二便为一身之门户，无论内伤外感，皆当察此，以辨其寒热虚实。盖前阴通膀胱之道，
而其利与不利，热与不热，可察气化之强弱，凡患伤寒而小水利者，以太阳之气未剧，即吉
兆也。后阴开大肠之门，而其通与不通，结与不结，可察阳明之实虚，凡大便热结而腹中坚
满者，方属有余，通之可也。若新近得解而不甚干结，或旬日不解而全无胀意者，便非阳明
实邪。观仲景曰∶大便先硬后溏者不可攻。可见后溏者，虽有先硬，已非实热，
矧夫纯溏而连日得后者，又可知也。若非真有坚燥痞满等证，则原非实邪，其不可攻也明矣。
一、凡小便，人但见其黄，便谓是火，而不知人逢劳倦，小水即黄；焦思多虑，小水亦
黄；泻痢不期，小水亦黄；酒色伤阴，小水亦黄。使非有或淋或痛，热证相兼，不可因黄便
谓之火，余见逼枯汁而毙人者多矣。经曰∶中气不足，溲便为之变，义可知也。若小水清利
者，知里邪之未甚，而病亦不在气分，以津液由于气化，气病则小水不利也。小水渐利，则气化可知，最为吉兆。
一、大便通水谷之海，肠胃之门户也。小便通血气之海，冲任水道之门户也。二便皆主
于肾，本为元气之关，必真见实邪，方可议通议下，否则最宜详慎，不可误攻。使非真实而
妄逐之，导去元气，则邪之在表者反乘虚而深陷，病因内困者必由泄而愈亏。所以凡病不足
，慎勿强通。最喜者小便得气而自化，大便弥固者弥良。营卫既调，自将通达，即大肠秘结
旬余，何虑之有？若滑泄不守，乃非虚弱者所宜，当首先为之防也。
二便（大小便）是身体的门户，无论是内伤还是外感疾病，都应当观察二便的情况，以此来辨别病证的寒热虚实。前阴（尿道口）连通膀胱的通道，通过观察小便的通利与否、是否有热象，可以判断气化功能的强弱。凡是患伤寒病而小便通利的，说明太阳经的气血没有受到严重损伤，这是吉兆。后阴（肛门）是大肠的门户，通过观察大便的通畅与否、是否结滞，可以判断阳明经的虚实。凡是因热邪结聚导致大便干硬且腹部坚满的，才属于实证，可以采用攻下法治疗。如果是最近刚解大便且并不十分干结，或者十天半个月不解大便但完全没有腹胀感觉的，这就不是阳明实证。看张仲景说：“大便先干后稀的，不可用攻下法。”由此可见，大便后半段稀溏的，即使前面干硬，也已经不是实热证了，更何况那些纯稀溏且连续多日排便的人呢？如果不是真正出现坚硬、干燥、痞塞、胀满等症状，那就原本就不是实证，显然不可使用攻下法。
一、关于小便，人们往往只看到颜色发黄，就认为是火证，却不知道人在劳累疲倦时，小便就会发黄；思虑过度焦躁时，小便也会发黄；发生腹泻痢疾时，小便也会发黄；酒色过度损伤阴液时，小便也会发黄。如果没有伴随淋沥涩痛等热证表现，就不能仅仅因为小便黄就断定是火证。我见过许多因为误判为火证而逼迫排出枯涸之汁导致死亡的案例。《内经》说：“中气不足，会导致大小便异常”，这个道理是可以理解的。如果小便清长通利，说明体内的邪气不严重，且病不在气分，因为津液的生成和输布依赖于气化功能，气机生病则小便不利。小便逐渐变得通利，说明气化功能恢复，这是最好的吉兆。
一、大肠传导水谷，是肠胃的门户；膀胱排泄尿液，关联血气与冲任脉的水道，也是其门户。大小便都由肾所主，本是元气的关键所在。必须确凿地见到实证，才可以讨论通利或攻下，否则最应该详细谨慎，不可错误地使用攻伐之法。如果不是真正的实证却妄自攻逐，会耗损元气，那么停留在体表的邪气反而会乘虚深入体内，原本因内部困阻而生的病因，也必然因为泄泻而更加亏损。所以凡是身体虚弱的病症，千万不要强行通利攻下。最理想的状态是小便得气而自然化生，大便保持一定的固摄能力反而更好。营卫之气调和之后，自然会通达顺畅，即使大肠便秘十几天，又有什么可担忧的呢？如果滑脱失禁、不能固守，这就不适合虚弱体质的人，应当首先加以预防。
The urination and defecation (urinary and bowel functions) serve as the gates of the body. Regardless of whether the etiology is internal injury or external contraction, one must observe these two excretions to differentiate between cold-heat and deficiency-excess patterns. The anterior yin (urethral opening) connects with the pathway of the Bladder; observing whether urination is unobstructed or obstructed, and whether there is heat or not, allows one to assess the strength of Qi transformation (Qi Hua). In cases of Cold Damage (Shanghan) where urination is free, it indicates that the Qi of the Taiyang (Greater Yang) channel has not been severely compromised, which is a favorable omen. The posterior yin (anus) opens into the Large Intestine; observing whether defecation is smooth or blocked, and whether stool is consolidated or not, allows one to assess the deficiency-excess status of the Yangming (Yang Brightness) channel. Only when dry stool is bound by heat resulting in a hard and full abdomen does this constitute an Excess pattern, for which purgative methods may be applied. However, if stool was passed recently and is not very dry, or if no bowel movement occurs for ten days yet there is absolutely no sensation of abdominal distension, this is not a Yangming Excess syndrome. As Zhang Zhongjing stated: "When stool is initially hard but becomes loose later, it should not be attacked with purgatives." This shows that when the latter part of the stool is loose, even if the beginning was hard, it is no longer a true Heat-Excess pattern. How much more so for those who pass purely loose stool continuously over several days? Unless there are genuine signs of hardness, dryness, epigastric fullness, and distension, it is fundamentally not an Excess pattern, making it clear that purgation is contraindicated.
First, regarding urination, people often see yellow urine and immediately attribute it to Fire, unaware that fatigue and overwork cause yellow urine; excessive anxiety and worry cause yellow urine; diarrhea and dysentery cause yellow urine; and sexual excess damaging Yin causes yellow urine. Unless accompanied by symptoms such as strangury or pain indicating concurrent Heat syndromes, one cannot conclude it is Fire merely based on color. I have witnessed many deaths caused by forcing out withered fluids under the mistaken assumption of Fire. The Classic states: "Deficiency of Middle Qi leads to abnormalities in urination and defecation," which clarifies the meaning. If urine is clear and flows freely, it indicates that pathogenic factors inside are not severe and the disease does not reside in the Qi level, since body fluids depend on Qi transformation for their generation and distribution; if Qi is diseased, urination becomes difficult. Gradual improvement in urinary flow indicates the restoration of Qi transformation, which is the most auspicious sign.
Second, the Large Intestine transmits water and grain, serving as the gate of the stomach and intestines; the Bladder excretes urine, relating to the Sea of Blood and Qi, and serves as the gate for the Chong and Ren vessels' water pathways. Both urination and defecation are governed by the Kidney, acting as the critical juncture of Yuan Qi (Original Qi). One may only consider promoting drainage or using purgatives after confirming a genuine Excess pattern; otherwise, extreme caution and thoroughness are required to avoid erroneous attack. If non-genuine Excess conditions are wrongly treated with purgation, Original Qi will be drained away. Consequently, pathogens remaining in the exterior may sink deeper due to the deficiency, and etiologies trapped internally will become further depleted through diarrhea. Therefore, in cases of Deficiency, one must strictly avoid forced purgation. The most desirable state is when urine transforms naturally upon receiving Qi, and stool retains its firmness. Once Ying (Nutritive) and Wei (Defensive) Qi are harmonized, natural unblocking will occur spontaneously. Even if constipation persists for more than ten days, what is there to worry about? Conversely, slippery incontinence and inability to retain stool are unsuitable for those with Deficiency; prevention should be prioritized.