经曰∶冬三月，此谓闭脏。水冰地坼，无扰乎阳；早卧晚起，必待日光；使志若伏若
匿，若有私意，若已有得；去寒就温，无泄皮肤，使气亟夺，此冬气之应，养脏之道也。
逆之即伤肾，春为痿厥，奉生者少。
又曰∶阳虚生外寒者，阳受气于上焦，以温皮肤分肉之间。今寒气在外，上焦不通。
上焦不通，则寒气独留于外，故寒栗。
阴盛生内寒者，因厥气上逆，寒气积于胸中而不泄。不泄则温气去，寒独留，留则血
凝，血凝则脉不通，其脉盛大以涩，故中寒。
又曰∶寒气入经而稽迟，泣而不行。客于脉外则血少，客于脉中则气不通，故卒然而
痛。因重中于寒，则痛久矣。
寒气客于脉外则脉寒，脉寒则缩蜷，缩蜷则脉绌急，绌急则外引小络，故卒然而痛，得
热则痛立止。
寒气上及小腹，血泣在下相引，故腹痛引阴股。寒气客于小肠膜原之间，络血之中，血
泣不得注于大经，血气积留不得行，故宿昔而成积。
寒气客于五脏，厥逆上出，阴气竭，阳气未入，故卒然痛死不知人；气得复反则生
矣。寒气客于肠胃，厥逆上出，故痛而呕也。寒气客于小肠，小肠不得成聚，故后泄腹痛。
《原病式》曰∶诸病上下，所出水液，澄澈清冷，下利清白，吐利腥秽，食已不饥，
坚痞，腹满急痛， 瘕癫疝，屈伸不便，厥逆禁固，皆属于寒。
《黄帝内经》说：冬季的三个月，叫做“闭藏”。此时水结冰、地开裂，不要扰动阳气；早睡晚起，一定要等到太阳出来；使情志像潜伏隐藏一样，好像有不可告人的秘密，又好像已经得到了满足；远离寒冷，靠近温暖，不要使皮肤开泄出汗，导致阳气频繁耗损，这是顺应冬气、养护肾脏的方法。违背这一规律就会损伤肾脏，到了春天容易发生痿证和厥证，因为供给春季生发之气的物质基础减少了。
又说：阳虚产生外寒，是因为阳气从上焦获得，用来温煦皮肤和肌肉之间。现在寒气在体表，导致上焦不通畅。上焦不通畅，寒气就单独停留在体表，所以出现寒战发抖。
阴盛产生内寒，是因为厥逆之气向上冲逆，寒气积聚在胸中而不能发散。不能发散则温煦之气离去，只有寒气停留，寒气停留则血液凝滞，血液凝滞则脉道不通，脉象表现为盛大而涩，所以感到内部寒冷。
又说：寒气侵入经脉，运行迟缓，血液凝涩而不流动。寒气客居在脉外，则血液减少；客居在脉中，则气机不通，所以突然发生疼痛。如果再次受到寒邪侵袭，疼痛就会持续很久。
寒气客居在脉外，则经脉受寒，经脉受寒则收缩卷曲，收缩卷曲则经脉拘急，经脉拘急则牵引细小的络脉，所以突然发生疼痛，得到温热后疼痛立即停止。
寒气上行至小腹，血液凝涩在下部相互牵引，所以腹痛牵引到腹股沟。寒气客居在小肠的膜原之间和络脉血液中，血液凝涩不能注入大的经脉，气血积聚停留不能运行，所以经过一段时间形成积块。
寒气客居在五脏，导致厥逆之气向上冲出，阴气竭尽，阳气未能入里，所以突然疼痛致死、不省人事；如果气机能恢复返回，就能存活。寒气客居在肠胃，导致厥逆之气向上冲出，所以疼痛并且呕吐。寒气客居在小肠，小肠不能正常聚化食物，所以出现腹泻和腹痛。
《原病式》说：凡是身体上下排出的水液，清澈透明且寒冷，下利颜色清白，呕吐物带有腥臭味，吃完东西却不觉得饿，坚硬痞块，腹部胀满紧急疼痛，瘕疝（腹中结块或睾丸肿痛），屈伸不便，四肢厥冷僵硬，都属于寒证。
The *Classic of Difficult Issues* (Jing Yue Quan Shu cites *Huangdi Neijing*) states: The three months of winter are called "closing and storing" (Bi Zang). At this time, water freezes and the earth cracks; one should not disturb Yang Qi. Sleep early and rise late, waiting until sunlight appears. Let your will be like something hidden or concealed, as if harboring a private secret, or as if already satisfied. Avoid cold and seek warmth; do not allow the skin to sweat, which would cause frequent depletion of Qi. This is responding to the Qi of winter and the way to nourish the Kidney organs. Violating this will damage the Kidneys, leading to Wei Jue syndrome (flaccidity and cold extremities) in spring, because there is less to support the generation of life.
It also states: When Yang deficiency generates external cold, it is because Yang Qi receives its influence from the Upper Jiao (Upper Burner) to warm the skin and intermuscular spaces. Now, when cold pathogen is outside, the Upper Jiao becomes obstructed. If the Upper Jiao is obstructed, cold pathogen remains alone on the exterior, thus causing chills and shivering.
When Yin excess generates internal cold, it is due to Jue Qi (rebellious Qi) moving upward, causing cold pathogen to accumulate in the chest without dispersing. If it does not disperse, warming Qi departs, leaving only cold. Where cold remains, blood coagulates; where blood coagulates, the vessels become obstructed. The pulse becomes large and rough, hence internal cold arises.
It also states: When cold pathogen enters the meridians, its movement slows down, and blood flows sluggishly or stagnates. If it lodges outside the vessels, blood volume decreases; if it lodges inside the vessels, Qi circulation is blocked, resulting in sudden pain. If repeatedly struck by cold, the pain persists for a long time.
When cold pathogen lodges outside the vessels, the vessels become cold; when vessels are cold, they contract and curl; when they contract and curl, they become taut and tight; when taut and tight, they pull on the small collateral vessels, causing sudden pain. Upon receiving heat, the pain stops immediately.
If cold pathogen ascends to the lower abdomen, blood stagnation below draws upon each other, causing abdominal pain that radiates to the inner thighs. If cold pathogen lodges between the mesenteric membranes and within the collateral blood vessels of the Small Intestine, blood stagnates and cannot flow into the major meridians. Blood and Qi accumulate and fail to circulate, thus forming masses over time.
If cold pathogen lodges in the five Zang organs, rebellious Qi rushes upward, Yin Qi is exhausted, and Yang Qi fails to enter, causing sudden severe pain, death-like state, and unconsciousness. If Qi returns, life is preserved. If cold pathogen lodges in the stomach and intestines, rebellious Qi rushes upward, causing pain and vomiting. If cold pathogen lodges in the Small Intestine, the Small Intestine fails to complete its function of gathering and transforming, resulting in diarrhea and abdominal pain.
The *Yuan Bing Shi* (Treatise on the Original Causes of Disease) states: All diseases involving fluids excreted from above and below, whether clear and cold, or presenting as clear-white diarrhea, or foul-smelling vomit and diarrhea, loss of appetite after eating, hard epigastric fullness, acute abdominal distension and pain, Jian Hernia (abdominal masses or hernias), difficulty in flexion and extension, and cold limbs with rigidity, all belong to Cold.