庄生言道在屎溺。岂道果在屎溺耶。然就屎溺而言。亦可以见道。道固无不在也。是故诸书论大便。亦因
之以诊病焉。愚谓屎以得黄色之正者为中。得干湿之中者为常。知其正。则知其偏。知其常。则知其变矣。
设因饮食之殊。而有形色之异。亦其变之常也。诊之之法。诸书以为暴注下迫。皆属于热。澄彻清冷。皆属
于寒。出黄如糜者肠中热。肠鸣渗泄者肠中寒。濡泄者因于湿。飧泄者伤于风。粪如 溏者。泄泻之病。大
肠寒。粪如羊矢者。噎膈之病。大肠枯。如水倾下者属湿。完谷不化者为寒。泄利无度者肠绝。下利清谷者
里寒。自利清水。色纯青者少阴病。急下之证。行其大便。燥且结者。胃家实。下后之征。诸下血先便后血为
远血。先血后便为近血。从肠中来者。其色红。从胃中来者。其色黑。白痢者。属乎气。赤痢者。属乎血。便色白
者。大肠泄。便脓血者。小肠泄。泄青白者。大肠虚。便肠垢者。大肠实。纯下青水者。风痢。泄如蟹渤者。气痢。黑
如豆汁者。湿痢。黄如鱼脑者。积痢。白如鼻涕者。虚痢。黑如鸡肝者。蛊疰痢。五液注下。痢兼五色者。脾弱之
证。谷道不闭。黄汁长流者。肠绝之征。腹胀泄蛔者。疳胀。粪黑如狂者。蓄血。痢下蛔未死者。胃气未绝。痢下
蛔已死者。胃气将绝。卧而遗屎。不知觉者死。病而大便如污泥者死。此皆因便以诊病也。然难经以入者
为实出者为虚。是则便闭者。形气虽不足。而病气有余。便泄者。病气虽有余。而形气不足。故标本病传论
曰。先病而后泄者。治其本。先泄而后生他病者。治其本。小大不利。治其标。小大利。治其本。先小大不利。而
后生病者。治其本。病发而有余。本而标之。先治其本。后治其标。病发而不足。标而本之。先治其标。后治其
本。伤寒论因之有急当救里。急当救表焉。合四诊而观之。标本之分。先后之辨。其如示诸掌乎。
庄子说“道”存在于屎尿之中。难道“道”真的只在屎尿里吗？然而，从屎尿的角度来看，也可以体悟到“道”。因为“道”本来无处不在。所以，各种医书论述大便，也是借此来诊断疾病。我认为，大便呈现黄色为正常色泽，干湿适中为常态。知道了正常的标准，就能知道异常的偏差；知道了常态，就能了解病变的情况。如果因为饮食不同而出现形色差异，这也是变化中的常理。诊断的方法，各书认为：突然剧烈腹泻且肛门急迫坠胀的，都属于热证；排泄物清澈寒冷稀薄的，都属于寒证。粪便像糜烂物一样的，是肠中有热；肠鸣且泄泻的，是肠中有寒。濡软泄泻是由于湿邪所致；完谷不化的飧泄是由于风邪损伤。粪便像稀泥一样的，是泄泻病，属于大肠寒。粪便像羊粪球一样的，是噎膈病，属于大肠枯燥。像水一样倾泻而下的，属于湿证。完全不消化的完谷不化属于寒证。泄泻无度的，是肠道功能衰竭（肠绝）。下利清谷（排出未消化的食物）的是里寒证。自行泻出清水，颜色纯青的，是少阴病，需要紧急攻下的证候。大便干燥且结硬的，是胃家实证，这是经过攻下治疗后的征象。各种便血，先排便后出血的叫远血，先出血后排便的叫近血。血液来自肠道的，颜色鲜红；来自胃部的，颜色黑。白痢属于气分病变，赤痢属于血分病变。大便色白的，是大肠泄；大便脓血的，是小肠泄；泄泻物青白色的，是大肠虚；大便混有黏液的，是大肠实；纯下青色水的，是风痢；泄泻像螃蟹泡沫一样的，是气痢；黑色像豆汁一样的，是湿痢；黄色像鱼脑一样的，是积痢；白色像鼻涕一样的，是虚痢；黑色像鸡肝一样的，是蛊疰痢。五种体液同时注下，痢疾兼见五色，是脾弱的证候。肛门失禁，黄汁长流不止的，是肠绝的征象。腹胀并排出蛔虫的，是疳胀。粪便黑得像发狂的人（指瘀血内阻）的，是蓄血证。痢疾排出蛔虫但未死的，说明胃气未绝；痢疾排出蛔虫已死的，说明胃气将绝。睡着时遗屎且不知觉的，主死；患病期间大便像污泥一样的，主死。这些都是通过观察大便来诊断疾病。然而，《难经》认为，邪气入内为实证，正气外出为虚证。因此，大便闭结的，虽然形体元气不足，但病邪之气有余；大便泄泻的，虽然病邪之气有余，但形体元气不足。所以《标本病传论》说：先患病而后发生泄泻的，治疗其本病；先泄泻而后产生其他疾病的，治疗其本病。大小便不通利的，治疗其标病；大小便通利的，治疗其本病。先出现大小便不利，而后产生其他疾病的，治疗其本病。疾病发作表现为邪气有余的，先治本后治标；疾病发作表现为正气不足的，先治标后治本。《伤寒论》据此提出了“急当救里”和“急当救表”的原则。结合望、闻、问、切四诊来观察，分清标本，辨别先后，就像看手掌一样清楚明白。
Zhuangzi stated that the "Dao" (Way/Principle) exists in excrement and urine. Does this mean the Dao is truly confined to excrement and urine? However, by observing excrement and urine, one can also perceive the Dao, for the Dao is inherently omnipresent. Therefore, various medical texts discuss defecation as a means to diagnose diseases. I consider that stool with a yellow hue represents the normal standard, and consistency that is neither too dry nor too wet represents the norm. Knowing the standard allows one to identify deviations; knowing the norm allows one to understand pathological changes. If variations in color and form arise due to differences in diet, these are considered normal variations. Regarding diagnostic methods, various texts state: sudden violent diarrhea with tenesmus (urgent pressing sensation at the anus) belongs to Heat syndromes; clear, cold, and thin discharges belong to Cold syndromes. Stool resembling porridge indicates Heat in the intestines; borborygmus (intestinal rumbling) with diarrhea indicates Cold in the intestines. Soft and loose diarrhea is caused by Dampness; Sun-xie (diarrhea with undigested food) is caused by Wind injury. Stool like mud indicates Diarrhea disease due to Intestinal Cold. Stool resembling sheep pellets indicates Yige (dysphagia with regurgitation) due to Dryness of the Large Intestine. Watery diarrhea pouring down belongs to Dampness. Undigested food in stool indicates Cold syndrome. Unremitting diarrhea indicates Exhaustion of the Intestines (Chang Jue). Downward discharge of clear undigested food indicates Interior Cold syndrome. Spontaneous discharge of pure green water indicates Shaoyin Disease, a condition requiring urgent purgation. Hard and knotted stool indicates Excess in the Stomach family (Wei Jia Shi), a sign after purgative treatment. Various forms of hematochezia: bleeding after defecation is called Remote Blood (Yuan Xue); bleeding before defecation is called Near Blood (Jin Xue). Blood originating from the intestines is red; blood originating from the stomach is black. White dysentery relates to Qi disorders; red dysentery relates to Blood disorders. White-colored stool indicates Large Intestine leakage; pus and blood in stool indicate Small Intestine leakage; blue-white discharge indicates Large Intestine Deficiency; stool mixed with mucus indicates Large Intestine Excess; pure discharge of blue water indicates Wind Dysentery; discharge resembling crab bubbles indicates Qi Dysentery; black discharge resembling bean juice indicates Damp Dysentery; yellow discharge resembling fish brain indicates Accumulation Dysentery; white discharge resembling nasal mucus indicates Deficient Dysentery; black discharge resembling chicken liver indicates Gu Zhu Dysentery. Simultaneous discharge of five fluids and dysentery presenting five colors indicate Spleen Weakness. Incontinence of the anus with continuous flow of yellow fluid is a sign of Intestinal Exhaustion. Abdominal distension with expulsion of roundworms indicates Gan Distension. Stool black as if mad (indicating blood stasis) indicates Blood Accumulation (Xu Xue). Expulsion of live roundworms during dysentery indicates that Stomach Qi is not yet exhausted; expulsion of dead roundworms indicates that Stomach Qi is about to be exhausted. Enuresis during sleep without awareness indicates death. Illness accompanied by stool resembling sludge indicates death. These are all methods of diagnosing diseases through observation of stool. However, the *Nanjing* (Classic of Difficult Issues) states that inward progression indicates Excess, while outward discharge indicates Deficiency. Thus, constipation indicates that although physical Qi is deficient, pathogenic Qi is excessive; diarrhea indicates that although pathogenic Qi is excessive, physical Qi is deficient. Therefore, the *Treatise on Syndrome Root and Branch Transmission* states: If illness precedes diarrhea, treat the root; if diarrhea precedes other illnesses, treat the root. If urination and defecation are obstructed, treat the branch; if they are unobstructed, treat the root. If obstruction of urination and defecation precedes other illnesses, treat the root. When an illness manifests with Excess, treat the root first and the branch second; when it manifests with Deficiency, treat the branch first and the root second. The *Shanghan Lun* (Treatise on Cold Damage) adopts these principles, proposing "Urgently Rescue the Interior" and "Urgently Rescue the Exterior." By integrating the four diagnostic methods (Inspection, Auscultation/Olfaction, Inquiry, and Palpation), distinguishing between root and branch, and determining priority, clarity is achieved as easily as viewing one's palm.