赵嗣真曰∶详仲景发汗汤剂，各轻重不同。如麻黄汤、桂枝汤、青龙、各半、
越婢等汤，各有差等。至于少阴发汗二汤，虽同用麻黄、附子，亦有加减轻重之别。故以加细辛为
重，加甘草为轻，辛散甘缓之义也。其第一证以少阴本无热，今发热，故曰反也。其发热，为邪在
表而当汗，又兼脉沉属阴而当温，故以附子温经，麻黄散寒，而热须汗解，故加细辛，是汗剂之重
者。第二证既无里寒之可温，又无里热之可下，求其所以用麻黄、附子之义，则是脉亦沉，方可名
曰少阴病，身亦发热，方可行发表药。又得之二三日，病尚浅，比之前证亦稍轻，故不重言脉证而
但曰微发汗，所以去细辛，加甘草，是汗剂之轻者。使脉不沉，身不热，又无他证，是无病患也，
又何药焉？仲景本分作两证，以别汗剂之轻重。《活人书》却与第二证中除去无证两字，改作尝见。
少阴热无阳证者，如经云心中烦不得眠，或咽疮声不出者，或咳而呕渴，或口燥咽干，或腹胀不大
便，数证皆是也，夫岂麻黄附子甘草汤发汗剂所可治耶。抑又有闻焉，麻黄附子细辛汤为治少阴病
之脉沉，反发热者用也，而仲景又有四逆汤治太阳病之发热，反脉沉者，均为之反也。仲景云∶病
发
热头痛，脉反沉，若不瘥，身体疼痛者，当救其里，宜四逆汤。此证出太阳篇。又云∶少阴病，始
得之，反发热，脉沉者，麻黄附子细辛汤。此证出少阴篇。切详太阳病，发热头痛，法当脉浮，今
反沉；少阴脉沉，法当无热，今反热，仲景于此两证各言反者，谓反常也。盖太阳病脉似少阴，少
阴病证似太阳，所以谓之反，而治之当异也。今深究其旨，均是脉沉发热，以其有头痛，故谓太阳
病。阳证当浮脉，今反不能浮者，以里虚久寒，正气衰微所致。又身体疼痛，故宜救里，使正气内
强，逼邪外出，而干姜、生附子亦能出汗而解。假使里不虚寒，则当见脉浮，而正属太阳麻黄证也。
均是脉沉发热，以其无头疼，故名少阴病。阴病当无热，今反热，寒邪在表，未传在里，但皮肤腠
理郁闭为热，如在里无热，故用麻黄、细辛以发表间之热，附子以温少阴之经。假使寒邪入里，则
外必无热，当见吐痢厥逆等证，而正属少阴四逆汤证也。由此观之，表邪浮浅，发热之反犹轻，正
气衰微，脉沉之反为重。此四逆为剂，不为不重于麻黄附子细辛汤也。又可见熟附配麻黄，发中有
补，生附配干姜，补中有发，仲景之旨微矣。嗟夫，常病用常法，夫谁不知。设有证变者，或脉变
者，往往疑似参差，夫欲以常法例治之，惑矣。如仲景所论太阳少阴两证，脉沉发热虽同，而受病
与用药自别。此实证治之奇异，医法之玄微，故并及之耳。
赵嗣真说：详细考察张仲景的发汗汤剂，其轻重程度各不相同。例如麻黄汤、桂枝汤、大青龙汤、小青龙汤（注：原文“青龙”通常指大小青龙，此处结合语境及后文“各半”，泛指此类方剂）、桂枝麻黄各半汤、越婢汤等，各有等级差别。至于少阴病发汗的两首方剂，虽然都使用了麻黄和附子，但在剂量加减和轻重上也有区别。因此，加入细辛的为重证，加入甘草的为轻证，这体现了细辛辛散、甘草甘缓的药理意义。
第一个证候，因为少阴本无热象，现在出现发热，所以称为“反”。这种发热，是因为邪气在表而应当发汗，同时又兼有脉沉属于阴证而应当温补，所以用附子温通经脉，麻黄发散寒邪，而热邪需要通过发汗来解除，因此加入细辛，这是发汗剂中作用较强的方子。
第二个证候，既然没有里寒需要温补，也没有里热需要攻下，探究其中使用麻黄、附子的意义，则是脉象依然沉，才能称之为少阴病；身体依然发热，才能使用发表药。而且患病才两三天，病势尚浅，比前一个证候也稍轻一些，所以不再着重描述脉证，只说“微发汗”，因此去掉细辛，加入甘草，这是发汗剂中作用较弱的方子。如果脉不沉，身不热，又没有其他症状，那就是没有病患了，还用得着什么药呢？
张仲景原本将这两种情况分为两个证候，以区分发汗剂的轻重。《活人书》却在第二个证候中去掉了“无证”二字，改为“尝见”。少阴病如果有热象而没有阳证表现的情况，如经文所说心中烦闷不得安卧，或者咽喉生疮声音不出，或者咳嗽呕吐口渴，或者口燥咽干，或者腹胀不大便，这些数种证候都是如此，这难道是麻黄附子甘草汤这种发汗剂所能治疗的吗？
另外我还听说，麻黄附子细辛汤是用于治疗少阴病脉沉、反而发热的；而张仲景又有四逆汤用于治疗太阳病发热、反而脉沉的情况，这两种情况都称为“反”。张仲景说：病人发病发热头痛，脉象反而沉，如果不好转，身体疼痛的，应当救其里，适宜用四逆汤。这个证候出自太阳篇。又说：少阴病，刚开始得病，反而发热，脉象沉的，用麻黄附子细辛汤。这个证候出自少阴篇。仔细推究太阳病发热头痛，按法应当脉浮，现在反而沉；少阴病脉沉，按法应当无热，现在反而热，张仲景在这两个证候中都提到“反”，是指反常。大概太阳病的脉象像少阴病，少阴病的证候像太阳病，所以称为“反”，而治疗方法应当不同。
现在深入探究其旨意，同样是脉沉发热，因为有头痛，所以称为太阳病。阳证应当见浮脉，现在反而不能浮，是因为里虚久寒，正气衰微所致。又有身体疼痛，所以适宜救里，使正气内强，逼迫邪气外出，而生附子和干姜也能通过出汗而解表。假如里没有虚寒，则应当见到脉浮，那正属于太阳病的麻黄汤证。
同样是脉沉发热，因为没有头痛，所以称为少阴病。阴病应当无热，现在反而热，是因为寒邪在表，未传入里，只是皮肤腠理郁闭而产生热象，如果在里没有热，所以用麻黄、细辛来发表间的热，用附子来温少阴的经脉。假如寒邪入里，则外面必然无热，应当见到呕吐、下痢、四肢厥逆等证候，那正属于少阴病的四逆汤证。
由此看来，表邪浮浅，发热的“反”还较轻；正气衰微，脉沉的“反”则较重。这四逆汤作为方剂，不能说比麻黄附子细辛汤轻。又可以看出，熟附子配麻黄，发汗中有补益作用；生附子配干姜，补益中有发汗作用，张仲景的旨意真是精微啊。唉！常规疾病用常规方法治疗，谁不知道呢？如果遇到证候变化、或者脉象变化的情况，往往疑似参差，想要用常规方法来治疗，就迷惑了。如张仲景所论述的太阳、少阴两个证候，脉沉发热虽然相同，但受病原因与用药自然不同。这是实证治疗的奇异之处，医法的玄妙细微，所以一并提及罢了。
Zhao Sizhen stated: A detailed examination of Zhang Zhongjing's sweating-inducing decoctions reveals varying degrees of potency. For instance, the Ma Huang Tang (Ephedra Decoction), Gui Zhi Tang (Cinnamon Twig Decoction), Qing Long Tangs (Green Dragon Decoctions), Ge Ban Tang (Half-Combined Decoction), and Yue Bi Tang (Yuebi Decoction) each possess distinct gradations. Regarding the two sweating-inducing formulas for Shaoyin disease (Disease of the Lesser Yin), although both utilize Ma Huang (Ephedrae Herba) and Fu Zi (Aconiti Lateralis Radix Praeparata), there are differences in dosage adjustments and intensity. Thus, the addition of Xi Xin (Asari Radix et Rhizoma) denotes a heavier formula, while the addition of Gan Cao (Glycyrrhizae Radix et Rhizoma) denotes a lighter one, reflecting the principles of Xi Xin's acrid dispersal and Gan Cao's sweet moderation.
In the first syndrome, since Shaoyin inherently lacks heat manifestations, the emergence of fever is termed "counter" (fan). This fever arises because the pathogen is in the exterior, requiring diaphoresis, yet the deep pulse indicates an interior yin condition requiring warming. Therefore, Fu Zi is used to warm the meridians, Ma Huang to disperse cold, and Xi Xin is added to facilitate the resolution of heat through sweating; this constitutes a potent sweating agent.
In the second syndrome, since there is no interior cold requiring warming nor interior heat requiring purging, the rationale for using Ma Huang and Fu Zi is that the pulse remains deep, qualifying it as Shaoyin disease, and the body retains fever, allowing for exterior-releasing medication. Furthermore, having contracted the disease only two or three days prior, the pathology is still shallow and slightly milder than the previous syndrome. Consequently, rather than emphasizing specific pulse and symptom details, it merely states "mild diaphoresis." Hence, Xi Xin is removed and Gan Cao is added, constituting a mild sweating agent. If the pulse were not deep, the body not feverish, and no other symptoms present, there would be no patient, and thus no need for medication.
Zhang Zhongjing originally divided these into two syndromes to distinguish the heaviness and lightness of sweating agents. However, *Ren Shu* (The Book of Human Life) removed the phrase "no [other] symptoms" from the second syndrome and changed it to "once observed." In Shaoyin disease with heat but without yang syndromes, such as described in the classics: mental restlessness with inability to sleep, throat sores with loss of voice, cough with vomiting and thirst, dry mouth and throat, abdominal distension with constipation—these numerous syndromes certainly cannot be treated by Ma Huang Fu Zi Gan Cao Tang, a sweating agent.
Moreover, I have heard that Ma Huang Fu Zi Xi Xin Tang is used for Shaoyin disease presenting with a deep pulse and counter fever. Conversely, Zhang Zhongjing employed Si Ni Tang (Frigid Extremities Decoction) for Taiyang disease (Disease of the Greater Yang) presenting with fever and a counter-deep pulse. Both scenarios are termed "counter." Zhang Zhongjing stated: "When a disease begins with fever and headache, and the pulse is counter-deep, if it does not improve, and body pain persists, one should rescue the interior,适宜 Si Ni Tang." This syndrome appears in the Taiyang chapter. He also stated: "In Shaoyin disease, upon initial onset, if there is counter fever and a deep pulse, use Ma Huang Fu Zi Xi Xin Tang." This syndrome appears in the Shaoyin chapter. Carefully analyzing the Taiyang disease with fever and headache, the pulse should theoretically be floating; the fact that it is counter-deep contrasts with the Shaoyin disease where a deep pulse should theoretically lack heat, yet here there is counter-heat. Zhang Zhongjing uses "counter" in both cases to denote abnormality. Essentially, the Taiyang pulse resembles Shaoyin, and the Shaoyin syndrome resembles Taiyang; hence they are called "counter," and their treatments must differ.
Upon deep investigation, although both present with a deep pulse and fever, the presence of headache classifies it as Taiyang disease. Yang syndromes should exhibit a floating pulse; the failure to float is due to chronic interior deficiency-cold and the decline of righteous qi. With accompanying body pain, rescuing the interior is appropriate to strengthen internal righteousness, forcing pathogens outward; indeed, Gan Jiang (Zingiberis Rhizoma) and Sheng Fu Zi (Aconiti Radix) can also induce sweating to resolve the condition. Had the interior not been deficient and cold, a floating pulse would be seen, fitting the Taiyang Ma Huang Tang syndrome.
Similarly, although both present with a deep pulse and fever, the absence of headache classifies it as Shaoyin disease. Yin syndromes should lack heat; the presence of counter-heat indicates cold pathogens in the exterior that have not transmitted inward, causing heat via stagnation of skin and pores. Since there is no heat in the interior, Ma Huang and Xi Xin are used to release exterior heat, while Fu Zi warms the Shaoyin meridians. Had the cold pathogens entered the interior, there would be no exterior heat, and symptoms like vomiting, diarrhea, and cold extremities would appear, fitting the Shaoyin Si Ni Tang syndrome.
From this perspective, superficial exterior pathogens with counter-fever represent a milder deviation, whereas the decline of righteous qi with a counter-deep pulse represents a more severe deviation. Thus, Si Ni Tang is not inferior in weight to Ma Huang Fu Zi Xi Xin Tang. It further demonstrates that prepared Fu Zi paired with Ma Huang provides tonification within dispersion, while raw Fu Zi paired with Gan Jiang provides dispersion within tonification. The subtlety of Zhang Zhongjing's intent is profound. Alas, treating common diseases with standard methods is known to all. However, when syndromes or pulses change, ambiguity often arises; attempting to apply standard methods in such cases leads to confusion. As discussed by Zhang Zhongjing regarding Taiyang and Shaoyin syndromes, although deep pulse and fever are identical, the etiology and treatment differ. These anomalies in treating excess syndromes reveal the profound subtleties of medical practice, which is why they are mentioned together.