夫痧即是疹，疹即是痧，本属一类，因各处称名
不同耳。如吴地称为痧子，浙人称为瘜子，川陕称为
疹子，山东称为麻子是也。古人论斑为阳明热毒，点
大而色鲜。疹为太阴风热，点细而色红。瘰为脾肺湿
热，连片而红肿。更有丹者，心肺火毒，遍体红晕而
兼斑疹也。瘖者，肺胃湿热，粒如水晶，不甚稠密
也。然考诸方书，斑也、疹也、丹也、瘰也，不外心
脾肺胃之热毒。或斑中兼疹，疹中兼丹，丹中兼瘰，
总无一种独发之理。然疹与瘰发，则搔痒无度，每兼
腹痛。惟瘜系肺胃湿热，只在气分，蒸逼随汗外泄而
成，本属气虚，理宜清气，近时医辈，竟以治痧之法
治瘖，谬之甚焉。殊不知斑、痧、疹、瘰，皆由风热
湿火蕴郁而成，非发不愈，故用疏透。至瘖则湿从热
化，气随汗泄，故宜清气。若见瘖而更以疏泄透汗，
则气液外泄，热势反增。曾见汗泄一次，瘖发一身，
医为未尽，再汗再瘖。一汗一瘖，蔓延无已，竟有不
死不体之弊。吁!医说有理，病听欣然，一旦气脱，
亦不过付之数与命，谁言医之咎耶?总之，斑宜清
化，勿宜提透，痧宜透泄，勿宜温散;瘖宜清气，勿
宜壅遏，丹宜化毒，勿宜温散，瘖宜清气，勿宜疏
散，斯为治法之大要。至于经常权变，神而明之，存
乎其神焉。
痧就是疹，疹就是痧，本质上属于同一类疾病，只是因为各地称呼不同罢了。例如吴地称为“痧子”，浙江人称为“瘜子”（注：原文此处及后文多处用字存在异体或通假争议，结合语境及后文“瘖者...粒如水晶”描述，此处应指白喉或类似咽喉病变，但原文写作“瘜/瘖”，依原文翻译），四川和陕西称为“疹子”，山东称为“麻子”。古人论述斑为阳明经热毒所致，斑点大而颜色鲜艳；疹为太阴经风热所致，斑点细而颜色红；丹为脾肺湿热所致，连成一片且红肿；更有丹毒者，是心肺火毒，遍体红晕并兼有斑疹；瘖（此处指一种皮肤或黏膜病变，特征为颗粒状）则是肺胃湿热所致，颗粒像水晶一样，不太稠密。然而考证各类医书，斑、疹、丹、瘰等病，不外乎心、脾、肺、胃的热毒引起。或者斑中兼有疹，疹中兼有丹，丹中兼有瘰，总之没有单独只发一种病的道理。但是疹与瘰发出时，会瘙痒难耐，常常伴有腹痛。只有瘜（瘖）系肺胃湿热，只在气分，蒸腾逼迫随汗液外泄而成，本属气虚，理应清气。近时的医生，竟然用治痧的方法来治瘖，错误非常严重。殊不知斑、痧、疹、瘰，都是由风热湿火蕴郁而成，不通过发散透邪就不能痊愈，所以使用疏透法。至于瘖，则是湿从热化，气随汗泄，所以适宜清气。如果见到瘖反而用疏泄透汗的方法，那么气液就会外泄，热势反而增加。曾见过因为发汗一次，瘖发满一身，医生认为治疗不彻底，再次发汗再次出瘖。一汗一出瘖，蔓延不止，竟有导致身体衰败死亡的弊端。唉！医生说有理，病人听得很高兴，一旦气脱，也不过归结于命运和天命，谁会说是医生的过错呢？总之，斑宜清化，不宜提透；痧宜透泄，不宜温散；瘖宜清气，不宜壅遏；丹宜化毒，不宜温散；瘖宜清气，不宜疏散，这是治疗的大要。至于常规的权变，神妙明达，存乎于心神之中。
Sha (sand rash) is essentially Zhen (rash), and Zhen is Sha; they belong to the same category, differing only in regional names. For instance, in the Wu region it is called "Sha Zi," in Zhejiang "Xi Zi" (or "Yin"), in Sichuan and Shaanxi "Zhen Zi," and in Shandong "Ma Zi." Ancient texts describe Ban (macules) as caused by Yangming heat-toxin, with large spots and bright color; Zhen (papules/rash) as caused by Taiyin wind-heat, with fine spots and red color; Dan (erysipelas/redness) as caused by Spleen-Lung damp-heat, appearing as connected patches of redness and swelling; and more severe Dan cases involve Heart-Lung fire-toxin, with whole-body redness accompanied by macules and rashes. Yin (a specific lesion described here as crystal-like granules, not dense) is caused by Lung-Stomach damp-heat, manifesting as granules like crystal, not very dense. However, consulting various medical books, Ban, Zhen, Dan, and Lei are all attributable to heat-toxins in the Heart, Spleen, Lung, and Stomach. One may find Ban combined with Zhen, Zhen with Dan, or Dan with Lei; there is no case where only one type erupts alone. Nevertheless, when Zhen and Lei erupt, they cause extreme itching and often accompany abdominal pain. Only Xi/Yin stems from Lung-Stomach damp-heat remaining in the Qi level, steaming and forcing out through sweat; it fundamentally involves Qi deficiency and should be treated by clearing Qi. Recent physicians erroneously apply methods for treating Sha to treat Yin, a grave mistake. It is unknown that Ban, Sha, Zhen, and Lei are all formed by the accumulation and stagnation of wind-heat, dampness, and fire, requiring eruption and venting to heal, thus necessitating dispersing and penetrating methods. In contrast, for Yin, dampness transforms into heat, and Qi escapes with sweat, so clearing Qi is appropriate. If one uses dispersing and sweating methods for Yin, Qi and fluids will leak outward, and the heat condition will worsen. I have seen cases where after one episode of sweating, Yin erupted over the whole body; believing the treatment incomplete, the physician induced sweating again, leading to more Yin. Each sweating episode triggered more Yin, spreading endlessly, potentially causing fatal exhaustion. Alas! The physician claims rationality, the patient listens willingly, but once Qi collapses, it is merely attributed to fate, and who blames the physician? In summary: Ban should be cleared and transformed, not lifted and penetrated; Sha should be vented and drained, not warmed and dispersed; Yin should clear Qi, not be obstructed; Dan should resolve toxins, not be warmed and dispersed; Yin should clear Qi, not be scattered. These are the major principles of treatment. As for adapting to constant changes, divine understanding lies within the mind.