夫两感于寒而病者，必死之候也。如一日太阳与少阴俱病，则发热恶寒，头痛口
干，烦躁而渴；二日阳明与太阴俱病，则腹满身热，谵语不食，睡卧不宁；三日少阳与
厥阴俱病，则胁痛耳聋，囊缩而厥，水浆不入，不省人事，总阴阳俱病，表里俱伤，腑
脏之气不得通于上下，荣卫之精，不得行于内外，病至六日，六经俱绝，不可救治。然
何为而两感也。如一日太阳与少阴俱病，则太阳者，腑也。邪自背俞而入，人之所共知
也。少阴者，脏也。邪自鼻息而入，人所不知也。鼻气通于天，故寒邪无形之气从鼻而
入，肾为水脏，物以类聚，故肾受之。《经》曰∶天之邪气，感则害人五脏。内外两感，
脏腑俱病，欲表之则有里，欲下之则有表，表里既不能一治，故云两感者不治。然所禀
有虚实，所感有浅深，虚而感之深者，必死。实而感之浅者，犹有可治。表症多者，
先解其表；里症多者，先攻其里，所谓治有先后，要在临时变通，治得其宜，恒多无害。
夫人之平时，荣卫周流，无少间断，一旦邪气入内，阻碍正气，不得流行，郁而为
热。仲景曰，在表发汗，在中和解，在里攻下，随其所而驱散之，不过使邪热退而正气
复行，此先贤立法之准绳也。然前人壮实，尚堪任此攻下，今人虚弱，何能当此推敲？
使元气既受伤于病，复受伤于药，惟图不治之治可也。况人之经络，三阳三阴，分布一
身，邪之所凑，岂有定所？黄仲理云∶风寒六气之邪伤人，或入于阳经，或中于阴络，
孰为之先？孰为之后？乌可专以太阳为受邪之始？故各经皆能受邪，但太阳经受邪居
多，为差等尔，故取仲景六经见证七方，发散以先之。若夫阴经受邪，则不复传变，惟
用前方温经散寒而已，惟阳经受邪，初用麻黄、桂枝以表散之。传入半表半里，又取小
柴胡汤和解以继之。邪传于里，理宜攻下，又取大柴胡汤、调胃承气等汤下之，此治真
伤寒表中里三症之大略也。至于冬温为病，非其时而有其气也。冬时严寒，当君子闭
藏，而反发泄于外，专用补药而带表药，如补中益气之类。
凡是感受寒邪而患“两感病”的，都是必死的征候。比如第一天太阳经与少阴经同时发病，就会出现发热、恶寒、头痛、口干、烦躁且口渴的症状；第二天阳明经与太阴经同时发病，就会出现腹部胀满、身体发热、说胡话（谵语）、不能进食、睡眠躺卧不安稳；第三天少阳经与厥阴经同时发病，就会出现胁肋疼痛、耳聋、阴囊收缩、四肢厥冷、无法进水浆、神志昏迷不省人事。总之，这是阴阳两经都受病，表里都受损，脏腑之气不能上下通达，营卫之精不能行于内外。病发展到第六天，六经之气全部衰竭，就无法救治了。
那么为什么会发生“两感”呢？比如第一天太阳经与少阴经同时发病：太阳经属于腑，邪气从背部的俞穴侵入，这是人们所共知的；少阴经属于脏，邪气从鼻息侵入，这是人们所不知道的。鼻气上通于天，所以无形的气候寒邪从鼻子进入；肾是水脏，同类相聚，所以肾受到邪气侵袭。《内经》说：“天的邪气，感应后就会伤害人的五脏。”内外同时受邪，脏腑都生病，想要解表治疗则顾虑里有病，想要攻下治里则顾虑表有病，表里既然不能单独治疗，所以说两感病是不治之症。
然而，人的体质禀赋有虚实之分，感受邪气的深浅也不同。体质虚弱且感受邪气深的，必定死亡；体质充实且感受邪气浅的，还有可治的希望。如果表证多，就先解除表邪；里证多，就先攻逐里邪，这就是所谓的治疗有先后顺序，关键在于根据临时情况灵活变通，只要治疗得当，通常大多没有危害。
人在平时，营气和卫气周身循环流动，没有片刻间断。一旦邪气侵入体内，阻碍正气，使其不能正常运行，郁结而化热。张仲景说，邪气在表用发汗法，在经（半表半里）用和解法，在里用攻下法，随邪气所在部位将其驱散，不过是使邪热消退而正气恢复运行，这是先贤确立治疗法则的标准准则。
然而，前人体质壮实，尚能承受这种攻下的治疗；今人体质虚弱，怎么能承受这样的推敲（指药物攻伐）？如果元气既被疾病损伤，又被药物损伤，只能追求那种“不治之治”（即通过调养而非猛药来恢复）的方法了。况且人的经络，三阳经和三阴经分布全身，邪气聚集的地方，怎么会有固定的位置？黄仲理说：“风寒等六淫邪气伤人，有的侵入阳经，有的中伤阴络，谁先谁后？怎么能专门以太阳经作为受邪的开始？”所以各条经脉都能受邪，只是太阳经受邪的情况居多，以此作为等级差别罢了。因此，选取张仲景六经见证的七种方剂，先用于发散邪气。如果是阴经受邪，就不再传变，只使用前面的方剂温经散寒即可；只有阳经受邪，初起时用麻黄、桂枝来解表发散。邪气传入半表半里，又取小柴胡汤来和解以接续治疗。邪气传入里部，理应攻下，又取大柴胡汤、调胃承气汤等方剂来攻下，这是治疗真正伤寒表、中、里三症的大略原则。至于冬温病，是非其时而有其气（冬天应冷反暖）。冬季严寒，本该是阳气闭藏的时候，反而发泄于外，专用补药并配合解表药，如补中益气汤之类。
Those who suffer from "Lianggan" (Double Exposure) due to cold pathogenic factors are in a critical, invariably fatal condition. For instance, on the first day, if both the Taiyang (Greater Yang) and Shaoyin (Lesser Yin) meridians are affected, symptoms such as fever, aversion to cold, headache, dry mouth, restlessness, and thirst will occur; on the second day, if both the Yangming (Yang Brightness) and Taiyin (Greater Yin) meridians are affected, abdominal fullness, body heat, delirium (Zhenyu), inability to eat, and restless sleep will manifest; on the third day, if both the Shaoyang (Lesser Yang) and Jueyin (Terminal Yin) meridians are affected, hypochondriac pain, deafness, contraction of the scrotum, cold limbs, inability to take in fluids, and unconsciousness will appear. In summary, this represents simultaneous disease of both Yin and Yang, damage to both exterior and interior, obstruction of Qi communication between Zang and Fu organs, and blockage of Ying (Nutritive) and Wei (Defensive) essence circulation inside and outside. By the sixth day, when the Qi of all six meridians is exhausted, the condition becomes incurable.
Then, why does "Lianggan" occur? Taking the example of the first day with simultaneous Taiyang and Shaoyin involvement: The Taiyang meridian belongs to the Fu (Hollow) organs; pathogenic factors enter via the Shu (Transport) points on the back, which is commonly known. The Shaoyin meridian belongs to the Zang (Solid) organs; pathogenic factors enter via nasal respiration, which is less understood. Nasal Qi connects to Heaven; thus, formless cold Qi enters through the nose. The Kidney is the Water organ; like attracts like, so the Kidney receives the pathogen. As stated in the *Classic* (*Jing*): "Heavenly pathogenic factors, upon contact, harm the Five Zang organs." When both interior and exterior are simultaneously affected, and both Zang and Fu organs are diseased, treating the exterior is contraindicated by the interior disease, and purging the interior is contraindicated by the exterior disease. Since exterior and interior cannot be treated separately, it is said that Lianggan is incurable.
However, constitutional endowment varies in deficiency or excess, and the depth of pathogenic invasion differs. Those with deficiency constitution and deep invasion will inevitably die. Those with robust constitution and shallow invasion may still be treatable. If exterior symptoms predominate, resolve the exterior first; if interior symptoms predominate, purge the interior first. This implies treatment has a sequence, relying on flexible adaptation to changing conditions. If treatment is appropriate, harm is usually avoided.
Normally, Ying and Wei Qi circulate continuously without interruption. Once pathogenic factors invade internally, they obstruct Zheng Qi (Upright Qi), preventing normal flow, leading to stagnation and heat generation. Zhang Zhongjing stated: "If in the Exterior, induce sweating; if in the Meridians (Middle/Shaoyang), harmonize; if in the Interior, purge downward." Disperse pathogens according to their location, merely allowing pathogenic heat to recede and Zheng Qi to resume circulation. This is the standard established by ancient sages.
However, ancients were robust and could withstand such purgative treatments; modern people are weak and cannot endure such harsh manipulation. If Yuan Qi (Primal Qi) is injured by the disease and further injured by medicine, one should only aim for the "treatment of non-treatment" (restorative care). Moreover, the meridians—Three Yang and Three Yin—are distributed throughout the body. Where pathogenic factors gather, how can there be a fixed location? Huang Zhongli said: "Wind, Cold, and other Six Excesses injuring humans may enter Yang meridians or strike Yin collaterals. Who comes first? Who follows? How can we exclusively regard the Taiyang meridian as the starting point of pathogenic invasion?" Therefore, all meridians can receive pathogens, though Taiyang receives them most frequently, serving as a reference grade. Thus, select the seven formulas from Zhang Zhongjing’s Six Meridian patterns for initial dispersal. If Yin meridians are affected, transmission ceases; use previous formulas to warm meridians and disperse cold. Only if Yang meridians are affected initially use Ephedrae Herba (Mahuang, 麻黄) and Cinnamomi Ramulus (Guizhi, 桂枝) for exterior dispersal. If pathogens transmit to the Half-Exterior Half-Interior stage, use Xiao Chaihu Tang (Minor Bupleurum Decoction) to harmonize subsequently. If pathogens transmit to the Interior, purging is indicated; use Da Chaihu Tang (Major Bupleurum Decoction), Tiaowei Chengqi Tang (Regulate the Stomach and Direct Downward Decoction), etc., to purge downward. This outlines the general principles for treating true Shanghan (Cold Damage) involving Exterior, Middle, and Interior syndromes. Regarding Dongwen (Winter Warmth) disease, it arises from inappropriate climate ("having its Qi out of season"). In winter, severe cold should lead to closure and storage (of Yang Qi); instead, leakage occurs outward. Use tonifying herbs combined with exterior-releasing herbs, such as Buzhong Yiqi Tang (Tonify the Middle and Boost Qi Decoction).