夫四肢属脾为诸阳之本，初发热手暖足凉者，此正候也。盖肾生足，肾不受邪，故
能足凉，脾主手，脾旺循经，故克手暖。如初发热而手寻衣领，及乱捻物者，肝热也。
手搜眉目口鼻者，肺热也。手足搐搦者，心肝风火相传，手中足冷者，脾胃怯也。盖四
肢皆禀气于胃，与脏胸道路稍远耳。若脾怯不能为胃行其津液，乃不得至经，故即冷
耳。如疮已出现而手足多水泡者，此肝胜脾衰，鬼蜮来克，最宜急治，泻肝补脾，以防
疮塌而死，然报点时，须两手臂较诸头而透出稍迟者，吉。恐先发松，则元首透出益迟
矣。如应至不至者，此又脾胃气虚，不能旁达四肢也。并遍身皆发而手足不透，或空壳
者，皆是脾胃虚弱，津液耗竭，荣卫凝涩，不得流通灌溉四肢，故其毒亦郁而不发。如
不能食者，死。能食者，必发痈疽。更有方始行浆，而他处未收，惟手足心先靥者，其
后必生怪疾。若痘靥之后，而手足关节肿痛者，必毒未解散，须防发痈，至如痘未成浆
而手足皮脱者，死。并疮势太甚，手足冷者，不治。及疮痒而手足搔乱者，凶，并见
而复隐起而复塌，其色紫黑者为肾乘脾也，不治。
夫痘疮变黑，有犹可治者；有不可治者，何欤？盖此一症，关系逆侯治之贵早，
缓则蔓延传变，倏出倏没，迤逦而死，凡四围有水，中心黑陷者，只用胭脂涂法，直待
转红起胖而止，若起发有水，顶平而黑者，宜内服凉血解毒，剂中加烧人粪。外亦胭脂
涂法，若大便不通者，此里热熏蒸得之，宜内服清凉解毒疏利之剂，外用胆导之法。如
泄泻者，此处寒也，宜用大温补气之剂。痘若干黑脚根坚硬者，可用银针刺去毒血，以
油胭脂调四圣散纳之，若再皮肉不HT ，根脾不肿，烦躁闷乱不食者，决无生理也。
四肢归属于脾，是诸阳经的根本。起初发热时，手暖脚凉，这是正常的征象。因为肾主管足部，肾未受邪气侵袭，所以脚凉；脾主管手部，脾气旺盛沿经脉运行，所以手暖。如果初起发热时，手去抓衣领，或者胡乱捻弄物品，这是肝热的表现。手去摸眉毛、眼睛、口鼻的，是肺热的表现。手足抽搐拘挛的，是心火与肝风相互传变所致；手中指和足趾冷的，是脾胃虚弱怯懦的表现。因为四肢都禀受胃气，但距离脏腑所在的胸腹部位稍远罢了。如果脾气虚弱，不能为胃传输津液，津液就无法到达经脉，所以手脚就会发冷。如果痘疮已经发出，而手脚上有很多水泡的，这是肝气胜而脾气衰，邪气克制正气，最应当紧急治疗，采用泻肝补脾的方法，以防止痘疮塌陷而死。然而，在报点（痘疹初现）时，必须两手臂比头部透出稍晚一些的，才是吉兆。恐怕先发出来的松散，那么头部的痘疹透出就更迟了。如果到了该发出的时候却没有发出，这是脾胃气虚，不能将气血旁达四肢。并且遍身都发了，唯独手脚没有透出，或者是空壳状的，都是脾胃虚弱，津液耗竭，营卫之气凝滞涩涩，不能流通灌溉四肢，所以毒邪也郁结而不能发出。如果不能进食的，会死。能进食的，必定会并发痈疽。更有刚开始行浆（痘疹化脓），而其他部位还没有收靥（结痂），唯独手心脚心先结痂的，其后必定生出怪异的疾病。如果痘疮结痂之后，而手脚关节出现肿痛，一定是毒邪没有解散，必须防止发生痈肿。至于痘疮还未成浆而手脚皮肤脱落的，会死。并且疮势太盛，手脚冰冷的，无法医治。以及痘疮瘙痒而手脚乱抓挠的，凶险，并且痘疹见而复隐、起而复塌，颜色紫黑的，是肾气乘袭脾土，无法医治。
痘疮变成黑色，有还可以治疗的；有不可治疗的，为什么呢？因为这个症状，关系到逆证的判断，治疗贵在早，迟缓则会蔓延传变，忽出忽没，逐渐死去。凡是四周有水泡，中心黑陷的，只用胭脂涂抹的方法，一直等到转红、隆起饱满才停止。如果起发时有水泡，顶部平坦而黑色的，适宜内服凉血解毒的药物，药方中加入烧过的人粪。外用也是胭脂涂抹法。如果大便不通的，这是里热熏蒸所致，适宜内服清凉解毒、疏通利下的药物，外用胆导法（用猪胆汁灌肠）。如果出现泄泻的，这是寒证，适宜使用大温补气之剂。痘疮如果根部坚硬且干枯发黑的，可以用银针刺破排出毒血，然后用油调制的四圣散纳入其中。如果再皮肉不愈合，根盘不肿胀，烦躁闷乱、不能进食的，绝对没有生机了。
The four limbs belong to the Spleen and serve as the root of all Yang channels. Initially, when fever begins, if the hands are warm and the feet are cool, this is a normal sign. This is because the Kidney governs the feet; since the Kidney has not been invaded by pathogenic factors, the feet remain cool. The Spleen governs the hands; as Spleen Qi is vigorous and flows along its meridians, the hands become warm. If during the initial fever, the patient reaches for clothing collars or randomly fiddles with objects, this indicates Liver Heat. If the hands touch the eyebrows, eyes, mouth, or nose, this indicates Lung Heat. Twitching and spasms of the four limbs indicate that Heart Fire and Liver Wind are transmitting to each other; coldness in the hands and feet indicates Spleen and Stomach deficiency and timidity. This is because the four limbs receive their Qi from the Stomach, but they are slightly distant from the chest and abdomen where the Zang organs reside. If Spleen deficiency fails to transport fluids for the Stomach, these fluids cannot reach the meridians, resulting in coldness. If vesicles appear on the hands and feet after the eruption of smallpox lesions, this signifies Liver excess and Spleen decline, with pathogenic factors overcoming healthy Qi. Urgent treatment is required, employing methods to drain the Liver and tonify the Spleen, to prevent lesion collapse and death. However, at the stage of initial spotting (Bao Dian), it is auspicious if the eruptions on both arms appear slightly later than those on the head. One must fear that if early eruptions are loose, the head's eruptions will emerge even more slowly. If eruptions fail to appear when they should, this is due to Spleen and Stomach Qi deficiency, preventing the distribution of Qi and Blood to the limbs. Furthermore, if eruptions cover the whole body but do not appear on the hands and feet, or if they are empty shells, these are all signs of Spleen and Stomach weakness, exhaustion of body fluids, and stagnation of Ying and Wei Qi, which cannot circulate and nourish the limbs. Consequently, the toxin remains郁结 (stagnant) and cannot erupt. Inability to eat indicates death. Ability to eat suggests a likely complication of carbuncles and sores. Additionally, if pustulation has begun elsewhere but scabbing has not occurred, yet the palms and soles scab first, strange diseases will likely follow. If joint swelling and pain occur in the hands and feet after the scabbing phase, it indicates unresolved toxins, requiring vigilance for abscess formation. If skin desquamation occurs on the hands and feet before the lesions form pus, it indicates death. Severe eruption accompanied by cold hands and feet is incurable. Itching with restless scratching of the hands and feet is ominous. Lesions that appear and disappear repeatedly, collapse again, and turn purple-black indicate Kidney overacting on the Spleen, which is incurable.
Smallpox lesions turning black may be treatable or untreatable. Why? This condition relates to adverse prognostic signs; early treatment is crucial. Delay leads to spread and transformation, with lesions appearing and disappearing suddenly, leading to gradual death. For lesions surrounded by fluid with a central black depression, only apply Rouge (Yanzhi) externally until the color turns red and the lesion rises and plumps up. For lesions that have risen with fluid, have a flat top, and are black, internal administration of blood-cooling and detoxifying formulas is appropriate, adding calcined human feces to the prescription. Externally, apply Rouge. For constipation, caused by internal heat steaming, administer internal cooling, detoxifying, and purgative formulas, and use external bile enema (Dan Dao). For diarrhea, indicating cold, administer strongly warming and Qi-tonifying formulas. If the base of the blackened lesion is hard, prick out toxic blood using a silver needle, then apply Si Sheng San (Four Sages Powder) mixed with oil into the wound. If the skin and flesh do not heal, the base does not swell, and the patient suffers from restlessness, oppression, confusion, and anorexia, there is absolutely no hope for survival.