《难经》云。问而知之之谓工。工于问者。即其现症以求其病源。定其病名。察
其病所。明其病情。度其病势。防其病变。兹必先
问其口渴与否。以胃为十二经之海。凡伤寒传变。必归阳明。伤寒证治。全藉阳
明。欲知里症之寒热。全在渴。不渴。辨之。此勘伤寒之精要也。于诊法上为第
五要诀。凡症属虚寒者。口多不渴。症属实热者。口多燥渴。其常也。若论其变。凡
渴喜热饮者。皆属痰饮阻中。否则气不化津。渴喜冷冻饮料者。饮多者火就燥。饮少者湿
化火。阳明实热之渴。大渴引饮。太阴湿热之渴。渴不引饮。少阴虚热之渴。口燥而
渴不消水。厥阴风火之渴。口苦而渴则消水。自利而渴者。阳明热泻。自利不渴者。
太阴寒泻。胃中液干而欲饮。饮必喜冷而能多。膀胱蓄水而欲饮。饮必吐水而不多。
先渴后呕者。水停心下。先呕后渴者。火烁胃液。口中干而消渴者。总属肝胃热病。
口中和而不渴者。多属脾肾寒症。
《内经》云。中气不足。溲便为之变。变也者。如中气不足以御寒。溲则澄澈清
冷。甚则膀胱不约而遗溺。便则溏泻飧泄。甚则大小肠直倾而洞泄。中气不足以制热。溲则
水液混浊。甚则膀胱不利为癃。便则胶闭燥结。甚则大小肠胶结为痢。
【廉勘】观察二便。西医于诊断上最为注重。谓二便中往往含有霉菌微虫。必以化
学药品。投入二便之中。细细辨析。以判其病毒之所在。此种诊断。实堪效法。凡肠寒
者溺白。肠热者溺黄。清白如冷水者为阴寒。浑白如米泔者为湿热。红黄色者为实热。
淡黄色者为虚热。深红老黄者为肝阳盛。浅红淡黄者为肾阴虚。清长而利者。心阳虚而
肾气下陷也。短涩而痛者。心火盛而膀胱热结也。溺自遗而不知者。病必死。溺极多而
虚烦者。病亦危。小儿由睡中遗溺者。谓之尿床。肾与膀胱虚寒也。小儿初溲黄赤色。
落地良久。凝如白膏者。谓之溺白。肝热逼成肾疳也。如饮一溲一。色亦凝如白膏。味
甜无臭者。三消症中之下消也。溺时点滴。尿管痛如刀割者。砂淋、石淋、血淋、膏淋
、劳淋等之五淋症也。轻为湿火。重为淋毒。溺时不痛。色凝如膏。细白稠粘者。精浊
之候。色如米泔。混浊滑流者。溺浊之候。一为房事伤肾。一为湿火下注。太阳蓄血在
膀胱。验其小便之利与不利。阳明蓄血在肠胃。验其大便之黑与不黑。大抵虚寒之证。
大便必或溏或泻。实热之证。大便必既燥且结。故凡大便形如鸭粪而稀者寒湿。形如蟹
渤而粘者暑湿。下利清谷。有生腥气者。为阴寒。有酸臭气者。为积热。大便色青。形
稀而生腥气重者为脾肾虚寒。汁粘而臭秽气重者为肝胆实热。大便老黄色者为实热。淡
黄色者为虚热。大便红如桃浆者为血热。黑如胶漆者为瘀热。大便白色者属脾虚。亦主
胆黄。酱色者属脾湿。亦主肠垢。大便褐色者火重。黑色者火尤重。大便酸臭如坏醋者
伤食滞。腥臭如败卵者伤乳积。大便急迫作声者小肠热。肛门热灼而痛者直肠热。
【荣斋按】问大便应了解其稀硬度、数量、颜色、有没有血或粘液。普通腹泻的大
便是稀的（水样）。数量很多。而痢疾病患的大便，则是很少而有血、粘液或脓。霍乱
病患的大便好象淘米水。同时，还应问大便时有没有痛苦，腹痛还是肛门痛？有没有“
里急后重”的现象。（里急后重，是直肠里一种想解大便的感觉，而实在又解不出大便
来，常见于痢疾病患。）
《难经》说：通过询问来了解病情，这就叫作“工”（高明的医生）。善于提问的医生，就是根据患者现有的症状来探求病因，确定病名，察看病位，明确病情，推测病势，预防病变。这里必须先问患者是否口渴。因为胃是十二经脉的海，凡是伤寒病的传变，最终都会归于阳明经。伤寒证的诊治，完全依赖于对阳明经的判断。想要知道里证（体内脏腑的病变）的寒热性质，全在于观察口渴与否。这是辨析伤寒的关键要点，在诊法中列为第五个重要诀窍。凡是属于虚寒性质的病症，口中大多不渴；凡是属于实热性质的病症，口中大多干燥且渴，这是常理。如果论及其变化：凡是喜欢喝热水的，都属于痰饮阻滞在中焦，否则就是气不能化生津液；喜欢喝冷冻饮料的，喝得多的属于火邪就燥（火热之邪消耗津液），喝得少的属于湿邪化火。阳明经实热导致的口渴，表现为大渴且大量饮水；太阴经湿热导致的口渴，表现为口渴但不想多饮水；少阴经虚热导致的口渴，表现为口燥且渴但不能消解水液；厥阴经风火导致的口渴，表现为口苦且渴且能消解水液。自下利（腹泻）而口渴的，属于阳明经的热性腹泻；自下利而不口渴的，属于太阴经的寒性腹泻。胃中津液干枯而想喝水，喝水一定喜欢冷饮且能多喝；膀胱蓄水（水液代谢障碍）而想喝水，喝水一定呕吐出水且喝不多。先感到口渴然后发生呕吐的，是水饮停聚在心下（胃脘部）；先发生呕吐然后感到口渴的，是火热灼伤胃中津液。口中干燥且出现消渴（多饮多尿）症状的，总属肝胃热病。口中感觉平和且不渴的，多属脾肾寒症。
《内经》说：中气不足，大小便就会发生变化。所谓变化，比如中气不足以抵御寒冷，小便就会清澈寒冷，严重时膀胱约束无力而导致遗尿，大便就会溏泻或完谷不化，严重时大小肠直接倾泄导致洞泄（严重的水样腹泻）。中气不足以制约热邪，小便就会浑浊，严重时膀胱气化不利导致癃闭（排尿困难或不通），大便就会胶结闭塞干燥，严重时大小肠胶结形成痢疾。
【廉勘按】观察二便，西医在诊断上最为重视，认为二便中往往含有霉菌或微小寄生虫，必须用化学药品投入二便中进行细致分析，以判断病毒的所在。这种诊断方法，确实值得效法。凡是肠道寒冷的，尿液发白；肠道有热的，尿液发黄。清亮如冷水的是阴寒，浑浊如米泔水的是湿热，红黄色的是实热，淡黄色的是虚热，深红老黄的是肝阳亢盛，浅红淡黄的是肾阴虚。小便清长且通畅的，是心阳虚而肾气下陷；小便短涩且疼痛的，是心火盛而膀胱热结。小便失禁且不知晓的，病必死；小便极多且伴有心烦的，病亦危重。小儿在睡梦中遗尿的，称为尿床，属于肾与膀胱虚寒。小儿刚排出的尿液呈黄赤色，落地良久后凝固如白膏状的，称为溺白，属于肝热逼迫形成肾疳。如果喝多少尿多少，颜色也凝固如白膏，味道甜而无臭味的，是三消症中的下消症。排尿时点滴而出，尿道疼痛如刀割的，是砂淋、石淋、血淋、膏淋、劳淋等五淋症。轻的为湿火，重的为淋毒。排尿时不痛，颜色凝固如膏，细白稠粘的，是精浊的表现；颜色如米泔水，混浊滑流的，是溺浊的表现。前者因房事损伤肾脏所致，后者因湿火下注所致。太阳经蓄血在膀胱，通过检验小便的通利与否来判断；阳明经蓄血在肠胃，通过检验大便的黑与不黑来判断。大致而言，虚寒的证候，大便必定或溏或泻；实热的证候，大便必定既干燥又结块。所以，凡是大便形状像鸭粪且稀薄的，属于寒湿；形状像蟹渤（一种带壳水生动物，此处指代某种形态）且粘稠的，属于暑湿。下利排出未消化的食物，有生腥气味的，属于阴寒；有酸臭气味的，属于积热。大便颜色青，形状稀薄且生腥味重的，属于脾肾虚寒；汁液粘稠且臭味秽重的，属于肝胆实热。大便呈老黄色的属于实热，淡黄色的属于虚热。大便红如桃浆的属于血热，黑如胶漆的属于瘀热。大便白色的属于脾虚，也主胆黄（黄疸的一种）。酱色的属于脾湿，也主肠垢。大便褐色的火邪重，黑色的火邪尤重。大便酸臭如坏醋的，是伤食停滞；腥臭如败卵的，是伤乳积滞。大便急迫有声的，是小肠热；肛门热灼且疼痛的，是直肠热。
【荣斋按】询问大便应了解其稀硬度、数量、颜色，以及是否有血或粘液。普通腹泻的大便是稀的（水样），数量很多。而痢疾病患的大便，则是很少且有血、粘液或脓。霍乱病患的大便好像淘米水。同时，还应问排便时有没有痛苦，是腹痛还是肛门痛？有没有“里急后重”的现象。（里急后重，是直肠里一种想解大便的感觉，而实在又解不出大便来，常见于痢疾病患。）
According to the *Nan Jing* (Classic of Difficult Issues), "To know through inquiry is called 'Gong' (a skilled physician)." A physician skilled in inquiry seeks the source of the disease based on current symptoms, determines the disease name, observes the location of the pathology, clarifies the condition, estimates the trend of the disease, and prevents complications. Here, one must first ask whether the patient feels thirsty. The Stomach is the sea of the twelve meridians; in the transmission of Shanghan (Cold Damage) diseases, pathogens inevitably return to the Yangming channel. The diagnosis and treatment of Shanghan entirely rely on the Yangming. To determine the cold or heat nature of interior syndromes (pathological changes within the internal organs), one must fully observe thirst or lack thereof. This is the essence of distinguishing Shanghan and constitutes the fifth major principle in diagnostic methods. Generally, for deficiency-cold syndromes, there is often no thirst; for excess-heat syndromes, there is often dryness and thirst. This is the normal pattern. Regarding variations: Those who prefer hot drinks usually have Phlegm-Fluids obstructing the middle jiao, or otherwise, Qi fails to transform into body fluids. Those who prefer cold drinks: if they drink large amounts, it indicates Fire pathogen seeking dryness (consuming body fluids); if they drink small amounts, it indicates Dampness transforming into Fire. Thirst caused by Yangming Excess-Heat manifests as great thirst with a desire to drink copiously. Thirst caused by Taiyin Damp-Heat manifests as thirst without a desire to drink much. Thirst caused by Shaoyin Deficiency-Heat manifests as dry mouth and thirst that does not resolve with water intake. Thirst caused by Jueyin Wind-Fire manifests as bitter taste in the mouth and thirst that resolves with water intake. Spontaneous diarrhea with thirst belongs to Yangming Heat-diarrhea; spontaneous diarrhea without thirst belongs to Taiyin Cold-diarrhea. Dryness of stomach fluids leading to desire to drink results in a preference for cold drinks and high volume intake. Water retention in the Bladder (water metabolism disorder) leading to desire to drink results in vomiting of ingested water and low volume intake. Thirst followed by vomiting indicates Water-Fluids stagnating below the heart (epigastrium). Vomiting followed by thirst indicates Fire scorching stomach fluids. Dry mouth accompanied by Xiao Ke (Wasting-Thirst syndrome characterized by polydipsia and polyuria) generally belongs to Liver-Stomach Heat disease. A neutral feeling in the mouth without thirst mostly belongs to Spleen-Kidney Cold syndromes.
The *Nei Jing* (Inner Canon) states: "Insufficiency of Middle Qi causes changes in urination and defecation." Such changes include: when Middle Qi is insufficient to resist Cold, urine becomes clear and cold; severely, the Bladder loses its restraining function leading to enuresis, and stool becomes loose or contains undigested food; severely, the intestines pour out directly causing severe watery diarrhea. When Middle Qi is insufficient to restrain Heat, urine becomes turbid; severely, Bladder Qi transformation fails leading to strangury (difficulty or inability to urinate), and stool becomes sticky, closed, and dry; severely, the intestines become stuck forming dysentery.
[Lian Kan's Note]: Observing urination and defecation is most emphasized in Western medicine diagnostics, as these excreta often contain fungi or micro-parasites. Chemical reagents are used to analyze them carefully to locate viruses. This diagnostic method is indeed worthy of emulation. Intestinal Cold leads to white urine; Intestinal Heat leads to yellow urine. Clear like cold water indicates Yin-Cold; turbid like rice wash water indicates Damp-Heat; red-yellow indicates Excess-Heat; pale yellow indicates Deficiency-Heat; deep red and old yellow indicates Hyperactive Liver-Yang; light red and pale yellow indicates Kidney-Yin Deficiency. Clear, long, and smooth urination indicates Heart-Yang Deficiency with sinking Kidney-Qi. Short, scanty, and painful urination indicates Excessive Heart-Fire and Heat knotting in the Bladder. Involuntary urination without awareness indicates a fatal condition. Excessive urination with vexation indicates a critical condition. Enuresis during sleep in children is called bedwetting, indicating Kidney and Bladder Deficiency-Cold. Freshly passed urine that is yellow-red and coagulates into a white paste-like substance after lying for a while is called "Ni Bai" (White Urine), indicating Liver-Heat forcing Kidney consumption. If the patient drinks one part and urinates one part, with color coagulating like white paste, sweet taste and odorless, it is Xia Xiao (Lower Wasting-Thirst) among the Three Xiao syndromes. Dribbling urination with urethral pain like knife-cutting indicates the Five Lin Syndromes (Sand, Stone, Blood, Grease, Labor Lin). Mild cases are Damp-Fire; severe cases are Lin-Toxin. Painless urination with color coagulating like paste, fine, white, and viscous indicates Jing Zhuo (Essence Turbidity); color like rice wash water, turbid and slippery, indicates Niao Zhuo (Urine Turbidity). The former is due to kidney injury from sexual activity; the latter is due to downward pouring of Damp-Fire. Sun-Tai accumulation of blood in the Bladder is verified by the patency or impatency of urine; Yang-Ming accumulation of blood in the intestines is verified by the blackness or non-blackness of stool. Generally, deficiency-cold syndromes present with loose or diarrheal stools; excess-heat syndromes present with dry and bound stools. Therefore, stool resembling duck feces and thin indicates Cold-Damp; stool resembling crab mud and sticky indicates Summer-Heat Damp. Diarrhea passing undigested food with a raw fishy smell indicates Yin-Cold; with a sour foul smell indicates Accumulated Heat. Green-colored, thin stool with strong raw fishy smell indicates Spleen-Kidney Deficiency-Cold; sticky juice with heavy foul smell indicates Liver-Gallbladder Excess-Heat. Old yellow stool indicates Excess-Heat; pale yellow indicates Deficiency-Heat. Red stool like peach pulp indicates Blood-Heat; black like glue/lacquer indicates Stasis-Heat. White stool belongs to Spleen Deficiency and also Gallbladder Jaundice. Sauce-colored belongs to Spleen Dampness and also intestinal mucus. Brown stool indicates heavy Fire; black stool indicates even heavier Fire. Sour-foul stool like spoiled vinegar indicates Food Stagnation; fishy-foul like rotten eggs indicates Milk Accumulation. Urgent defecation with sound indicates Small Intestine Heat; burning anal pain indicates Rectal Heat.
[Rong Zhai's Comment]: When asking about defecation, one should understand its consistency (loose/firm), quantity, color, and presence of blood or mucus. Ordinary diarrhea presents with loose (watery) stools in large quantities. Dysentery patients present with small amounts of stool containing blood, mucus, or pus. Cholera patients present with stools resembling rice washing water. Additionally, one should ask if there is pain during defecation, whether it is abdominal pain or anal pain, and if there is a sensation of "tenesmus" (Tense urgency with incomplete evacuation). (Tenesmus is a rectal sensation of wanting to defecate but being unable to pass stool, commonly seen in dysentery patients.)