夫伤寒言证不言病者，厥有旨哉！证之一字，有明证、见证、对证之义存焉。如妇以证奸，赃
以证盗，刃以证杀，不容辞而无所逃其情矣。且人之心、肝、脾、肺、肾在人身中，藏而不见者。
若夫口、鼻、舌、耳、目则露而共见者也，五脏受病，人焉能知之？盖有诸中，必形诸外。肝有病
则目不能视，心有病则舌不能言，脾有病则口不知味，肺有病则鼻不闻香，肾有病则耳不听声，以
此言之，则证亦亲切矣。况风寒之中人，受之必有经络部分，一或伤之，本经之证见矣。更能以脉
参之，庶无差忒矣。吾故曰伤寒言证耳。如太阳伤寒，为表之表，其经行身之后，从头下至足，则
头项痛，腰脊强之证见于项背也。恶寒证亦在表。盖伤寒恶寒，伤风恶风。太阳为寒水之经，凡见
恶寒便为在表，最为的当。传至阳明之经，则不恶寒，便不宜发表。如有一毫头痛恶寒，尚在太阳，
便是表证未罢，不可攻里。故戒
曰∶发表不开，不可攻里。此事不明，杀人至速。又曰∶凡呕者，不可下。经曰∶呕多，虽有阳明
证，不可攻，攻之为逆。心下硬者，不可下。切宜仔细。阳明经为表之里，其经行身之前，夹鼻络
于目，故目痛，鼻干不眠。少阳经行身之侧，为半表半里，始于目锐 ，循胁络于耳，交于膻中两
乳正中，故胸胁痛而耳聋。此三经病之易见，盖如此盒饭诊脉以参之。若太阳经则有二证，一为伤
寒，一为伤风。脉浮紧，恶寒无汗，为伤寒。脉浮为在表，紧为有寒。表受寒邪而未入里，宜麻黄
汤辛甘温之剂以发之。（冬用正药，三时用羌活汤。）此皆有恶寒头痛，为在太阳之表，尚未传入
里，通宜发而散之。若在阳明则脉微洪而长，按之皮肤之下，肌肉之间，此非表非里而为在经。或
渴，用葛根汤以解肌。少阳经则脉弦数，不浮不沉，在乎半表半里之间，宜小柴胡汤以和之。（有
加减法。）此二经者，不从标本从乎中治也。中之下即肌肉之下，筋骨之间也。脉按之沉数有力，
则为热入阳明之本，宜大柴胡汤、三承气汤，看燥结微甚而下之。前之所云恶寒头痛俱通治。脉不
浮而沉实有力，此为
表证罢而里证具，宜泄去其胃中实热而愈矣。若老弱产虚，或带表证必须下者，皆用大柴胡汤。脉
若沉迟，微弱无力，则又为阴证也，宜温而不宜下也，谨之。
伤寒学说中只谈“证”而不谈“病”，其中确实蕴含着深刻的用意！“证”这个字，包含了明辨证据、观察表现、针对症状（对证）的含义。就像妇女用证据来证实奸情，用赃物来证实盗窃，用刀器来证实杀人一样，无法抵赖且无处逃避真相。况且人的心、肝、脾、肺、肾在人体内部，隐藏而不显露。至于口、鼻、舌、耳、目则是外露且大家都能看见的。五脏受到疾病侵害，人怎么能直接知道呢？大概是因为内在有病变，必然会在外部表现出来。肝脏有病则眼睛不能视物，心脏有病则舌头不能言语，脾脏有病则嘴巴不知道味道，肺脏有病则鼻子闻不到香气，肾脏有病则耳朵听不到声音。从这些方面来说，“证”也就显得非常切近重要了。
何况风寒邪气侵袭人体，受邪必定沿着经络部位进行，一旦受伤，本经的症状就会显现出来。如果能再结合脉象来参详，就几乎没有差错失误了。所以我所以说伤寒只谈“证”。比如太阳伤寒，属于表证的表层，其经脉行于身体后方，从头向下直到足部，所以头项疼痛、腰脊强直的症状出现在项背部。恶寒的症状也在体表。因为伤寒表现为怕冷，伤风表现为怕风。太阳经是寒水之经，凡是见到恶寒就说明病在表，这是最为确切的。如果病邪传至阳明经，就不再恶寒，此时就不宜使用发汗解表的方法。如果还有一点点头痛恶寒，说明病邪仍在太阳经，这就是表证未解除，不可攻逐里实。所以告诫说：表证未解不可攻里。如果不明白这个道理，杀人非常快。又说：凡是呕吐的，不可使用泻下法。经文说：呕吐多者，即使有阳明证，也不可攻下，攻下就是逆治。心下硬满的，不可泻下。务必仔细辨别。
阳明经是表的里层，其经脉行于身体前方，夹鼻络于目，所以出现眼睛痛、鼻子干、失眠的症状。少阳经行于身体侧面，属于半表半里，起始于目外角，沿胁肋络于耳，交会于膻中及两乳正中，所以出现胸胁疼痛和耳聋。这三经的疾病容易诊断，大概就是这样。应当诊脉来参详。若太阳经则有两种证候，一种是伤寒，一种是伤风。脉象浮紧，恶寒无汗，属于伤寒。脉浮说明病在表，脉紧说明有寒邪。表受寒邪而未入里，适宜用麻黄汤（Cinnamon Twig, Ephedra and Prepared Rehmannia Decoction）这种辛甘温的方剂来发汗。（冬季用正药，三伏天用羌活汤。）这些都有恶寒头痛，说明病在太阳之表，尚未传入里，通宜发汗散邪。如果在阳明经，则脉象微洪而长，按之在皮肤之下、肌肉之间，这既非纯表也非纯里，而是病在经。或者口渴，用葛根汤（Pueraria Root Decoction）来解肌。少阳经则脉象弦数，不浮不沉，处于半表半里之间，适宜用小柴胡汤（Pinellia Decoction）来和解。（有加减法。）这两经的病，不从标本而从乎中治。中之下即肌肉之下、筋骨之间。脉象按之沉数有力，则为热入阳明之本，适宜用大柴胡汤（Bupleurum and Rhubarb Decoction）、三承气汤（Three Chengqi Decoctions），根据燥结的轻重程度来泻下。前面所说的恶寒头痛都通用治法。脉象不浮而沉实有力，这说明表证已罢而里证具备，适宜泄去胃中的实热而痊愈。如果是老弱、产后虚弱，或者带有表证必须下法的，都用大柴胡汤。脉象若沉迟，微弱无力，则又是阴证，适宜温补而不适宜泻下，务必谨慎。
The fact that the Treatise on Cold Damage (Shanghan Lun) discusses "syndromes" (Zheng, clinical manifestations/syndromes) rather than "diseases" (Bing, diseases) contains profound significance. The term "syndrome" implies clear evidence, observed manifestations, and targeted symptoms. Just as a woman uses evidence to prove adultery, stolen goods to prove theft, and a weapon to prove murder, leaving no room for denial or escape from the truth. Moreover, the Heart, Liver, Spleen, Lung, and Kidney are hidden within the body and not visible. In contrast, the mouth, nose, tongue, ears, and eyes are exposed and visible to all. How can one know if the Zang organs are diseased? Generally, internal pathology must manifest externally. If the Liver is diseased, vision is impaired; if the Heart is diseased, speech is affected; if the Spleen is diseased, taste is lost; if the Lung is diseased, smell is diminished; if the Kidney is diseased, hearing is dulled. Thus, syndromes are indeed intimate and significant indicators.
Furthermore, when Wind-Cold pathogens invade the human body, they affect specific meridians and regions. Once injured, the syndromes of the affected meridian appear. By correlating these with pulse diagnosis, errors can be avoided. Hence, I say that in Cold Damage medicine, we discuss syndromes. For instance, Taiyang Cold Damage represents the exterior of the exterior. Its meridian runs along the posterior aspect of the body, from the head down to the feet. Therefore, symptoms such as headache, stiff neck, and stiffness in the lower back and spine appear in the nape and back. Aversion to cold is also an exterior symptom. Cold damage causes aversion to cold, while wind strike causes aversion to wind. The Taiyang meridian is associated with Cold Water; thus, any presence of aversion to cold indicates an exterior syndrome, which is most accurate. If the pathogen transmits to the Yangming meridian, aversion to cold ceases, and exterior-releasing methods should not be used. If there is even slight headache and aversion to cold, the pathogen remains in Taiyang, meaning the exterior syndrome has not resolved, and interior purgation is contraindicated. Therefore, it is warned: "If the exterior is not released, do not purge the interior." Failure to understand this leads to rapid death. It is also stated: "In cases of vomiting, do not use purgatives." The Classic says: "With frequent vomiting, even if Yangming syndromes are present, do not attack/purge; doing so constitutes reverse treatment." If there is hardness below the heart, do not purge. Careful attention is required.
The Yangming meridian is the interior of the exterior. It runs along the anterior aspect of the body, connecting the nose and eyes. Thus, eye pain, dry nose, and insomnia occur. The Shaoyang meridian runs along the lateral aspect of the body, representing the half-exterior, half-interior stage. It starts at the outer canthus, follows the hypochondrium, connects to the ear, and intersects at the Danzhong (Conception Vessel 17) and between the breasts. Thus, chest and hypochondriac pain and deafness occur. These three meridians' diseases are easily diagnosed in this manner, supplemented by pulse examination.
Taiyang disease has two types: Cold Damage and Wind Strike. Pulse floating and tight, with aversion to cold and absence of sweating, indicates Cold Damage. Floating pulse indicates the exterior; tight pulse indicates Cold. Since the exterior is invaded by Cold but has not entered the interior, Xin-Gan-Warm formulas like Mahuang Tang (Ephedra, Cinnamon Twig, and Apricot Seed Decoction) should be used to induce sweating. (In winter, use the standard formula; in summer, use Qianghuo Tang.) These present with aversion to cold and headache, indicating Taiyang exterior syndrome not yet transmitted inward, requiring dispersal through sweating. If in Yangming, the pulse is slightly surging and long, felt beneath the skin and within the muscles, indicating neither pure exterior nor pure interior, but involvement of the meridian. If thirst is present, Gegen Tang (Kudzu Root Decoction) is used to resolve the muscle layer. In Shaoyang, the pulse is wiry and rapid, neither floating nor sunken, situated in the half-exterior, half-interior region. Xiaochaihu Tang (Minor Bupleurum Decoction) is used to harmonize. (There are modification methods.) These two meridians are treated via the middle method, neither following the root nor the branch. The "middle" refers to the area below the muscles and between the sinews and bones. If the pulse is deep, rapid, and forceful upon pressure, it indicates Heat entering the root of Yangming. Dachaihu Tang (Major Bupleurum and Rhubarb Decoction) or the Three Chengqi Decoctions (Three Bowel-Regulating Decoctions) should be used to purge, depending on the severity of dryness and accumulation. The previously mentioned aversion to cold and headache are general treatments. If the pulse is not floating but deep, solid, and forceful, it indicates that the exterior syndrome has resolved and the interior syndrome is established. Purging the excess heat in the Stomach will lead to recovery. For the elderly, weak, postpartum women, or those who must be purged despite having exterior symptoms, Dachaihu Tang is used. If the pulse is deep, slow, weak, and forceless, it indicates a Yin syndrome. Warmth is indicated, not purgation. Caution is essential.