伤寒，一名卒病。卒，暴也，阴阳不和，卒暴为病。凡恶寒，发热，头痛，骨疼，呕吐，烦渴，皆伤寒也。
因内伤而伤寒者，病之至重者也。内伤伤寒，有性命之虞。治法一以温补元气为主，不效，更当大温补，毋
发散虚其经脉，毋消导耗其中土，毋寒凉损其阳和。虽有外证，必察其内。察内者，探本澄源之大道，舍轻从
重之至理也。如是，十全其七。若妄加消散，不愈，然后温补，药不纯正，方不画一，旋消旋补，倏凉倏温，
如是十死其七。夫伤寒，大病也。而世医施治之法，无非消散寒凉，病可一二剂而愈者，必至于十数剂；始为
发散，继则消磨，终则攻下，原本壮实而病在三阳者，其身或不死，身虽不死，而耽延时日，野狼狈已极矣。
且人以胃气为本，
若病伤寒，更以胃气为先。世医不明此理，凡遇伤寒，必曰内有食也。夫食为养命之本，有食何妨？况无病则
能食，有病则不能食；无病则嗜食，有病则恶食。恶食而不能食，不可强与；若饥而欲食，盒饭与之。如必
曰不可食也，复投消食宽胸、挨磨攻下之药，人岂金石哉！夫食入于胃，随食随消，若有停滞，自然不宁，
即当呕吐。仲师《伤寒论》云∶宿食在上脘者，当吐之。由此观之，则在上脘，是为宿食，若归中脘，便腐
化传导，无宿食矣。病患数日不食，岂复有宿食之理？若胸膈胀满，按之而痛，非上焦虚寒，即气机不转，当
益其气机，温其三焦，正气流行，则胸膈舒畅。粗工不知，亦曰有食，如果有食，何以始病之时，按之不痛？
既病之后，数日不食，按之反痛？按之而痛，真气虚也，奈何妄行消导，以为积垢内停？欲使便出，屡屡攻下，
岂知肠胃内虚，所下者不过溏泄稀粪耳！夫攻下便稀，是肠虚也，而又不知，尤必曰此旁流也。嗟嗟！旁流
二字，论中并无，即有旁流，必燥粪内结，而旁水自流，非登厕便稀之为旁流也。夫宿食旁流之证，或百中
有一，岂可视为常事哉？世之治伤寒者，惟散、惟消、惟清、惟泄，罔顾其本，但治其末；消、散、清、泄殆
尽，见病虚寒，然后调补。执一定不移之死法，治变化无方之伤寒，舍生机活泼之至道，用杀伐刀锯之惨刑，
能不悲哉！故治病必求于本，而伤寒治本之法，难以言传，识六气之标本，明经络之浅深，更
合经论而会通之，其庶几乎！
伤寒，又被称为卒病。“卒”意为突然、暴烈，指阴阳失调，突然猛烈地引发疾病。凡是出现恶寒、发热、头痛、骨节疼痛、呕吐、心烦口渴等症状的，都属于伤寒范畴。
因内部正气先伤而感受外邪导致的伤寒，是病情最为严重的类型。内伤兼感伤寒，有危及生命的风险。治疗原则应以温补元气为主；如果效果不明显，更应当加大温补的力度。切勿使用发散药物损伤经脉，切勿使用消导药物耗损脾胃（中土），切勿使用寒凉药物损害阳气与和顺之气。虽然存在外部症状，但必须仔细审视内部状况。审视内部，是探究本源、澄清根源的大道，是舍弃轻微病症而重视根本重症的最高真理。若能如此，治愈率可达十分之七。如果胡乱使用消散攻伐之法，病情未愈之后才转而温补，此时药性不纯正，方剂不统一，一边消散一边补益，忽而寒凉忽而温热，这样会导致十分之七的患者死亡。
伤寒是大病。然而世俗医生施治的方法，无非是消散和寒凉。原本一两剂药就能痊愈的病，必然拖延到十几剂；起初用发散法，接着用消磨法，最后用攻下法。原本体质壮实且病在三阳经的患者，身体或许不会死亡，但即便不死，也会延误时日，狼狈不堪到了极点。
况且人以胃气为根本，若患伤寒，更应将顾护胃气放在首位。世俗医生不明白这个道理，凡遇到伤寒，必定说体内有食积。食物是维持生命的基础，有食积有什么妨碍呢？何况没有病时能进食，有病时不能进食；没有病时喜爱进食，有病时厌恶进食。厌恶进食且无法进食，不可强行喂食；如果饥饿想进食，就应当给予食物。如果一定说不能吃，再投用消食宽胸、磨积攻下的药物，人难道是金石做的吗！食物进入胃中，随吃随消化，如果有停滞，自然会产生不适，甚至导致呕吐。张仲景在《伤寒论》中说：“宿食停留在上脘的，应当采用吐法。”由此看来，停留在上脘的才是宿食，如果食物进入中脘，就会腐熟转化并传导排出，就不存在宿食了。病人几天不进食，哪里还会有宿食的道理呢？
如果胸膈部位胀满，按压时疼痛，这不是上焦虚寒，就是气机运转不畅，应当补益气机，温煦三焦，使正气流行，那么胸膈就会舒畅。粗劣的医生不知道这些，也说是有食积。如果真的有食积，为什么在发病初期，按压时不痛？既然生病后，几天不进食，按压时反而疼痛？按压时疼痛，是因为真气虚弱，怎么能胡乱使用消导法，认为是积滞污垢停留在体内呢？为了让大便排出，屡次使用攻下法，哪里知道肠胃内部已经空虚，排出的不过是稀烂的粪便罢了！大便变稀，说明肠道空虚，而医生却不知道，还一定说是“热结旁流”。唉！“旁流”这两个字，在《伤寒论》原文中并没有出现，即使有旁流，也一定是燥屎结于内部，而旁边的水液自行流出，并不是上厕所拉稀便叫做旁流。所谓宿食旁流的证候，也许百人中才有一例，怎么能把它当作常规情况来处理呢？
世上治疗伤寒的医生，只知发散、只知消导、只知清热、只知泄下，不顾及疾病的根本，只治疗表面现象；等到发散、消导、清热、泄下几乎用尽，见到病人呈现虚寒症状后，才开始调补。拿着固定不变的死板方法，去治疗变化无常的伤寒病，舍弃了生机活泼的最高道理，使用了如刀锯般残酷的杀伐手段，能不令人悲哀吗！所以治病必须探求根本，而治疗伤寒的根本方法，难以用言语完全传达，只有认清六气的标本关系，明白经络的深浅层次，再结合经典理论融会贯通，大概才能接近正道吧！
Shanghan (Cold Damage), also known as "Zu Bing" (Sudden Disease). "Zu" means sudden or violent; it refers to a disease caused by the disharmony of Yin and Yang, manifesting suddenly and violently. Any condition presenting with aversion to cold (E Han), fever (Fa Re), headache (Tou Tong), bone pain (Gu Teng), vomiting (Ou Tu), vexation and thirst (Fan Ke) belongs to the category of Shanghan.
When Shanghan occurs due to prior internal injury (Nei Shang), it is the most severe form of illness. Internal injury complicated by external cold invasion poses a threat to life. The treatment principle must focus primarily on warming and tonifying Yuan Qi (Original Qi). If ineffective, even stronger warming and tonification should be employed. One must not use dispersing methods that damage the meridians, nor digestive-resolving methods that deplete the Spleen/Stomach (Central Earth), nor cooling methods that impair Yang Qi and harmonious energy. Although external symptoms exist, one must carefully examine the internal state. Examining the interior is the great way to probe the root and clarify the source; it is the highest logic to discard minor issues and prioritize the critical root cause. By following this approach, seven out of ten cases can be cured. Conversely, if one recklessly applies resolving and attacking methods, and only turns to warming and tonifying after the condition fails to improve, the medicinal properties will be impure, and the prescriptions inconsistent—oscillating between resolving and tonifying, cooling and warming. This approach leads to death in seven out of ten cases.
Shanghan is a major disease. However, the treatment methods employed by contemporary physicians are invariably dispersing and cooling. A condition that could be cured in one or two doses inevitably drags on for over ten doses: initially using dispersing methods, then resolving methods, and finally purgative methods. Even if patients with robust constitutions and diseases confined to the Three Yang channels survive, they suffer extreme exhaustion and prolonged suffering.
Furthermore, humans rely on Stomach Qi (Wei Qi) as their foundation. In cases of Shanghan, protecting Stomach Qi must be the priority. Contemporary physicians fail to understand this principle; upon encountering Shanghan, they invariably claim there is food stagnation (Shi Ji) internally. Food is the basis of sustaining life; what harm is there in having food? Moreover, when healthy, one eats well; when ill, appetite diminishes. When healthy, one craves food; when ill, one dislikes food. If one dislikes and cannot eat, one should not force feeding. If hungry and desiring food, food should be provided. Insisting that food must not be eaten, and instead administering drugs to resolve food and open the chest, grind away stagnation, and purge, treats the human body as if it were metal or stone! Food enters the Stomach and is digested immediately. If stagnation occurs, discomfort naturally arises, potentially leading to vomiting. Master Zhang Zhongjing stated in the *Shanghan Lun*: "For retained food in the Upper Jiao, emesis should be induced." From this, we see that retained food exists only in the Upper Jiao. Once food reaches the Middle Jiao, it rots, transforms, and conducts outwards, meaning no retained food remains. If a patient has not eaten for several days, how could retained food possibly exist?
If there is distension and fullness in the chest and diaphragm, accompanied by pain upon pressure, this is either deficiency-cold in the Upper Jiao or impaired Qi mechanism movement. One should benefit the Qi mechanism and warm the San Jiao (Triple Burner) so that righteous Qi flows freely, thereby relieving chest and diaphragmatic discomfort. Incompetent physicians, unaware of this, still attribute it to food stagnation. If it were truly food stagnation, why was there no pain upon pressure at the onset of the disease? After falling ill and fasting for several days, why does pressure now cause pain? Pain upon pressure indicates deficiency of True Qi. How can one recklessly apply resolving methods, assuming accumulated filth is retained internally? To induce bowel movements, repeatedly using purgatives ignores the fact that the intestines and stomach are already empty internally; the discharged material is merely loose, watery stool. Loose stool indicates intestinal emptiness. Yet, ignorant physicians still insist this is "Pang Liu" (Side-flowing diarrhea). Alas! The term "Pang Liu" does not appear in the *Shanghan Lun*. Even if side-flowing diarrhea existed, it would imply dry feces bound internally with liquid flowing around them, not simply loose stools during defecation. Cases of retained food causing side-flowing diarrhea occur perhaps once in a hundred; how can this be treated as a common occurrence?
Physicians treating Shanghan today only employ dispersing, resolving, clearing, and purging methods, neglecting the root while treating the branch. Only after exhausting these dispersing, resolving, clearing, and purging methods, and observing signs of deficiency-cold, do they begin to regulate and tonify. Adhering to rigid, unchanging methods to treat the ever-changing Shanghan, abandoning the vibrant path of vitality for the cruel execution of killing and sawing tactics—is this not tragic? Therefore, treating disease requires seeking the root. The method for treating the root in Shanghan is difficult to convey fully in words. One must comprehend the root and branch relationships of the Six Qi (Liu Qi), understand the depth and superficiality of the meridians, and integrate these insights with classical theories to approach the correct path.