《伤寒》所列六经，与《素·热病论》不同。热病论根据气行之脉络言，故所着症，与《
灵·
经脉篇》义合。《伤寒论》根据邪入之次序言，故所着症，与《灵·经脉篇》义不合。经脉三
阳经皆有头痛，阳明始有恶寒，而仲景乃皆入之太阳，更以胃实为正阳明；经脉嗜卧属足太
阴
，而仲景乃谓少阴病欲寐；经脉渴而欲饮，饥不能食，属足少阴，而仲景乃谓厥阴病消渴，
饮不欲食，种种皆殊。惟少阳、太阴为近之，而亦有殊者∶经脉目KT KT 属足少阴，而仲景少
阳目眩；经脉飧泄属足厥阴，而仲景三阴俱列。所以然者，经但以阴阳分表里两层，而以身
之前后两侧分为三阴三阳，仲景不但分表里两层，且分表之表为太阳，表之里为少阳，里之
表为太阴，里之里为少阴，里之至里为厥阴，其腑为阳明，义取递进，不取平按。故仅列热
病论六经症于伤寒例，而不即引之以冠六经篇首，别自为说以着，其名同实异也。所以实异
而名仍同者，以太阳等六者，乃古今纪阴阳者之大名，六元以纪天之六气，《难经》以纪岁
之六节，《脉经》卷五扁鹊法以纪一日之六候、卷十手捡图以纪诊法之六部，经筋以纪筋，
皮
部以纪络，若经脉则以纪荣卫，而仲景因以纪表里，其义一也。欲穷《伤寒》六经症者，勿
缠合《灵》、《素》以乱之。
《伤寒论》中列出的六经，与《素问·热病论》中的说法不同。《热病论》是根据气运行的脉络来论述的，所以它描述的病症，与《灵枢·经脉篇》的含义相吻合。《伤寒论》则是根据邪气入侵的次序来论述的，所以它描述的病症，与《灵枢·经脉篇》的含义不相吻合。
在经脉理论中，三阳经（太阳、阳明、少阳）都有头痛的症状，只有阳明经开始有恶寒的表现，而张仲景却将头痛都归入太阳病，反而以胃家实作为正阳明的特征；经脉理论中嗜睡属于足太阴脾经的病证，而张仲景却说少阴病表现为想睡觉；经脉理论中口渴想喝水、饥饿却不能进食，属于足少阴肾经的病证，而张仲景却说厥阴病表现为消渴（极度口渴），喝下去不想吃东西，种种情况都大不相同。
只有少阳病和太阴病与经脉理论比较接近，但也有不同之处：经脉理论中眼睛视物模糊（KT KT 指视物不清或目不明）属于足少阴肾经，而张仲景认为少阳病表现为目眩（眼花）；经脉理论中完谷不化的泄泻属于足厥阴肝经，而张仲景将这类症状列在三阴病中。
之所以这样，是因为经脉理论仅仅用阴阳分为表里两层，并以身体前后两侧分为三阴三阳；而张仲景不仅分表里两层，而且将表的表层称为太阳，表的里层称为少阳，里的表层称为太阴，里的里层称为少阴，最深层称为厥阴，其腑为阳明，其义理取法于层层递进，而不取平面对等的排列方式。
因此，张仲景仅列出《热病论》中的六经症状作为伤寒的范例，而没有直接引用它们来作为六经篇的首领，而是另立学说进行阐述，这就是名称相同但实质不同的原因。之所以实质不同而名称仍相同，是因为“太阳”等六个名称，是古今记录阴阳的大名。《素问·天元纪大论》用它来记录天的六气，《难经》用它来记录岁的六节，《脉经》卷五扁鹊法用它来记录一日的六候、卷十手捡图用它来记录诊法的六部，经筋用它来记录筋，皮部用它来记录络，若经脉则用它来记录营卫，而张仲景借此来记录表里关系，其道理是一致的。
The Six Channels (Liu Jing) listed in the *Shanghan Lun* (Treatise on Cold Damage) differ from those in the *Suwen: Re Bing Lun* (Plain Questions: Treatise on Febrile Diseases). The *Re Bing Lun* is based on the meridians through which Qi circulates; therefore, the symptoms it describes align with the principles of the *Lingshu: Jing Mai Pian* (Spiritual Pivot: Chapter on Meridians). In contrast, the *Shanghan Lun* is based on the sequence of pathogenic invasion; consequently, the symptoms it describes do not align with the principles of the *Lingshu: Jing Mai Pian*.
According to meridian theory, all three Yang channels (Taiyang, Yangming, Shaoyang) present with headache. Only Yangming begins with aversion to cold. However, Zhang Zhongjing includes these in Taiyang disease and defines Zheng Yangming (True Yangming) by "stomach excess" (Wei Shi - accumulation of heat and dryness in the stomach/intestines). Meridian theory states that lethargy belongs to the Foot-Taiyin Spleen channel, whereas Zhang Zhongjing states that Shaoyin disease manifests as a desire to sleep. Meridian theory attributes thirst with desire to drink, and hunger without ability to eat, to the Foot-Shaoyin Kidney channel, whereas Zhang Zhongjing associates Xiao Ke (Wasting-Thirst/Extreme Thirst) and drinking without desire to eat with Jueyin disease. Such discrepancies are numerous.
Only Shaoyang and Taiyin are relatively close to meridian theory, yet even they differ: Meridian theory links visual impairment (mu bu ming) to the Foot-Shaoyin Kidney channel, while Zhang Zhongjing associates dizziness/blurred vision (mu xuan) with Shaoyang disease. Meridian theory links undigested food in stool (sun xie) to the Foot-Jueyin Liver channel, whereas Zhang Zhongjing categorizes such symptoms under the Three Yin diseases.
The reason for this is that meridian theory divides Yin and Yang merely into two layers of exterior and interior, and further divides them into Three Yin and Three Yang based on the anterior and posterior aspects of the body. Zhang Zhongjing, however, not only divides them into exterior and interior layers but also subdivides the exterior's exterior as Taiyang, the exterior's interior as Shaoyang, the interior's exterior as Taiyin, the interior's interior as Shaoyin, and the deepest interior as Jueyin, with its associated Fu organ being Yangming. His theoretical approach emphasizes progressive depth rather than flat, parallel classification.
Therefore, he lists the Six Channel symptoms from the *Re Bing Lun* only as examples for Shanghan, without directly citing them to head the chapters of the Six Channels. He establishes his own distinct theory because, although the names are the same, the substance differs. The reason the substance differs while the names remain the same is that "Taiyang," etc., are grand terms used since ancient times to record Yin and Yang. The *Suwen: Tian Yuan Ji Da Lun* uses them to record the Six Qi of Heaven; the *Nanjing* uses them to record the Six Jie (solar terms/phases) of the year; the *Maijing* (Pulse Classic), Vol. 5 (Bian Que’s Method) uses them to record the six pulses of a day, and Vol. 10 (Hand Inspection Diagram) uses them to record the six positions of pulse diagnosis; Jing Jin (Sinew Channels) use them to record sinews; Pi Bu (Skin Regions) use them to record collaterals; and Jing Mai (Meridians) use them to record Ying and Wei (Nutritive and Defensive Qi). Zhang Zhongjing adopts these terms to record the relationship between Exterior and Interior, sharing the same underlying logic.
Those who wish to thoroughly understand the Six Channel symptoms of the *Shanghan Lun* should not entangle themselves with the *Lingshu* and *Suwen*, lest they cause confusion.