问曰。厥之寒热。何以别之。答曰。仲景言诸四逆厥者不可下。虚家亦然。又曰。厥阴
下之
。其语似涉两歧。然要认明病之来路。彼因四逆而厥。故不可下。此因发热而厥。故应下之
。此中消息。言下本自跃然。再推厥深热深之义。温热病一二日或五六日。沉昏谵妄。手足
厥逆。是热邪入膻之候。膻中属手厥阴是亦厥阴证也。仲景虽未明言。而厥深热深一语。已
包括无遗矣。谁谓温热之法。不可向仲景推寻哉。
仲景六经之法。一经有一经之证。先要分看。分看宜在有字句处精研。而或此经杂彼经
之症。
又要合看。合看全在无字句处善悟。而尤要在于辨似。有阳中之阴。有阴中之阳。有阳中之
阳。有阴中之阴。有阳证似阴。有阴证似阳。有阳证转阴。有阴证转阳。有阳证杂阴。有阴
证杂阳。有阴
阳错杂非细心体认。恶能窥其万一。今人辄畏仲景书难读。而从事于后世之方书。是犹涉海
问津。从仲景伤寒入手。始觉甚难。久之则其易焉者至矣从后世方书入手。始觉甚易。久之则
其难焉者至矣。总之凡病不外此六经。能解仲景六经辨证之法。可以识伤寒。即推此六经辨
证之法。可以识万病。伤寒既了然无遗。于杂证乎何有。此一以贯之之道也。故曰万病莫逃乎伤寒。
问：四肢厥冷的寒证与热证，如何加以辨别？
答：张仲景说，凡是出现四肢逆冷（四逆）和厥逆的病证，不可使用泻下法；体质虚弱的人也是如此。他又说，对于厥阴病误用泻下法……这两句话看似有些矛盾。然而关键在于认清疾病的来路。那些因为阳气衰微导致四肢逆冷而引发厥逆的，所以不可用泻下法；而那些因为体内有实热导致手足厥冷的，所以应当用泻下法。其中的奥妙，在言语之下本就很明显。再推究“厥深热亦深”的含义：温热病在发病一两天或五六天时，出现神志沉昏、胡言乱语、妄动，以及手足逆冷，这是热邪侵入膻中（心包络所在之处）的征象。膻中属于手厥阴经，这也是厥阴证的范畴。张仲景虽然没有明确说明这一点，但“厥深热亦深”这句话已经将其涵盖无遗了。谁说温热病的治法不能向张仲景的理论中去探寻呢？
张仲景的六经辨证体系，每一经都有每一经的证候表现。首先要分开来看，分开看应当在有文字记载的地方精心研究；而对于这一经夹杂另一经症状的情况，又要合起来看。合起来看全在于对没有文字直接说明的地方善于领悟。尤其重要的是要辨别相似的症状。有阳证中的阴证，有阴证中的阳证，有阳证中的阳证，有阴证中的阴证，有阳证看起来像阴证，有阴证看起来像阳证，有阳证转化为阴证，有阴证转化为阳证，有阳证夹杂阴证，有阴证夹杂阳证。如果不是细心体察认识，怎么能窥探到其中万分之一的情形呢？现在的人往往畏惧《伤寒论》难读，而去从事于后世的方书学习。这就像渡海却不去询问渡口在哪里一样。从张仲景的《伤寒论》入手，起初觉得很难，时间久了就觉得它变得非常容易；从后世的方书入手，起初觉得很容易，时间久了就觉得它变得非常困难。总之，所有的疾病不外乎这六经。能够理解张仲景六经辨证的方法，就可以识别伤寒；进而推广这六经辨证的方法，就可以识别各种疾病。既然对伤寒已经了然于心、毫无遗漏，那么对于杂病又会有什么困难呢？这是一以贯之的道理啊。所以说，各种疾病都逃不出伤寒的范畴。
Q: How can one distinguish between cold-type and heat-type Jue (cold extremities)?
A: Zhang Zhongjing stated that for all cases of Si Ni (four limbs becoming cold) and Jue, purgation should not be used; this applies equally to patients with deficient constitutions. He also stated that if Jue Yin disease is treated with purgation... These two statements seem somewhat contradictory at first glance. However, the key lies in clearly identifying the origin of the disease. Those who develop Jue due to cold extremities caused by Yang deficiency should not undergo purgation. Conversely, those whose extremities become cold due to internal excess heat should indeed undergo purgation. The nuance here is self-evident from the context. Furthermore, considering the principle of "the deeper the Jue, the deeper the heat": in warm-heat diseases, if a patient presents with deep lethargy, delirium, manic behavior, and cold extremities on the first or second day, or even after five or six days, this indicates that heat pathogens have entered the Dan Zhong (Pericardium). Since the Pericardium belongs to the Hand Jue Yin meridian, this is also considered a Jue Yin syndrome. Although Zhang Zhongjing did not explicitly state this, the phrase "the deeper the Jue, the deeper the heat" encompasses it entirely. Who says that the methods for treating warm-heat diseases cannot be traced back to Zhang Zhongjing's theories?
The Six Meridians system of Zhang Zhongjing dictates that each meridian has its own specific syndromes. One must first analyze them separately; separate analysis requires careful study of the explicit textual descriptions. However, when symptoms of one meridian are mixed with another, they must be analyzed holistically; holistic analysis relies on keen insight into what is not explicitly written. Most importantly, one must differentiate between similar presentations. There are Yin within Yang, Yang within Yin, Yang within Yang, and Yin within Yin. There are Yang syndromes resembling Yin, Yin syndromes resembling Yang, Yang syndromes transforming into Yin, Yin syndromes transforming into Yang, Yang syndromes complicated by Yin, and Yin syndromes complicated by Yang. Without careful observation and understanding, how could one possibly grasp even a fraction of these complexities? Modern practitioners often fear that the *Shanghan Lun* is too difficult to read and instead turn to later medical formularies. This is like attempting to cross a sea without asking for the ferry crossing. Starting with Zhang Zhongjing’s *Shanghan Lun*, one may initially find it difficult, but over time, it becomes increasingly easy. Starting with later formularies, one may initially find it easy, but over time, it becomes increasingly difficult. In summary, all diseases fall within the scope of these Six Meridians. If one can understand Zhang Zhongjing’s method of Six Meridians differentiation, one can identify Shanghan (Cold Damage); extending this method of differentiation allows one to identify myriad other diseases. Once Shanghan is thoroughly understood without omission, what difficulty would there be in handling miscellaneous diseases? This is the principle of consistency running through everything. Therefore, it is said that all diseases do not escape the realm of Shanghan.