万病莫逃于伤寒。伤寒之祖。断推仲景。而后人辄议仲景之书。详于风寒。略于温热。
予谓
此非惟不知仲景。并亦不知伤寒。按仲景本素问及八十一难等书而作伤寒论。考难经云。伤
寒有五。一曰中风。二曰伤寒。三曰湿温。四曰温病。五曰热病。其所苦各不同形。既曰伤
寒有五。则伤寒只属病之总名。而五者之中。病又不专属寒因。若风。若湿。若温。若热。
同隶伤寒有五条下。仲景作书而以伤寒命名者。义取诸此。今从仲景原文。反复互勘其实仲
景大法。合之难经伤寒有五之例。若合符契。其法总从太阳病辨起。如所云太阳病发热汗出
恶风脉缓者。名为中风。太阳病。或已发热。或未发热。必恶寒体重呕逆。脉阴阳俱紧者。
名曰伤寒。太阳病发热而渴。不恶寒者为温病。太阳病关节疼痛而烦。脉沉而细者。此名湿
痹。太阳中热者 是也。其人汗出恶寒身热而渴也。以此分发难经伤寒有五之例。界划分
明。仲景伤寒论。此伤寒字即难经伤寒有五之伤寒。而伤寒类中专有一种太阳病。或已发热。
或未发热。必恶寒体重呕逆。脉阴阳俱紧者。独名之曰伤寒。此外若风若湿若温若热。同属
伤寒之类而各异其名。欲识伤寒之病。须先定伤寒之名。语云名不正则言不顺。故予急正
其名以冠于篇首。
各种疾病没有能逃脱于伤寒范畴的。论及伤寒的始祖，必定推崇张仲景。然而后人往往议论张仲景的著作，详细论述了风寒，而简略论述了温热。
我认为，这不仅是不知道张仲景，也是不知道什么是伤寒。考察张仲景撰写《伤寒论》是依据《素问》和《难经》等书籍。考据《难经》记载：伤寒有五种类型。第一种叫中风（风邪伤表），第二种叫伤寒（寒邪伤表），第三种叫湿温（湿热相搏），第四种叫温病（温热之邪），第五种叫热病（火热之邪）。它们所导致的痛苦表现各不相同。既然说“伤寒有五种”，那么“伤寒”只是疾病的总称。而在上述五种之中，致病原因并不专属于寒邪。如果是风、如果是湿、如果是温、如果是热，都同属于“伤寒”这一大类下的五条分支。张仲景撰写此书并以“伤寒”命名，其义理正是取自于此。
现在依照张仲景的原文，反复互相考证，其实张仲景的大法，与《难经》中“伤寒有五”的体例，如同符契般吻合。其辨证方法总从太阳病（足太阳膀胱经受邪所致的病证）开始辨析。例如文中所说：“太阳病，出现发热、汗出、恶风（怕风吹）、脉象缓者，称为中风。”“太阳病，或者已经发热，或者尚未发热，必定恶寒（怕冷）、身体沉重、呕吐逆气，脉象寸关尺三部皆紧者，称为伤寒。”“太阳病，发热且口渴，不恶寒的，称为温病。”“太阳病，关节疼痛且烦躁，脉象沉而细的，此名为湿痹（湿邪阻滞经络）。”“太阳中热者，即暍病（中暑）。其人汗出、恶寒、身热且口渴。”以此分发对应《难经》中“伤寒有五”的体例，界限划分分明。
张仲景的《伤寒论》，其中的“伤寒”二字，即指《难经》中“伤寒有五”的广义伤寒。而在伤寒类中，专门有一种情况：太阳病，或已发热，或未发热，必恶寒、体重、呕逆，脉阴阳俱紧者，单独称之为“伤寒”。除此之外，若是风、若是湿、若是温、若是热，都同属伤寒的类别，但名称各异。想要认识伤寒这种病，必须先确定伤寒的名称。俗话说：名分不正，言语就不顺当。所以我急于纠正其名，将其置于篇章之首。
All diseases fall within the scope of Shanghan (Cold Damage). In terms of the originator of Shanghan studies, Zhang Zhongjing is undoubtedly the foremost figure. However, later scholars often critique Zhang Zhongjing's work, stating that it details Wind-Cold (Feng-Han) but neglects Warmth-Heat (Wen-Re).
I contend that this view demonstrates not only a lack of understanding of Zhang Zhongjing but also a fundamental misunderstanding of Shanghan. Zhang Zhongjing composed the *Shanghan Lun* (Treatise on Cold Damage) based on texts such as the *Suwen* (Basic Questions) and the *Nanjing* (Classic of Difficult Issues). According to the *Nanjing*, "Shanghan comprises five types": 1. Zhongfeng (Wind Strike), 2. Shanghan (Cold Damage), 3. Shiwen (Damp-Warmth), 4. Wenbing (Warm Disease), and 5. Rebing (Heat Disease). The suffering associated with each manifests differently. Since it is stated that "Shanghan has five types," "Shanghan" serves merely as the general category name for these diseases. Within these five categories, the etiology is not exclusively cold. Etiologies such as Wind, Dampness, Warmth, and Heat all fall under the five branches of the broad concept of Shanghan. Zhang Zhongjing named his treatise "Shanghan" precisely because its meaning encompasses this broader classification.
By cross-referencing Zhang Zhongjing's original text repeatedly, it becomes evident that his major principles align perfectly with the framework of "Shanghan has five types" from the *Nanjing*. His diagnostic method generally begins with the differentiation of Taiyang disease (disease pattern resulting from pathogenic invasion of the Foot-Taiyang Bladder meridian). For instance, he states: "In Taiyang disease, if there is fever, sweating, aversion to wind, and a moderate pulse, it is named Zhongfeng." "In Taiyang disease, whether fever has already appeared or not, there must be aversion to cold, heaviness of the body, vomiting, and a tight pulse at both yin and yang positions; this is named Shanghan." "In Taiyang disease, if there is fever and thirst without aversion to cold, it is named Wenbing." "In Taiyang disease, if there is joint pain, irritability, and a deep, fine pulse, it is named Shibi (Damp Bi)." "Taiyang Zhongre refers to Ye disease (heatstroke); the patient exhibits sweating, aversion to cold, high fever, and thirst." This distribution corresponds clearly to the five types of Shanghan outlined in the *Nanjing*, with distinct boundaries.
The term "Shanghan" in Zhang Zhongjing's *Shanghan Lun* refers to the broad sense of Shanghan as defined in the *Nanjing*'s "five types." However, within the category of Shanghan, there is a specific presentation: Taiyang disease where fever may or may not have occurred, accompanied by inevitable aversion to cold, body heaviness, vomiting, and a tight pulse at both yin and yang positions, which is specifically designated as "Shanghan." Other conditions caused by Wind, Dampness, Warmth, or Heat belong to the broader category of Shanghan but bear different names. To understand the disease of Shanghan, one must first clarify the definition of the name. As the saying goes, "If the name is not correct, language is not in accordance with truth." Therefore, I urgently seek to rectify this nomenclature and place it at the beginning of this chapter.