夫痘欲其疏，疏则毒少，不欲其密，密则毒盛，然疏密之分，尤有喜忌焉，如头面
欲疏，是元首不可犯也。颈项欲疏，是管龠不可塞也。胸膛欲疏，是神明之地，心肺之
居，不可触也。腹背欲疏，是脏腑俞募之所附也。若夫手足则不忌其密矣。谓之疏者，
非但稀少也，即铺拂磊落，大小匀净，亦可以言疏，故不论疏密，而贵论磊落，颗粒分
明，尖圆紧实，虽密无妨，谓之密者，非必盛多也。即攒聚粘连，片复一片，模糊作
块，不分珠点，虽只数处，亦可以言密，兼初出时红点才见数处，其表里热候便退者，
此即可语其疏也。苟见点虽少，而大热不解，唇口燥裂，大小便秘，烦燥不宁，诸候
未减，由此毒盛郁遏于中，不能逐出，故必日复更密，是即初出虽少，未可遽言其疏
也。
夫物湿则润泽，燥则干枯。然痘荣枯之分，血实主之。血者，所以营阴阳，濡皮
毛，流关节也；若疮本疏者，则血不在多，而自易充足。惟疮本稠密者，则贵乎血之有
余，则经脉流行，沦于肌肤，泱于皮毛，灌溉滋润，肥泽长养，自然形色鲜明，根窠红
活也。如血不足，则经脉壅遏，囊窠空虚，乃黑燥而不鲜明，枯萎而不润泽，皮肝皱揭
而启裂矣。故《经》曰∶诸涩枯涸，干劲皱揭，皆属于燥。盖由其人血常不足，如以毒
火熏灼反兼燥令之化，是以精血为之更竭也。治宜活血凉荣，散热解毒，滋金润燥，
则干涸渐可挽回矣。
痘疹（天花）的形态以稀疏为吉，稀疏则毒邪较轻；以稠密为忌，稠密则毒邪炽盛。然而，对于疏与密的区分，还有其特定的喜恶标准。例如，头面部希望稀疏，因为头部是元首所在，不可受犯。颈项部希望稀疏，因为这里是气机升降的通道（管龠），不可阻塞。胸膛希望稀疏，因为这是心神所居之地，也是心肺所在的部位，不可受到侵犯。腹部和背部希望稀疏，因为这里是脏腑俞穴和募穴依附的地方。至于手足部位，则不忌讳其稠密。
所谓“疏”，不仅仅是指数量稀少，即使是分布均匀、磊落分明、大小洁净整齐，也可以称为疏。因此，不论疏密，关键在于是否磊落分明，颗粒清晰，形状尖圆且紧实，即使稠密也无妨。所谓“密”，并不一定是指数量众多，即使是聚集粘连，层层覆盖，模糊成块，分不清颗粒，即使只有几处，也可以称为密。另外，在痘疹刚发出时，如果表面仅见几点红点，但体内的热象随即消退，这就可以说是疏。如果见到痘点虽然少，但大热不退，嘴唇口腔干燥开裂，大小便不通畅，烦躁不安，各种症状没有减轻，这是因为毒邪炽盛郁结在体内，无法排出，所以必然日复一日变得更加稠密。这就是说，初起时虽然痘点少，但不能立即断定其为疏。
事物湿润则润泽，干燥则干枯。然而，痘疹的荣润与枯槁之分，主要由血液的状态决定。血的作用是营养阴阳，濡养皮毛，流通关节。如果疮疹原本就稀疏，那么血液不需要很多，自然容易充足。只有当疮疹原本就稠密时，才贵在血液有余，这样经脉才能流行，渗透于肌肤，充盈于皮毛，灌溉滋润，肥泽生长，自然形色鲜明，根脚红活。如果血液不足，则经脉壅塞阻滞，痘囊空虚，就会变得黑燥而不鲜明，枯萎而不润泽，皮肤皱缩揭裂。所以《内经》说：凡是涩滞、干枯、劲急、皱揭的症状，都归属于燥证。这是由于人体血液常不足，如被毒火熏灼，反而兼有燥令的变化，使得精血更加枯竭。治疗应当采用活血凉营、散热解毒、滋肺润燥的方法，那么干涸的情况逐渐可以挽回。
The eruption of smallpox (Dòuzhěn) is auspicious when sparse, as sparsity indicates less pathogenic toxin; it is inauspicious when dense, as density indicates excessive pathogenic toxin. However, the distinction between sparsity and density has specific preferences and taboos. For instance, the head and face should be sparse, because the head is the "chief" and must not be invaded. The neck should be sparse, because this area is the passage for Qi mechanism (Guǎnyuè) and must not be blocked. The chest should be sparse, because this is the residence of the Mind (Shénmíng) and the location of the Heart and Lungs, which must not be touched. The abdomen and back should be sparse, because these are the areas where the Back-Shu and Front-Mu points of the Zang-Fu organs are attached. As for the hands and feet, density is not taboo.
What is called "sparse" does not merely mean few in number; even if distributed evenly, distinct, and clean with uniform size, it can still be termed sparse. Therefore, regardless of density, what is valued is being distinct and clear, with granules that are sharp, round, tight, and solid; even if dense, it is no hindrance. What is called "dense" does not necessarily mean numerous; even if clustered and adhering, layer upon layer, blurred into masses without distinct granules, even if only in a few places, it can be termed dense. Furthermore, at the initial stage of eruption, if only a few red spots appear on the surface but the internal heat symptoms subside immediately, this can be considered sparse. If, however, although the spots are few, the high fever persists, lips and mouth are dry and cracked, urination and defecation are obstructed, and there is restlessness and irritability with no reduction in other symptoms, this is because the pathogenic toxin is excessive and stagnated internally, unable to be expelled. Consequently, it will inevitably become denser day by day. Thus, although few in number initially, one cannot hastily conclude it is sparse.
Things that are moist are nourished and lustrous, while those that are dry are withered and arid. However, the distinction between flourishing (Róng) and withering (Kū) of the eruption is primarily governed by Blood. Blood serves to nourish Yin and Yang, moisten skin and hair, and flow through joints. If the eruption is originally sparse, Blood need not be abundant to naturally suffice. Only when the eruption is originally dense is it crucial that Blood is sufficient, allowing the meridians to circulate freely, permeating the muscle tissue, filling the skin and hair, irrigating and moistening, promoting growth and nourishment, resulting naturally in bright color and vitality, with red and active bases. If Blood is insufficient, the meridians become congested and stagnant, the pustule bases become empty, leading to blackness, dryness, lack of brightness, withering, lack of moisture, and wrinkling or cracking of the skin. Thus, the *Classic* states: All cases of astringency, withering, dryness, stiffness, and wrinkling belong to Dryness. This is due to the person's chronic Blood deficiency; when scorched by toxic fire, it may additionally undergo transformations of Dryness, causing Essence and Blood to become further depleted. Treatment should employ methods to invigorate Blood and cool Ying (Nutrient), dissipate heat and detoxify, nourish Metal (Lung) and moisten Dryness, so that the desiccation can gradually be reversed.