客有病伤寒。下利。身热。神昏多困。谵语。不得眠。或者见其下利。以谵语为郑声。皆阴
虚证也。予诊其脉曰此承气汤证也。众皆愕然曰下利服承气。仲景法乎。答曰。仲景云下利而谵
语者。有燥屎也。属小承气汤。乃投以小承气。得利止。而下燥屎十二枚。俄得汗解。
论曰。内经云微者逆之。甚者从之。逆者正治。从者反治。从少从多。观其事也。帝曰何谓
反治。岐伯曰寒因寒用。通因通用。王冰以为大热内结。注泻不止。热宜寒疗。结伏须除。以寒
下之。结散利止。此寒因寒用也。小承气止利。正合此理。
丙午岁。商人张皓。季夏得疾。胸项多汗。四股时冷。头痛谵语。予诊其脉。关前濡。关后
数。断曰当作湿温治。盖先受暑。后受湿。暑湿相搏。是谓湿温。投以白虎加参。次以白虎苍术。
头痛渐退。足渐温。汗渐止。数日愈。此病名贼邪。误服药则死。
论曰。或者难云。何谓贼邪。予曰。难经论五邪。有实邪。虚邪。正邪。微邪。贼邪。从后
来者为虚邪。从前来者为实邪。从所不胜者为贼邪。从所胜者为微邪。自病者为正邪。又曰假令
心病中暑者为正邪。中湿得之为贼邪。今心先受邪。而湿胜之。水克火。从所不胜。斯为贼邪。
五邪之最逆者也。难经有云湿温之脉。阳濡而弱。阴小而急。濡弱见于阳部。湿气搏暑也。小急
见于阴部。暑气湿蒸也。故经曰暑湿相搏。名曰湿温。是为贼邪也。
有一位客人患有伤寒。出现腹泻，身体发热，神志昏迷且精神疲倦，胡言乱语，无法入睡。有人看到患者腹泻，认为胡言乱语是郑声（虚证时的语言低微断续），都认为是阴虚证。我诊察患者的脉象后说，这是承气汤证。众人都感到惊讶，说：“腹泻服用承气汤，符合张仲景的法则吗？”我回答说：“张仲景说过，腹泻而伴有胡言乱语的，是因为体内有燥屎。属于小承气汤证。”于是投用小承气汤，患者排出大便后腹泻停止，并排出了十二枚干燥坚硬的粪便。不久之后，患者出汗而病愈。
论述说：《内经》说，病情轻微的采用逆治法，病情严重的采用从治法。逆治法是正治，从治法是反治。顺从或逆反的程度，要观察病情的具体情况。黄帝问：什么是反治？岐伯说：用寒凉药治疗具有假寒症状的病证（寒因寒用），用通利药治疗具有通泄症状的病证（通因通用）。王冰认为，大热内结，导致泻下不止。热症应当用寒凉药物治疗，结伏的热邪必须清除。用寒凉药攻下，结散则利止。这就是“寒因寒用”。小承气汤止住腹泻，正符合这个道理。
丙午年，商人张皓，在夏末患病。胸部和颈部多汗，四肢时常发冷，头痛，胡言乱语。我诊察他的脉象，关前脉濡软，关后脉数。判断说应当作为湿温病来治疗。因为先感受暑邪，后感受湿邪，暑湿相互搏结，这叫做湿温。投用白虎加人参汤，接着使用白虎加苍术汤。头痛逐渐消退，脚部逐渐回暖，汗液逐渐停止，几天后痊愈。这种病名叫贼邪，误服药物就会死亡。
论述说：有人责难问道：什么是贼邪？我说：《难经》论述五邪，有实邪、虚邪、正邪、微邪、贼邪。从后来者为虚邪，从前来者为实邪，从所不胜者为贼邪，从所胜者为微邪，自病者为正邪。又说：假如心病中暑为正邪，中湿得之为贼邪。现在心先受邪，而湿邪胜之，水克火，从所不胜，这就是贼邪。五邪中最逆乱的。《难经》有云：湿温病的脉象，阳部脉濡弱，阴部脉小而急。濡弱见于阳部，是湿气搏结暑气；小急见于阴部，是暑气蒸腾湿气。所以经文说：暑湿相互搏结，名叫湿温。这就是贼邪。
A guest suffered from Shanghan (Cold Damage). He presented with diarrhea, fever, mental confusion with fatigue, delirious speech, and insomnia. Some observers, seeing the diarrhea and attributing the delirium to Zhengsheng (a sign of deficiency characterized by low, indistinct speech), concluded that it was a Yin deficiency syndrome. I examined his pulse and stated that this was a Chengqi Tang syndrome. The crowd was astonished, asking, "Is administering Chengqi Tang for diarrhea in accordance with Zhang Zhongjing's method?" I replied, "Zhang Zhongjing stated: 'In cases of diarrhea accompanied by delirium, there is dry feces retained in the intestines. This belongs to the Xiao Chengqi Tang syndrome.'" Consequently, I administered Xiao Chengqi Tang (Minor Order the Qi Decoction). After defecation, the diarrhea ceased, and twelve pieces of dry, hard feces were passed. Shortly thereafter, he perspired and recovered.
The commentary states: The *Neijing* (Inner Canon) says, "For mild conditions, use contrary treatment; for severe conditions, use following treatment." Contrary treatment is standard treatment; following treatment is paradoxical treatment. One must observe the circumstances to determine whether to follow or oppose. The Yellow Emperor asked, "What is meant by paradoxical treatment?" Qibo answered, "Use cold to treat cold [symptoms]; use unblocking to treat unblocking [symptoms]." Wang Bing interpreted this as: When intense heat is internally bound, causing incessant diarrhea, heat should be treated with cold herbs, and the trapped heat must be eliminated. By using cold purgatives, the binding disperses and the diarrhea stops. This is "using cold to treat cold." Xiao Chengqi Tang stopping the diarrhea perfectly aligns with this principle.
In the year Bingwu, the merchant Zhang Hao fell ill at the end of summer. He had excessive sweating on the chest and neck, coldness in the four limbs, headache, and delirium. I examined his pulse: the position before the cun (guan anterior) was Ru (Soggy), and the position after the cun (guan posterior) was Shu (Rapid). I diagnosed it as Wet-Warmth disease to be treated accordingly. This occurred because he first contracted Summerheat, then Dampness. The struggle between Summerheat and Dampness is termed Wet-Warmth. I administered Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng), followed by Baihu Cangzhu Tang (White Tiger Decoction plus Atractylodes Rhizome). His headache gradually subsided, his feet warmed, and sweating stopped. He recovered after several days. This disease is named Zei Xie (Robber Pathogen); if misdiagnosed and mistreated, it leads to death.
The commentary states: Someone challenged, saying, "What is Zei Xie?" I replied, "The *Nanjing* (Classic of Difficult Issues) discusses five types of pathogens: Shi Xie (Excess Pathogen), Xu Xie (Deficiency Pathogen), Zheng Xie (Direct Pathogen), Wei Xie (Mild Pathogen), and Zei Xie (Robber Pathogen). Coming from what follows is Xu Xie; coming from what precedes is Shi Xie; coming from what one cannot overcome is Zei Xie; coming from what one can overcome is Wei Xie; originating from one's own organ is Zheng Xie. Furthermore, if Heart disease results from Summerheat, it is Zheng Xie; if it results from Dampness, it is Zei Xie. Now, the Heart is first affected by pathogenic factors, and Dampness prevails. Water overcomes Fire, coming from what cannot be overcome; thus, it is Zei Xie. It is the most adverse among the five pathogens. The *Nanjing* states: In Wet-Warmth, the Yang pulse is Ru and weak, and the Yin pulse is small and rapid. Ru and weak appearing in the Yang portion indicates Dampness struggling with Summerheat; small and rapid appearing in the Yin portion indicates Summerheat steaming Dampness. Therefore, the classics say: Summerheat and Dampness struggling together are named Wet-Warmth. This is Zei Xie."