是“间（问）而知之”的一个案例。
癸巳年秋天，我进入京城，到某位太史府上，听到有人笑着说：“你太快乐了，所以生病了。”过了一会儿，就有一位轿夫来求诊。我切按其脉搏，脉细而涩，因此推断刚才听到的“因快乐生病”，大概指的就是这个人。于是采用十全大补汤（气血双补）的方法为他进补。有人因为他体格壮伟，又是从事体力劳动的粗人，怀疑药方不对症。我说：“这是色劳（房事过度导致的虚损），外表虽然强壮，内部其实空虚，如果不进补是无法治愈的。”服药几剂后，果然效果显著。后来向旁人打听，他果然纵欲过度，如同狡兔有三窟一样频繁。这是“闻而知之”的一个案例。
庚寅年春季，我客居天津，恰逢同乡余秋田病重，急忙请我去诊治。他上吐下泻，神识恍惚不清，不仅不想吃东西，连碧霞膏（一种外用或内服的成药/香料，此处指代某种提神或止吐之物，或指无法接受任何气味刺激）也无法吸入，症状相当危急。但是我切按其脉搏，在虚弱细微之中还有和缓之气，外在形象虽然危险，但真气尚未耗尽。给予加味的附子理中汤（温中健脾，回阳救逆），呕吐和腹泻立即停止。接着进服十全大补汤的方法，根据情况随时增减，共同调治了一个多月才痊愈。这是“切而知之”的一个案例。
综合比较来看，可以凭据的在这里，不可以凭据的在那里，总是依靠医生在临证时，在看似无可凭据的情况中，寻找确实可凭据的地方，奉为确定的依据罢了。至于治疗疾病的方法，寒证用温法，热证用清法，实证用泻法，虚证用补法。有一种病就有一种治法，药味不能乱投，即使方剂有大有小，用药有轻有重，也都各自遵循其规律，不可混淆施用。然而有时寒热虚实交错出现，治疗方法也不能不变通，这又依赖于临治之人善于权衡变通。
丁酉年仲春，我去吴桥为王检予治疗中风时，他的夫人也病重，日夜惊恐，闭眼时更甚，极度畏寒，头上裹着重重的绵帽，仍觉得冷风侵入骨髓，身体发热且有汗，胸脘部时常感觉像火烧一样，小便赤黄，大便溏薄，舌苔灰腻，脉象时而虚弱缓慢，时而滑数，时而左侧脉盛，时而右侧脉盛。我先用加味八珍汤（补气养血）的方法为她进补，继而又用郁芩五苓散（清热利湿）的方法为她泻实，中间还交替使用理中汤和三黄汤（清热燥湿）的方法来温中和清热，最后以参斛汤（益气养阴）加味进行调理，竟然逐步奏效，一个多月后所有症状全部痊愈。有人问我：治病就像走路，一种病只有一条路，现在的路怎么这么多？我说：路哪里多呢？不过是盘旋往复，多费周折罢了。这个病症气血极其虚弱，中间又有湿热凝聚为患，所以见到的症状如此错杂。因为气虚有湿，如果只用补气燥湿的药，必然会导致血耗伤；因为血虚有火，如果只用养血清火的药，必然会导致气受损。合用则不行，专任某一法也不行。于是或补或泻或清或温，随时策应，这就好比走路，有直捷处，也有曲折处，遇到曲折处，如果强行走直路，必定阻碍难通，只有沿着曲折的道路前行。这条曲折的路与直捷的路，形势虽然不同，但到达终点是一样的。
曾经听人传说一种怪病，这种病已经拖延了好几位医生，每换一位医生，第一剂药比较有效，第二剂就不见效了，主人束手无策，坐以待毙。唉，这大概是把曲折的路误认为是直捷的路。所以一行动就受阻，天下难道真有怪病吗？所担心的是，主人苦于不懂医理，多方畏惧退缩，旁人不了解却装作懂，妄自揣测，殷勤献计。这里面造成的延误非常多。所以我以为前面的病例情形极重，竟能转危为安，实在是因为他的儿子元常侍奉得力。元常与我相交多年，每次谈论医理，都吻合无间。所以我能够顺遂心意地进行曲折诊治，如果遇到像旅店主人那样不懂装懂的人干预，即使是像扁鹊那样神明的人，也无能为力。只能推脱说：“这是天意，有命存焉而已。”
Diseases that have visible forms can be known through observation (Wang), and those with audible sounds can be known through listening and smelling (Wen). As for those without form or sound, one must know them through inquiry (Wen) and further through palpation (Qie); this is why treating diseases relies on the Four Diagnostic Methods (Si Zhen: Observation, Listening/Smelling, Inquiry, Palpation). However, among these four methods, there are correct manifestations (Zheng Xiang) and reverse manifestations (Fan Xiang), true manifestations (Zhen Xiang) and false manifestations (Jia Xiang). Often, all diagnostic methods fail to provide a reliable basis. Occasionally, relying on just one method as definitive evidence indeed depends on the physician's divine perceptiveness during clinical practice.
In the spring of the Guisi year, while residing in the capital, I treated a young lady surnamed Sun who suffered from throat pain. Previous physicians, noting her chest fullness and scanty dark urine, had arbitrarily administered formulas to break Qi stagnation and guide out dampness, causing her condition to worsen. Upon my examination, her pulse was rapid (Shu), but the left Chi position was particularly weak. I deduced that this was due to flourishing Spring-Warmth pathogenic factors consuming body fluids, requiring nourishment and clearing heat. I treated her using the principles of Baihu Tang (White Tiger Decoction) and Dongdi Tang (Winter Earth Decoction), with modifications, resulting in recovery. More than ten days after recovery, the original symptoms recurred. Upon re-examination, she presented with fever, sweating, irritability, dry mouth, a slippery-rapid pulse, and a thick yellow coating on the center of the tongue. I realized this was caused by irregular diet leading to the re-accumulation of Warmth pathogens. I again treated her using the method of Baichengqi Tang (White Tiger and Da Chengqi Decoction combined). After two doses, the illness did not subside. During the second follow-up, observing that her bedding was too thick, I understood the reason for the lack of improvement. I instructed her to remove half of it and advised that her condition required cooling rather than warming. Only then did the medication take effect, and after more than ten doses, her illness cleared up completely. This is a case of "knowing through observation."
In the eighth month of autumn in the Bingxu year, Lu Daxing, a fellow townsman living at Lujia Tang south of the city, suffered from chest pain for half a year and requested my consultation. His complexion, lips, and tongue were all red, his nasal breathing was coarse, and his pulse was particularly rapid, generally resembling a Fire Stagnation pattern. However, upon inquiry, he replied that slight exposure to external cold caused continuous pain, which could only be relieved by drinking hot distilled liquor. Thus, I determined the syndrome was Deficiency-Cold. The previously mentioned redness of the face and tongue, coarse breathing, and rapid pulse were all induced by the consumption of hot liquor. I treated him with modifications of Sini Tang (Frigid Extremities Decoction) and Lizhong Tang (Regulate the Middle Decoction), after which the pain subsided immediately. This is a case of "knowing through inquiry."
In the autumn of the Guisi year, upon entering the capital, I visited the residence of a certain Grand Secretary. I heard someone say jokingly, "You are too happy, hence you became ill." Shortly after, a sedan-chair bearer came to seek treatment. Palpating his pulse, I found it fine and choppy (Se), and thus inferred that the person referred to by the comment about "becoming ill from excessive joy" was likely this individual. I treated him using the method of Shiquan Dabu Tang (Comprehensive Great Tonic Decoction) to tonify. Some doubted the prescription because of his robust physique and status as a laborer. I stated, "This is exhaustion from sexual activity (Se Lao). Although his exterior appears strong, his interior is actually deficient; it cannot be cured without tonification." After several doses, the effect was significant. Later inquiries revealed he indeed indulged excessively in sexual activities, like a cunning rabbit having three burrows. This is a case of "knowing through hearing."
In the spring of the Gengyin year, while staying in Tianjin, my fellow townsman Yu Qiutian fell severely ill, and I was urgently summoned. He experienced vomiting and diarrhea, disordered consciousness, loss of appetite for food, and even an inability to tolerate the scent of Bixia Gao (a specific medicinal paste/powder). The symptoms appeared critical. However, palpating his pulse, I detected a sense of harmony and moderation within the deficiency and fineness. Although the external signs were dangerous, the True Qi had not yet been depleted. I administered modified Fuzi Lizhong Tang (Aconite Regulate the Middle Decoction), and the vomiting and diarrhea ceased immediately. Subsequently, I used the method of Shiquan Dabu Tang, adjusting ingredients as needed, and after over a month of treatment, he recovered. This is a case of "knowing through palpation."
Comparatively speaking, what is reliable lies here, and what is unreliable lies there. It always depends on the physician, during clinical practice, to find the truly reliable aspects amidst the seemingly unreliable ones, taking them as the definitive basis. Regarding therapeutic methods, Cold is treated with Warmth, Heat with Clearing, Excess with Purging, and Deficiency with Tonifying. For every disease, there is a corresponding method; herbs should not be thrown together randomly. Whether the formula is large or small, or whether the dosage is heavy or light, each follows its own logic and should not be mixed indiscriminately. However, when Cold, Heat, Excess, and Deficiency present in a mixed manner, therapeutic methods must also be flexible. This again relies on the practitioner's ability to weigh and adapt appropriately.
In mid-spring of the Dingyou year, while traveling to Wuqiao to treat Wang Jianyu for Wind-Stroke, his wife was also critically ill. She suffered from day-and-night panic, fear of closing her eyes, extreme aversion to cold, and despite wrapping her head in heavy cotton, still felt cold wind penetrating to the bone marrow. She had fever with sweating, a burning sensation in the chest and epigastrium, dark urine, loose stools, a grayish-greasy tongue coating, and a pulse that was sometimes deficient and slow, sometimes slippery and rapid, sometimes dominant on the left, and sometimes on the right. I first treated her with modified Bazhen Tang (Eight Treasures Decoction) to tonify, followed by Yuxin Wuling San (Yu Jin, Huang Qin, and Five-Ingredient Powder with Poria) to drain damp-heat. Intermittently, I used Lizhong Tang and Sanhuang Tang (Three-Yellow Decoction) to warm and clear, finally concluding with modified Shenhu Tang (Ginseng and Dendrobium Decoction) for regulation. Gradually, the treatment took effect, and after more than a month, all symptoms resolved. Someone asked, "Treating disease is like walking; one disease corresponds to one path. Why are there so many paths now?" I replied, "Where are there many paths? It is merely winding back and forth, involving more detours. This patient had extreme Qi and Blood deficiency, compounded by the accumulation of Damp-Heat. Hence the symptoms were so complex. If one uses only Qi-tonifying and Damp-drying herbs for Qi-deficiency with Dampness, it will inevitably consume Blood. If one uses only Blood-nourishing and Fire-clearing herbs for Blood-deficiency with Fire, it will inevitably damage Qi. Neither combined use nor exclusive reliance on one method works. Therefore, one must alternate between tonifying, draining, clearing, and warming, responding flexibly. This is like walking: there are direct routes and winding routes. If one forces a direct route through a winding section, it leads to obstruction. One must follow the winding path. Though the winding path and direct path differ in shape, they lead to the same destination."
I once heard of a strange disease where multiple physicians had been consulted. Each time a new physician was engaged, the first dose showed some effect, but the second dose failed. The family was helpless, waiting for death. Alas, this is mistaking a winding path for a direct one. Thus, progress is blocked at every turn. Are there truly strange diseases in the world? What is worrying is that the family, ignorant of medicine, acts with hesitation, while bystanders pretend to understand and offer presumptuous advice, causing much delay. I believe that the previous case, though critical, turned from danger to safety largely due to the diligent care of the patient's son, Yuan Chang. Having studied medicine with me for years, Yuan Chang understood medical principles perfectly. This allowed me to proceed with the necessary complex treatment without interference. Had an interfering layperson been present, even a physician as skilled as Bian Que would have been powerless. We would have had to resign ourselves, saying, "It is fate; destiny prevails."