凡治病，必先辨明寒、热、虚、实。望闻问切，无非辨此四者而已。四者了然胸中，则
用药取效，其应如响。四者不能分辨，鲜有不误者。即或中病而愈，亦幸而偶中也。至于痘
症之寒、热、虚、实，尤为紧要，辨之不明，多致败事。何历代治痘之家，着书立方，互相
异同，至于虚、实、寒、热，多略而不辨，或辨而不明。致令检方者，漫无下手处，竟不知
某症属虚热，某症属实热，当用某方，则虽千百妙方，千百妙论，无益于用也。无怪乎自古
及今，治痘之家多迷途，而慈幼之术疏也。且痘之虚、实、寒、热，与诸症之虚、实、寒、
热，固自有辨。诸症有虚者，元气虚也，宜补之。痘有表虚，有里虚，亦元气虚也，宜补之
。此其相同者也。诸症有实者，邪气实也，宜泻之。痘有表实，有里实，此则元气完固，毒
气不能为害，不可泻，亦不必泻也。此其不同者也。诸症有虚之甚者，阴有余而阳不足，则
寒自虚生，宜温热之剂补之也。痘有虚之甚者，亦阴有余而阳不足，而寒自虚生，亦宜温热
之剂补之也。此其相同者也。诸症有寒自外入者，外感也，当其在表，宜发散之。久而入里
，则郁而为热，宜清解之。痘出而风寒外袭，宜温而散之，或外寒入内而为吐泻诸症，则宜
温之而已，外不可发汗，内不可清解也。诸症有虚热者，元气虚，精液竭，而火从虚生，补
之则热自除，不必解热也。痘亦有虚热者，元气虚而毒瓦斯肆也，当以补元气为主，而略兼解
毒可也。三者皆同有不同也。诸症有实热者，血气未亏而邪气壅盛，单用寒凉之药泻之可也
。痘亦有实热者，禀气强、血气盛而毒瓦斯亦盛，亦单用清凉解之可也。此又其相同者也。今
自发热之初，以至还元之后，俱先辨痘之虚、实、寒、热，而各立方于后，令人细心审症而
后用药，庶不致虚虚而实实乎，不致于损不足而补有余乎，不致于以水益寒而以火益热乎。
然痘之虚、实、寒、热，较之他症尤显而易察。盖自见点以致结痂，其形其色，既昭昭然而
可睹，又听其声音，观其静躁，视其饮食之多少，大小便之利涩，三岁以上切其脉之迟、数
、洪、细，辨虚、实、寒、热，当于黑白之分明而后用药，取效易易矣。！
凡是治疗疾病，必须先辨明寒、热、虚、实。望、闻、问、切四种诊法，无非是为了辨别这四个方面罢了。如果将这四个方面在胸中了然于指掌，那么用药取效，反应就会像回声一样迅速。如果不能分辨这四个方面，很少有不失误的。即使偶尔治好了病，也只是侥幸碰巧罢了。至于痘症（天花）的寒、热、虚、实，尤为紧要，辨别不清楚，往往导致事情失败。为什么历代治疗痘症的医家，著书立说、制定方剂，互相之间观点各异，对于虚、实、寒、热，大多忽略而不加辨析，或者辨析得不够明确。致使查阅方书的医者，无从下手，竟然不知道某种症状属于虚热，某种症状属于实热，应当使用哪种方剂，那么即使有千百个妙方、千百条妙论，对实际应用也没有益处。难怪从古至今，治疗痘症的医家多迷失方向，而爱护幼儿的技术也就疏略了。况且痘症的虚、实、寒、热，与其他病症的虚、实、寒、热，本来就有区别。其他病症有虚证，是元气虚弱，适宜用补法。痘症有表虚、有里虚，也是元气虚弱，适宜用补法。这是相同的地方。其他病症有实证，是邪气盛实，适宜用泻法。痘症有表实、有里实，这是因为元气完固，毒气不能为害，不可用泻法，也不必用泻法。这是不同的地方。其他病症有极度的虚证，阴气有余而阳气不足，则寒气从虚而生，适宜用温热的药剂来补益。痘症有极度的虚证，也是阴气有余而阳气不足，寒气从虚而生，也适宜用温热的药剂来补益。这是相同的地方。其他病症有寒气从外侵入的，属于外感，当病邪在体表时，适宜用发散的方法。时间久了传入体内，则郁结化为热，适宜用清热解表的方法。痘症发出后若受风寒外袭，适宜用温和的方法发散；或者外寒入内导致呕吐腹泻等症状，则适宜温中而已，体表不可发汗，体内不可清热解表。其他病症有虚热，是元气虚弱，精液枯竭，火气从虚而生，补益正气则热自除，不必专门清热。痘症也有虚热，是元气虚弱而毒瓦斯肆虐，应当以补益元气为主，略微兼用解毒即可。这三者都有同有不同。其他病症有实热，是血气未亏损而邪气壅盛，单用寒凉的药物泻火即可。痘症也有实热，是禀赋之气强盛、血气旺盛而毒瓦斯也盛，也单用清凉的方法解除即可。这又是相同的地方。现在从发热之初，直到还元之后，都先辨别痘症的虚、实、寒、热，然后在后面分别列出方剂，让人细心审察症状后再用药，这样才不至于使虚者更虚、实者更实，不致于损害不足而补益有余，不致于用水增加寒冷而以火增加炎热。然而痘症的虚、实、寒、热，比其他病症更容易观察清楚。因为从出疹点到结痂，其形态和颜色，既然明显可见，又听其声音，观察其安静或躁动，查看其饮食的多少，大小便的通利或涩滞，三岁以上的患儿切按其脉搏的迟、数、洪、细，辨别虚、实、寒、热，应当在黑白分明之后才用药，取得疗效就容易了。
In treating any disease, one must first clearly distinguish between Cold (Han), Heat (Re), Deficiency (Xu), and Excess (Shi). The four diagnostic methods of Observation (Wang), Listening and Smelling (Wen), Inquiry (Wen), and Palpation (Qie) are all aimed at distinguishing these four aspects. If these four aspects are clearly understood in the mind, then the efficacy of medication will be as immediate as an echo. If these four cannot be distinguished, errors are rarely avoided. Even if the disease is cured by chance, it is merely a lucky coincidence. Regarding the Cold, Heat, Deficiency, and Excess of Smallpox (Dou Zheng), this distinction is particularly crucial; failure to clarify them often leads to treatment failure. Why is it that physicians throughout history who have written books and formulated prescriptions for Smallpox have held differing views? They often neglected or failed to clearly distinguish between Deficiency, Excess, Cold, and Heat. This leaves practitioners consulting these texts without a clear starting point, unable to determine which symptoms belong to Deficient Heat (Xu Re) and which to Excess Heat (Shi Re), nor which formula to use. Consequently, even with thousands of excellent formulas and theories, they are of no practical use. No wonder that from ancient times to the present, many Smallpox physicians have lost their way, and the art of caring for infants has become neglected.
Furthermore, the Deficiency, Excess, Cold, and Heat of Smallpox differ inherently from those of other diseases. In other diseases, Deficiency refers to the deficiency of Yuan Qi (Primal Qi), which requires tonification. In Smallpox, there is Exterior Deficiency (Biao Xu) and Interior Deficiency (Li Xu), also stemming from Yuan Qi deficiency, which likewise requires tonification. This is a similarity. In other diseases, Excess refers to the excess of pathogenic factors, requiring purgation. In Smallpox, Exterior Excess and Interior Excess indicate that the Yuan Qi is solid and the toxin cannot cause harm; thus, purgation is neither indicated nor necessary. This is a difference. In other diseases, severe Deficiency implies an excess of Yin and insufficiency of Yang, leading to Cold generated from Deficiency, which should be treated with warm and hot tonifying agents. In Smallpox, severe Deficiency similarly involves an excess of Yin and insufficiency of Yang, generating Cold from Deficiency, and also requires warm and hot tonifying agents. This is a similarity. In other diseases, Cold entering from the exterior is an external contraction; when the pathogen is on the surface, dispersing methods are appropriate. If it lingers and enters the interior, it stagnates and transforms into Heat, requiring clearing and resolving methods. In Smallpox, if Wind-Cold attacks after eruption, mild dispersing methods are appropriate. If external cold enters the interior causing vomiting and diarrhea, warming methods are sufficient; exterior diaphoresis is contraindicated, and interior clearing/resolving is not indicated. In other diseases, Deficient Heat arises from deficient Yuan Qi and exhausted essence/fluids, with Fire generated from Deficiency; tonification removes the heat without needing specific heat-clearing. In Smallpox, Deficient Heat involves deficient Yuan Qi and rampant toxins; the primary approach is to tonify Yuan Qi, with slight adjunctive detoxification. These three categories share both similarities and differences. In other diseases, Excess Heat occurs when blood and qi are not yet depleted but pathogens are abundant; simple cooling and purging herbs suffice. In Smallpox, Excess Heat occurs when constitution is strong, blood and qi are robust, and toxins are also abundant; simple cooling and resolving methods suffice. This is another similarity.
From the initial fever until recovery, one must first distinguish the Deficiency, Excess, Cold, and Heat of Smallpox, and subsequently prescribe formulas accordingly. This allows practitioners to carefully assess symptoms before medicating, thereby avoiding making Deficiency more Deficient and Excess more Excessive, preventing damage to what is insufficient while augmenting what is already excessive, and avoiding adding water to coldness or fire to heat. However, the Deficiency, Excess, Cold, and Heat of Smallpox are more readily observable than those of other diseases. From the appearance of spots to scabbing, the morphology and color are clearly visible. By listening to the voice, observing calmness or agitation, checking food and fluid intake, and assessing the ease or difficulty of urination and defecation, and by palpating the pulse (Slow Chi, Rapid Shuo, Surging Hong, Fine Xi) in children over three years old, one can distinguish Deficiency, Excess, Cold, and Heat. Once these distinctions are as clear as black and white, prescribing medication becomes straightforward and effective results are easily achieved.