伤寒厥者。何以明之。厥者冷也。甚于四逆也。经曰。厥者阴阳气不相顺接。便为厥。
厥者手足逆冷是也。谓阳气内陷。热气逆伏。而手足为之冷也。经曰。伤寒一二日
至四五日。厥者必发热。前热者后必厥。厥深者热亦深。厥微者热亦微。是知内陷
者。手足为厥矣。少阴病但厥无汗。而强发之。必动其血。未知从何道出。或从口鼻。
或从目出。是名下厥上竭。亦是言发动其热也。先热而后厥者。热伏于内也。先厥
而后热者。阴退而阳气得复也。若始得之便厥者。则是阳气不足。而阴气胜也。大
抵厥逆为阴所主。寒者多矣。而又有进退之别。经曰。病厥五日。热亦五日。设六日
当复厥。不厥者自愈。发热四日。厥反三日。复厥四日。厥少热多。其病自愈。厥四日。
热反三日。复厥五日。其病为进。寒多热少。阳气退。故为进也。病至厥阴。传经尽也。
当是之时。阳气胜阴。厥少热多。其病则愈。若或阴气反胜。阳不得复。厥多热少。其
病则逆。厥为阴气至也。热为阳气复也。至于下利。则曰先厥后发热而利。必自止。
见厥复利。厥者复为热。为阳气得复。而利必自止。热者便为厥。是阴气还胜也。故复下利矣。诸阳受气于胸中邪气客
于胸中郁郁留结。则阳气不得敷布。而手足为之厥。经曰。手足厥冷。脉乍紧。邪结在胸中。心中满而烦。饥不能食。
病在胸中。当吐之者是矣。厥为阴之盛也。若更加之恶寒而蜷者。阴气之极也。则难可制。经曰。少阴病恶寒身蜷而利。
手足厥冷者。不治。是厥冷之逆者。神丹其能生乎。
伤寒病中的厥证，如何阐明其机理呢？所谓“厥”，是指寒冷，比四肢逆冷（四逆）更为严重。经典记载说：“厥”是由于阴阳之气不能顺接贯通，从而形成厥证。所谓的厥，表现为手足逆向寒冷。这是因为阳气内陷，热气郁伏在内，导致手足发冷。经典又说：伤寒发病一二天到四五天，出现厥冷的必然伴有发热，先前发热的随后必定出现厥冷，厥冷越深重，体内的热邪也越深重；厥冷轻微，体内的热邪也轻微。由此可知，阳气内陷会导致手足厥冷。少阴病仅见厥冷而无汗，如果强行发汗，必定扰动血液，不知血液会从哪个通道溢出，有的从口鼻出，有的从眼睛出，这被称为“下厥上竭”，这也是指发动了体内的热邪。先发热而后出现厥冷的，是热邪伏于体内；先厥冷而后发热的，是阴邪退去而阳气得以恢复。如果一开始就出现厥冷的，则是阳气不足而阴气偏盛。大抵厥逆是由阴气所主，多为寒证，但又有病情进退的区别。经典说：患病厥冷五天，发热也五天，假如第六天应当再次出现厥冷，如果没有再厥冷，则疾病自愈。发热四天，厥冷反而三天，接着又厥冷四天，这是厥冷时间短而发热时间长，疾病将自愈。厥冷四天，发热反而三天，接着又厥冷五天，这是病情进展，因为寒多热少，阳气衰退，所以病情加重。病至厥阴经，表示传经已尽。在这个时候，如果阳气胜阴，厥冷少而发热多，疾病就会痊愈。如果阴气反而胜，阳气不能恢复，厥冷多而发热少，疾病就会恶化。厥冷代表阴气到来，发热代表阳气恢复。至于下利（腹泻），如果说先厥冷后发热且腹泻，腹泻必定自行停止；见到厥冷再次出现，腹泻也会再次发生。厥冷转为发热，说明阳气得到恢复，腹泻必定自行停止；若发热转为厥冷，说明阴气重新占优势，因此又会发生下利。诸阳经之气汇聚于胸中，如果有邪气客居在胸中，郁结不散，就会导致阳气无法敷布全身，从而引起手足厥冷。经典说：“手足厥冷，脉象突然紧束，邪气结聚在胸中，心中胀满且烦闷，虽觉饥饿却无法进食。”这是病位在胸中，应当采用涌吐法治疗的情况。厥冷是阴气极盛的表现，如果再加上恶寒且身体蜷缩，则是阴气达到极点，这就难以控制了。经典说：“少阴病，恶寒、身体蜷缩且伴有下利，手足厥冷的，属于不治之症。”像这样严重的厥冷逆证，神丹（指代灵验的药物或疗法）又能使其复活吗？
In the context of Cold Damage (Shanghan), what is meant by "Jue" (Reversal)? Jue refers to coldness, which is more severe than Si Ni (reversal coldness of the four limbs). The Classics state: "When Yin and Yang Qi fail to connect smoothly, it results in Jue." Jue manifests as reversal coldness of the hands and feet. This occurs because Yang Qi sinks inward, and heat qi becomes stagnant and伏 (hidden/repressed) internally, causing the hands and feet to become cold. The Classics further state: "From one or two days to four or five days after contracting Cold Damage, if Jue appears, there must be fever. If there was fever previously, Jue will follow subsequently. The deeper the Jue, the deeper the heat; the milder the Jue, the milder the heat." From this, we know that the sinking of Yang Qi leads to Jue of the hands and feet. In Sha Yin disease, if there is only Jue without sweat, and forced sweating is applied, it will inevitably disturb the blood. It is unknown from which pathway the blood will emerge; it may come out from the mouth or nose, or from the eyes. This is termed "Lower Jue and Upper Exhaustion," which also refers to stirring up the internal heat. If fever precedes Jue, it indicates heat repressed within. If Jue precedes fever, it indicates that Yin pathogenic factors are retreating and Yang Qi is recovering. If Jue appears immediately upon onset, it signifies insufficient Yang Qi and prevailing Yin Qi. Generally, Jue Ni (reversal coldness) is governed by Yin and is mostly cold in nature, yet there are distinctions regarding progression and regression. The Classics state: "If a patient has Jue for five days and fever for five days, and on the sixth day should revert to Jue but does not, the disease will heal spontaneously. If there is fever for four days, Jue for three days, and then Jue again for four days, this means Jue is less and fever is more, indicating the disease will heal spontaneously. If Jue lasts for four days, fever for three days, and then Jue again for five days, the disease progresses. Because cold is more and heat is less, Yang Qi retreats, hence the disease advances." When the disease reaches the Jue Yin stage, the transmission through the meridians is complete. At this time, if Yang Qi overcomes Yin, with less Jue and more fever, the disease will heal. If Yin Qi instead prevails and Yang Qi cannot recover, with more Jue and less fever, the disease will worsen. Jue represents the arrival of Yin Qi, while fever represents the recovery of Yang Qi. Regarding diarrhea (Li), if it is stated that there is initial Jue followed by fever and diarrhea, the diarrhea will stop spontaneously; if Jue reappears, the diarrhea returns. When Jue turns to heat, it means Yang Qi has recovered, and the diarrhea will stop spontaneously. When heat turns to Jue, it means Yin Qi has regained dominance, hence diarrhea recurs. The Qi of all Yang meridians gathers in the chest. If external pathogens lodge in the chest and remain stagnant and knotted, Yang Qi cannot spread and distribute, leading to Jue of the hands and feet. The Classics state: "Coldness of the hands and feet, sudden tightness of the pulse, pathogenic knotting in the chest, fullness and vexation in the heart, feeling hungry but unable to eat—this indicates the disease is located in the chest, and emesis (vomiting) therapy should be employed." Jue represents the flourishing of Yin. If accompanied by aversion to cold and curling up of the body, it indicates the extreme of Yin Qi, which is difficult to control. The Classics state: "In Sha Yin disease, with aversion to cold, curling up of the body, diarrhea, and coldness of the hands and feet, the condition is untreatable." For such severe reversal coldness, how could Shen Dan (miraculous medicine) possibly restore life?