向谓伤寒无补法者，盖伤寒时疫，均是客邪，然伤于寒者，不过风寒，乃天地之
正气，尚嫌其填实而不可补。今感疫气者，乃天地之毒瓦斯，补之则壅裹其毒，邪火愈炽，是以
误补之，为害尤甚于伤寒，此言其常也。及言其变，然又有应补者，或日久失下，形神几脱
，或久病先亏，或先受大劳，或老人枯竭，皆当补泻兼施。设独行而增虚证者，宜急峻补
（虚证散在诸篇，此不再赘），补之虚证稍退，切忌再补（详见前虚后
下后虚证不见，乃臆度其虚，辄用补剂，法所大忌。凡用补剂，本日不见佳处，即非应补。
盖人参为益元气之极品，开胃气之神丹，下咽之后，其效立见。若用参之后，元气不回，胃
气
不转者，勿谓人参之功不捷，盖因投之不当耳，急宜另作主张，若恣意投之，必加变证，如
加而更投之者死。
伤寒阴阳二证，方书皆以对待言之。凡论阳证，即继之阴证，读者以为阴阳二证
世间均有之病，所以临诊之际，先将阴阳二证在于胸次，往来惆HT ，最易牵入误揣。甚有不辨脉
证，但窥其人多蓄少艾，或适在妓家，或房事后得病，或病适至行房，医问及此，便疑为阴
证。殊不知病之将至，虽僧尼寡妇，室女童男，旷夫阉宦，病势不可遏，与房欲何与焉？即便
多蓄少艾，频宿娼妓，房事后适病，病适至行房，此际偶值病邪发行膜原，气壅火郁，未免
发
热，到底终是阳证，与阴证何与焉？况又不知阴证实乃世间非常有之证，而阳证
似阴者何日无之？
究其所以然者，盖不论伤寒温疫传入胃家，阳气内郁，不能外布，即便四逆，所谓阳厥是
也。又曰，厥微热亦微，厥深热亦深。其厥深者，甚至冷过肘膝，脉沉而微，剧则通身冰冷
，脉微欲绝。虽有轻重之分，总之为阳厥。因其触目皆是，苟不得其要领，于是误认者
良多
，况且温疫每类伤寒，又不得要领，最易混淆。夫温疫热病也，从无感寒，阴自何来？一也
；治温疫数百人，才遇二、三正伤寒，二也；及治正伤寒数百人，才遇二、三真阴证，三也
。前后统论，苟非历治多人，焉能一见？阴证岂世间常有之病耶？观今伤寒科盛行之医，历
数年间，或者得遇一真阴证者有之，又何必才见伤寒，便疑阴证，况多温疫，又非伤寒者乎？
过去常说伤寒没有补法，这是因为伤寒和时疫都是外来的邪气。然而，感受寒邪的，不过是风寒之气，这是天地间的正气，尚且担心其导致体内壅滞充实而不能使用补法。如今感受疫气的，是天地间的毒瓦斯（致病秽浊之气），如果误用补法，则会壅塞包裹住毒邪，使邪火更加炽盛，因此误用补法造成的危害比伤寒更为严重，这是说通常的情况。至于谈到变化的情况，那么又有应当使用补法的，比如病程日久未能及时攻下，导致形体和精神几乎脱失；或者久病之后身体先已亏损；或者先前遭受过大的劳累；或者老人身体枯竭，这些情况都应当补泻兼施。如果单纯使用补法反而增加虚证症状的，应当紧急峻补（虚证的表现散见于各篇中，此处不再赘述）。补法使用后，如果虚证症状稍退，就切忌再次进补（详见前文：后下后出现虚证不见，乃是臆测患者有虚证，就随意使用补剂，这是治法中的大忌。凡是使用补剂，当天如果不见好转，就不是应当补的情况。因为人参是补益元气的极品，开胃气的灵丹妙药，服下之后，效果立竿见影。如果使用人参之后，元气不能恢复，胃气不能转运，不要说是人参的功效不敏捷，而是因为投药不当。此时应当立即改变治疗方案，如果肆意继续投用，必然加重变证，如果加重了还继续投用，病人就会死亡。
伤寒的阴证和阳证，医书中都是以相对的概念来论述的。凡是论述阳证，紧接着就会论述阴证，读者便以为阴阳二证是世间都存在的疾病。所以在临诊之际，心中先存有阴阳二证的观念，往来犹豫不定，最容易陷入错误的揣测。甚至有的人不辨别脉象和症状，只是看到这个人家里蓄养了很多年轻女子，或者刚好在妓院，或者房事后得了病，或者生病时恰好进行房事，医生问到这些情况，就怀疑是阴证。殊不知疾病将要发作时，即使是僧尼寡妇、处女童男、单身男子或宦官，病势不可遏制，这与房事欲望有什么关系呢？即便家中多蓄年轻女子，频繁宿于娼妓家，房事后恰好生病，生病时恰好行房，此刻偶然正值病邪从膜原（半表半里之部位）发出，气机壅滞，火邪郁结，难免会出现发热，但归根结底仍然是阳证，与阴证有什么关系呢？况且又不知道阴证实乃世间非常罕见的证候，而表现为类似阴证的阳证何日没有呢？
探究其所以然的原因，大概不论伤寒还是温疫传入胃家，阳气在内郁结，不能向外布散，即便出现四肢逆冷，这就是所谓的“阳厥”（热深厥亦深）。又说，厥冷轻微则发热也轻微，厥冷深重则发热也深重。那些厥冷深重的，甚至冷过肘部和膝盖，脉象沉而微弱，严重的则全身冰冷，脉微欲绝。虽然有轻重的区别，总归属于阳厥。因为这些现象触目皆是，如果不能抓住要领，于是误认的人很多。况且温疫每类同于伤寒，又不得要领，最容易混淆。夫温疫是热病，从未有感受寒邪的，阴证从何而来？这是一点；治疗温疫数百人，才遇到两三个真正患伤寒的，这是第二点；等到治疗真正伤寒数百人，才遇到两三个真正的阴证，这是第三点。前后综合论述，如果不是亲自治疗过很多人，怎么能一眼看出？阴证难道是世间常有的疾病吗？观察当今盛行于世的伤寒科医生，历经数年之间，或许能遇到一个真阴证的，又何必刚见到伤寒症状，就怀疑是阴证，何况多是温疫，又不是伤寒的呢？
It was previously said that there is no tonification method for Shanghan (Cold Damage), because both Shanghan and seasonal epidemics are external pathogens. However, contracting cold pathogen involves only Wind-Cold, which is the upright Qi of Heaven and Earth; even so, one might still worry about it causing fullness and stagnation, making tonification inadvisable. Now, contracting epidemic Qi involves the toxic miasma of Heaven and Earth. If tonification is used, it will obstruct and envelop the toxin, causing the evil fire to burn more fiercely. Therefore, erroneous tonification causes harm even greater than in Shanghan; this describes the general rule. Regarding variations, however, there are cases requiring tonification: for instance, if the disease has persisted for a long time without timely purgation, leading to near-collapse of form and spirit; or if the body was already deficient due to prolonged illness; or if there was prior severe exertion; or if an elderly person is depleted. In all these cases, tonification and purgation should be combined. If using tonification alone exacerbates deficiency symptoms, urgent and potent tonification is indicated (Deficiency syndromes are discussed in various chapters and will not be repeated here). After tonification, if deficiency symptoms subside slightly, one must strictly avoid further tonification (See earlier text: If deficiency symptoms disappear after purgation, presuming deficiency and arbitrarily using tonics is a major contraindication. Whenever tonics are used, if there is no improvement on the same day, it indicates that tonification is not indicated. Ginseng is the supreme agent for benefiting Yuan Qi and the miraculous elixir for opening Stomach Qi; its effect is immediate upon ingestion. If after administering Ginseng, Yuan Qi does not return and Stomach Qi does not rotate, do not claim that Ginseng lacks efficacy; rather, it is due to improper administration. One must immediately change the strategy. Indiscriminate continued use will inevitably worsen complications; if complications worsen and one continues to administer it, death will ensue.
The Yin and Yang syndromes of Shanghan are discussed in medical texts as opposing concepts. Whenever Yang syndromes are discussed, Yin syndromes follow. Readers may assume that both Yin and Yang syndromes exist universally in the world. Consequently, during clinical practice, holding these two syndromes in mind leads to hesitation and uncertainty, easily resulting in misdiagnosis. Some physicians, without distinguishing pulse and symptoms, merely observe that a patient keeps many young women, visits brothels, falls ill after sexual intercourse, or engages in intercourse while sick. Upon hearing such details, they suspect a Yin syndrome. Little do they know that when a disease is about to manifest, whether for monks, nuns, widows, virgins, bachelors, or eunuchs, the pathological momentum is irresistible and has nothing to do with sexual desire. Even if a man keeps many young women, frequents prostitutes, falls ill after sex, or has sex while ill, at this moment, if the epidemic pathogen erupts from the Membrane Source (a location between the exterior and interior), causing Qi stagnation and Fire depression, fever may inevitably occur. Ultimately, it remains a Yang syndrome, what relation does it have to a Yin syndrome? Moreover, they fail to realize that true Yin syndromes are extremely rare in the world, whereas Yang syndromes mimicking Yin are common every day.
To explore the reason behind this: regardless of whether Shanghan or Wen Yi (Warm Epidemic) transmits to the Stomach house, internal obstruction of Yang Qi prevents it from distributing outward, leading to cold extremities, known as "Yang Jue" (Yang Reversal/Cold Extremities due to Heat). It is also said: slight reversal implies slight heat; deep reversal implies deep heat. In cases of deep reversal, cold may extend beyond elbows and knees, with a deep and faint pulse; in severe cases, the whole body becomes ice-cold, and the pulse is faint and nearly imperceptible. Despite differences in severity, all belong to Yang Jue. Since these phenomena are ubiquitous, failing to grasp the essence leads to numerous misidentifications. Furthermore, since Wen Yi often resembles Shanghan, and lacking the essential understanding, confusion is easy. Wen Yi is a heat disease; it never results from contracting cold, so where would Yin come from? This is point one. Having treated hundreds of Wen Yi patients, only two or three cases of true Shanghan were encountered; this is point two. Having treated hundreds of true Shanghan patients, only two or three true Yin syndromes were encountered; this is point three. Synthesizing past experiences, unless one has treated many people, how could one recognize it at a glance? Is Yin syndrome a common disease in the world? Observing contemporary physicians specializing in Shanghan, over several years, perhaps one encounters a true Yin syndrome. Why suspect Yin syndrome merely upon seeing Shanghan symptoms, especially when most cases are Wen Yi, not Shanghan?