夫水无土则溃，土实则顺，理势然也。盖土为万物之母，而痘疮之起灌成实，皆赖
脾胃化源生发也。倘天元薄劣，脾土损伤，则传送之官失职，生化之机以漓，气血弗克
充灌，于是土溃水浮而泡随发也。然一发泡，则痘囊空虚而不饱满矣。有以气过则为
泡者，当言邪气之过于冲击而为泡也，岂正气充实，不能逐毒化浆而为水泡臭痒之患
哉！有以部位所属五行以断者，虽似乎理，未免多歧，不切治法。总之，头为元首之
尊，胸为受气之地，颈为出入之所，背为五俞之属，正痘尚嫌具多，况水泡乎？惟于手
足，则如卒伍卑贱之属，少见之而不为害，然亦脾虚之足征矣。若至被单交片则为恶
候，乃臭痒之渐也。向有凡疮或破伤未痊，或初痊斑嫩，痘出簇而化为泡者，由外因
而致，非内病而无害也。按古论泡之恶，与黑陷相类，外出内入，势虽不同，而毒滞为
害则一，盖毒瓦斯猛烈，反成郁遏，极则冲突平陷之处，郁遏之处也。水泡之所，冲突之
所也。热毒内伏，驱逐津液先行耳，内宜逐毒松血，外以银针刺破，出其紫血，以芫荽
酒调宫粉涂之。
夫痘色干红，红后必变紫，紫必变黑，黑必变枯陷，此血热毒滞而行，乃内热渐
变，一定之机也。治者，于干红之时，急宜解散凉血，退热清利，此顶虽平陷，不可以
气虚而用参 补剂，否则，气盛而血愈干涸矣。丹溪曰∶疮干者，宜退火止用轻剂，荆
芥、升麻、干葛之类是也。更有所谓陷伏倒靥者，其形略似，其症不同陷伏者，有因胃
本虚弱，不能使阳气以副荣卫，故出而无气血以应之，是欲出而复没，斑晕白色，或
黑，大便自利，小便不赤而不能食，或倦，或呕，四肢散厥，因内虚不能由者，此为陷
伏也。当用辛温之药，令其胃暖，荣卫无滞，自然出矣。如理中汤、活血散、木香异
攻散之类，皆可审投也。倒靥者，痘点既出，外被风寒所感，致使肌窍复闭，气血凝
涩，身痛微厥，大小便秘，痘痕不长，或黑紫，或平润是皆所谓倒靥也，宜急温肌，发
散风寒，如参苏饮、小柴胡汤，或加紫草、蝉蜕、僵蚕之类，温散风寒，则热气自然流
通，而痘必复长矣。更有热邪干滞，二便不通，腹满喘急，热甚谵语，黑陷焦紫者，治
宜下之。下后而气冷寒战者，凶；气若温平者，吉；甚若黑陷干枯而舌黑者，不治。至
于痘之黑点者，是毒不宜散也。盖血载毒，上参阳位，阳不足，阴往乘之，气不蓄血，
血亦不荣，渐致枯黑，宜以保元汤加归、芎、肉桂，提补其气，则毒发而变黄。若不
为鼓舞宣发，则火郁在内，譬诸炒豆，火微则黄而熟，以其存润势也。火盛则暴而黑，
其火性猛烈，莫之御也。火久则焦而槁，湿润之体无可复矣。
痘之名塌者，其形平而不窜，因气血不能交驰而鼎峻之功已亏，真元不得翕聚，而
充灌之势不至，故平塌而不饱满也。更名之陷者，其体深而危，因元气亏损，而邪火侵
侮于中，囊壳溃烂而真浆未灌于内，故坑陷而不能振垒也。此总是元气虚弱，不能拘制
其血，以载毒出表，遂使血离而不附，气亦散而不聚，虽起而不饱满，故名为陷。气虚
极而不能拘血，血不受拘而载毒以出，故名为塌，塌与陷似同而实异，陷则中陷而不
起，根窠犹在；塌则平塌无痕，或有痕而无根也。有为陷塌者，未满而塌也。有为倒塌
者，满而后塌也。有为顶陷者，根窠既立，真元虚弱，不能续其后来之气，锐势萎顿
也。有为黑陷者，是气不能蓄血以养，且兼毒滞而血干也。有为血陷者，是卫气不足，
而荣血过盈，气不拘化成浆而中止也。有为白陷者，气既不足，血因衰弱，气血两亏，
毒无由解，故久则陷而为白也。有为灰陷者，气血衰弱，内外两亏，外如蚕种，空壳
无浆，或虚有根窠，内含清水而为不治也。然丹溪曰∶炉灰白色者，人果知为虚寒矣。
又须看其静者，怯者，果为寒论。如勇者。燥者， 发者，此又当为热看，不可概例
也。有为毒陷者，是血与毒相逐，气弱不能拘化，乃凝结而不荣，干枯而不润也。有为
倒陷者，七日之后，根窠发足，浆满光荣，或因风寒乘虚外袭，气血凝泣，毒乃内攻，
或吐泻烦渴，气血津枯，脓浆退去，毒因内陷。总之，未有不因于虚也。更宜于虚之
中，察其皮薄色白，方为真虚，若囊浓色苍，此为毒瓦斯壅遏，不能外达，根不松发而
名为毒绊耳。若从虚治，益增塌陷。至于黑者，乃火之死也。盖色之繁红焦紫者，由于
火之所致，然力穷乃止，故热则红，滞则焦，极则黑，犹之火活则色红，火死则色
黑，曰变黑归肾者，言毒瓦斯归肾也。
凡内而不出者，谓之伏。外而复入者，谓之陷。痘疮有黑陷者，其症有四，一则因
感受风寒肌窍闭塞，血凝不行而黑陷者，必身体疼痛，四肢微厥，斑点不长，或变黑
色，或青紫瘾疹者，此为倒伏也，治宜温肌发散，则寒邪自去，热气复行，其斑自长
矣。二则因毒瓦斯大盛，内外蒸荣，是以毒复入里而黑陷者，必心烦狂燥，气喘妄言，如
见鬼神，大小便闭，渴而腹胀者，此为倒陷伏也，治宜大利之，以泻膀胱之毒，令其阳
气复还，脾胃温暖。然服后而身热气温能食者，是脾强胜肾，毒虽盛而里气强，足以续
其后来，故能驱毒达外，其陷者，当自复出，可治之兆。若加以寒战而身冷汗出，耳
尻反热者，死。三则因内虚，而不能使阳气以副荣卫，是以出而复没，其点白色，或有
黑色者，其人必不能乳食，大便自利，或呕，或厥，盖此是胃虚内弱而不能出，乃为
陷伏也，治宜温中之剂，令其胃暖而荣卫复行，则当自出矣。更有因误下之后，是以毒
气入里而黑陷者，亦宜先为温养其里，后以桂枝、葛根疏解其表，则自出矣。四则因被
房室等秽恶气冲触而黑陷者，急宜紫草、僵蚕、当归、红花、穿山甲、蝉蜕、甘草、生
地之类，外用熏解可也。然按古方，凡治黑陷俱用穿山甲，取其穿肠透膜善走窜也。用
人牙者，牙乃骨余，可发肾毒也。但二物借为向导施治，则若单用之无益也。然有用烧
人粪者，以其善解疫毒，痘乃时疫所感，故用之加入发表和中，解毒汤中最妙。
伏者，毒蓄于里而不出也。陷者，毒出而复陷入也。然伏唯一症，而陷则有数种。
如伏候见于见形之时者，其人疮出之后，热不少减，烦渴闷躁，此可见有伏毒而未尽出
也。陷则见于见形之后。如血渐干而变黑者，谓之黑陷。如浆水未成，破损痒塌者，
谓之倒陷。如脓成复化为水，不肯结痂者，谓倒靥。倒靥者，亦陷之类也。如疮黑色
者，皆谓之黑陷，然黑陷谓之归肾者，以肾属水而色黑，为真脏色见也，故云不治。然
此者，岂独肾旺而夺权哉！本出血气大亏，不能逐毒于表而枯萎耳。何世妄谓肾实，必
欲泻而使之更虚！不知人之一身，大言阴与阳，小言心与肾，即所谓真水真火也。痘疮
之火发于中，赖此一点真水以制其冲，苟或泻之，则火无所制，本先拔矣。况血之干
者，色必黑，出于火者，色亦黑，故《经》曰∶火发而曛昧。本已水虚火实为害矣，岂
堪复谓肾实泻水为事耶！然紫黑陷者，乃血势干滞，气不能以营运，尚论虚中有余之
症，急治犹可复活，若陷至灰白者，乃元气衰败而不能以起发，血亦离散而不得以通
贯，系不足之中更不足也，故多难疗，若倒靥而痘出血不止者，名回阳泉，如犯胸胁之
地，十难救一，惟在他处者，速觅胭脂胚加血竭一钱，俱烧存性，点上，其血收干者，
为愈。
水如果没有土的制约就会泛滥，土质坚实则水流顺畅，这是自然的道理。土是万物的母亲，而痘疮的起发、灌浆和结痂成实，都依赖脾胃化生之源的生发作用。如果先天元气薄弱，脾土受损，那么负责传导排泄的器官（脾胃）失职，生化之机衰退，气血无法充分充盈灌注，于是土溃水浮，水泡随之发生。然而一旦发泡，痘囊就会空虚而不饱满。有的因为气机过盛而形成水泡，这应当说是邪气过于冲击而导致起泡，难道是正气充实，不能逐毒化浆，反而导致水泡臭痒的祸患吗？有的根据部位所属的五行来推断，虽然似乎有理，但未免多歧路，不切合治法。总之，头部是元首之尊，胸部是受气之地，颈部是出入之所，背部是五脏俞穴所属之处，正常的痘疮尚且嫌多，何况水泡呢？只有在手足部位，就像士兵卒伍那样卑贱，少见且不造成危害，但这也是脾虚的确切征象。如果蔓延到被单交片处，则是恶候，是臭痒的开始。以往有各种疮疡或破伤未痊愈，或刚痊愈斑痕娇嫩，痘出簇集而化为水泡的，是由外因而致，并非内病，没有危害。按照古论，水泡的恶劣程度与黑陷相似，外出内入，形势虽不同，但毒气滞留为害是一样的。盖因毒瓦斯猛烈，反成郁遏，极则冲突平陷之处，即郁遏之处。水泡所在之处，即是冲突之所。热毒内伏，驱逐津液先行罢了。内治宜逐毒松血，外用银针刺破，放出紫血，用芫荽酒调宫粉涂抹。
痘色干红，红后必变紫，紫必变黑，黑必变枯陷，这是血热毒滞而行，乃内热渐变的必然机理。治疗者，在干红之时，急宜解散凉血，退热清利，此时痘顶虽平陷，不可以气虚而用人参补剂，否则，气盛而血愈干涸了。丹溪说：疮干者，宜退火止用轻剂，荆芥、升麻、干葛之类是也。更有所谓陷伏倒靥者，其形略似，其症不同。陷伏者，有因胃本虚弱，不能使阳气以副荣卫，故出而无气血以应之，是欲出而复没，斑晕白色，或黑，大便自利，小便不赤而不能食，或倦，或呕，四肢散厥，因内虚不能由者，此为陷伏也。当用辛温之药，令其胃暖，荣卫无滞，自然出矣。如理中汤、活血散、木香异攻散之类，皆可审投也。倒靥者，痘点既出，外被风寒所感，致使肌窍复闭，气血凝涩，身痛微厥，大小便秘，痘痕不长，或黑紫，或平润是皆所谓倒靥也，宜急温肌，发散风寒，如参苏饮、小柴胡汤，或加紫草、蝉蜕、僵蚕之类，温散风寒，则热气自然流通，而痘必复长矣。更有热邪干滞，二便不通，腹满喘急，热甚谵语，黑陷焦紫者，治宜下之。下后而气冷寒战者，凶；气若温平者，吉；甚若黑陷干枯而舌黑者，不治。至于痘之黑点者，是毒不宜散也。盖血载毒，上参阳位，阳不足，阴往乘之，气不蓄血，血亦不荣，渐致枯黑，宜以保元汤加归、芎、肉桂，提补其气，则毒发而变黄。若不為鼓舞宣发，则火郁在内，譬诸炒豆，火微则黄而熟，以其存润势也。火盛则暴而黑，其火性猛烈，莫之御也。火久则焦而槁，湿润之体无可复矣。
痘之名塌者，其形平而不窜，因气血不能交驰而鼎峻之功已亏，真元不得翕聚，而充灌之势不至，故平塌而不饱满也。更名之陷者，其体深而危，因元气亏损，而邪火侵侮于中，囊壳溃烂而真浆未灌于内，故坑陷而不能振垒也。此总是元气虚弱，不能拘制其血，以载毒出表，遂使血离而不附，气亦散而不聚，虽起而不饱满，故名为陷。气虚极而不能拘血，血不受拘而载毒以出，故名为塌，塌与陷似同而实异，陷则中陷而不起，根窠犹在；塌则平塌无痕，或有痕而无根也。有为陷塌者，未满而塌也。有为倒塌者，满而后塌也。有为顶陷者，根窠既立，真元虚弱，不能续其后来之气，锐势萎顿也。有为黑陷者，是气不能蓄血以养，且兼毒滞而血干也。有为血陷者，是卫气不足，而荣血过盈，气不拘化成浆而中止也。有为白陷者，气既不足，血因衰弱，气血两亏，毒无由解，故久则陷而为白也。有为灰陷者，气血衰弱，内外两亏，外如蚕种，空壳无浆，或虚有根窠，内含清水而为不治也。然丹溪曰：炉灰白色者，人果知为虚寒矣。又须看其静者，怯者，果为寒论。如勇者。燥者， 发者，此又当为热看，不可概例也。有为毒陷者，是血与毒相逐，气弱不能拘化，乃凝结而不荣，干枯而不润也。有为倒陷者，七日之后，根窠发足，浆满光荣，或因风寒乘虚外袭，气血凝泣，毒乃内攻，或吐泻烦渴，气血津枯，脓浆退去，毒因内陷。总之，未有不因于虚也。更宜于虚之中，察其皮薄色白，方为真虚，若囊浓色苍，此为毒瓦斯壅遏，不能外达，根不松发而名为毒绊耳。若从虚治，益增塌陷。至于黑者，乃火之死也。盖色之繁红焦紫者，由于火之所致，然力穷乃止，故热则红，滞则焦，极则黑，犹之火活则色红，火死则色黑，曰变黑归肾者，言毒瓦斯归肾也。
凡内而不出者，谓之伏。外而复入者，谓之陷。痘疮有黑陷者，其症有四，一则因感受风寒肌窍闭塞，血凝不行而黑陷者，必身体疼痛，四肢微厥，斑点不长，或变黑色，或青紫瘾疹者，此为倒伏也，治宜温肌发散，则寒邪自去，热气复行，其斑自长矣。二则因毒瓦斯大盛，内外蒸荣，是以毒复入里而黑陷者，必心烦狂燥，气喘妄言，如见鬼神，大小便闭，渴而腹胀者，此为倒陷伏也，治宜大利之，以泻膀胱之毒，令其阳气复还，脾胃温暖。然服后而身热气温能食者，是脾强胜肾，毒虽盛而里气强，足以续其后来，故能驱毒达外，其陷者，当自复出，可治之兆。若加以寒战而身冷汗出，耳尻反热者，死。三则因内虚，而不能使阳气以副荣卫，是以出而复没，其点白色，或有黑色者，其人必不能乳食，大便自利，或呕，或厥，盖此是胃虚内弱而不能出，乃为陷伏也，治宜温中之剂，令其胃暖而荣卫复行，则当自出矣。更有因误下之后，是以毒气入里而黑陷者，亦宜先为温养其里，后以桂枝、葛根疏解其表，则自出矣。四则因被房室等秽恶气冲触而黑陷者，急宜紫草、僵蚕、当归、红花、穿山甲、蝉蜕、甘草、生地之类，外用熏解可也。然按古方，凡治黑陷俱用穿山甲，取其穿肠透膜善走窜也。用人牙者，牙乃骨余，可发肾毒也。但二物借为向导施治，则若单用之无益也。然有用烧人粪者，以其善解疫毒，痘乃时疫所感，故用之加入发表和中，解毒汤中最妙。
伏者，毒蓄于里而不出也。陷者，毒出而复陷入也。然伏唯一症，而陷则有数种。如伏候见于见形之时者，其人疮出之后，热不少减，烦渴闷躁，此可见有伏毒而未尽出也。陷则见于见形之后。如血渐干而变黑者，谓之黑陷。如浆水未成，破损痒塌者，谓之倒陷。如脓成复化为水，不肯结痂者，谓倒靥。倒靥者，亦陷之类也。如疮黑色者，皆谓之黑陷，然黑陷谓之归肾者，以肾属水而色黑，为真脏色见也，故云不治。然此者，岂独肾旺而夺权哉！本出血气大亏，不能逐毒于表而枯萎耳。何世妄谓肾实，必欲泻而使之更虚！不知人之一身，大言阴与阳，小言心与肾，即所谓真水真火也。痘疮之火发于中，赖此一点真水以制其冲，苟或泻之，则火无所制，本先拔矣。况血之干者，色必黑，出于火者，色亦黑，故《经》曰∶火发而曛昧。本已水虚火实为害矣，岂堪复谓肾实泻水为事耶！然紫黑陷者，乃血势干滞，气不能以营运，尚论虚中有余之症，急治犹可复活，若陷至灰白者，乃元气衰败而不能以起发，血亦离散而不得以通贯，系不足之中更不足也，故多难疗，若倒靥而痘出血不止者，名回阳泉，如犯胸胁之地，十难救一，惟在他处者，速觅胭脂胚加血竭一钱，俱烧存性，点上，其血收干者，为愈。
Water without earth will burst its banks; if the earth is solid, the flow is smooth. This is the natural principle. Earth is the mother of all things, and the emergence, filling, and hardening of smallpox lesions all rely on the generation and development derived from the Spleen and Stomach. If congenital vitality is weak and the Spleen Earth is damaged, the official responsible for transportation and excretion (Spleen and Stomach) fails in its duty, and the mechanism of transformation and production becomes diluted. Qi and Blood cannot fully fill and irrigate, causing the earth to collapse and water to float, leading to the eruption of blisters. However, once a blister erupts, the pustule sac becomes empty and not full. Some blisters form due to excessive Qi; this should be described as pathogenic Qi excessively impacting and causing blistering. Could it be that when Zheng Qi (Upright Qi) is solid, it cannot expel toxins and transform them into pus, instead causing the disaster of foul-smelling, itchy blisters? Some judge based on the Five Elements associated with body locations; although this seems reasonable, it leads to many divergent paths and does not fit treatment methods well. In short, the head is the dignity of the chief, the chest is the place receiving Qi, the neck is the passage of entry and exit, and the back belongs to the five Shu points. Even normal smallpox lesions are considered too numerous in these areas, let alone blisters! Only on the hands and feet, which are like lowly soldiers, are they rarely seen and harmless, yet this is also a clear sign of Spleen deficiency. If they spread to cover sheets or patches, it is an ominous sign, indicating the onset of foul smell and itching. Previously, there were cases where various sores or broken injuries had not healed, or newly healed spots were tender, and smallpox erupted in clusters turning into blisters; these were caused by external factors and were not internal diseases, thus posing no harm. According to ancient theories, the malignancy of blisters is similar to black sinking. Although the direction of expulsion (outward vs. inward) differs, the harm caused by toxin stagnation is the same. The toxic vapors are fierce, leading to depression and obstruction; at extremes, they conflict with flat or sunken areas, which are sites of obstruction. Blister sites are sites of conflict. Internal heat toxins lie dormant, driving out body fluids first. Internally, one should expel toxins and loosen blood stasis; externally, prick with a silver needle to release purple blood, then apply Gong Fen (Lead Carbonate) mixed with Wan Su Jiu (Coriander Wine).
When the smallpox color is dry red, it must turn purple after red, black after purple, and withered/sunken after black. This progression occurs due to blood heat and toxin stagnation, representing a certain mechanism of gradual internal heat change. The practitioner, during the dry red stage, should urgently resolve the exterior, cool the blood, reduce fever, and promote clearing and draining. Although the pustule crown may be flat or sunken, do not use Ginseng tonics for Qi deficiency; otherwise, excessive Qi will cause the blood to become even more dried up. Danxi said: For dry sores, one should reduce fire using only mild agents, such as Jing Jie (Schizonepeta), Sheng Ma (Cimicifuga), and Gan Ge (Pueraria). There is also what is called "Xian Fu" (Sunken/Fixed) and "Dao Ye" (Reversed Crusting). Their shapes are slightly similar, but symptoms differ. Xian Fu cases arise because the Stomach is originally weak, unable to allow Yang Qi to assist Ying and Wei (Defensive and Nutritive Qi), so eruptions lack Qi and Blood to respond, appearing and then disappearing. Spots may be white or black, stool is loose, urine is not dark, appetite is lost, fatigue or vomiting may occur, and limbs are cold. Due to internal deficiency preventing proper eruption, this is Xian Fu. One should use acrid-warm medicines to warm the Stomach, ensuring Ying and Wei flow without stagnation, allowing natural eruption. Formulas like Lizhong Tang (Regulate the Middle Decoction), Huoxue San (Invigorate Blood Powder), or Muxiang Yigong San (Aucklandia Overcoming Attack Powder) can be carefully selected. Dao Ye occurs when smallpox spots have emerged but are affected by external Wind-Cold, causing skin pores to close again, leading to Qi and Blood coagulation and stagnation. Symptoms include body pain, slight coldness in limbs, constipation of both bowels and bladder, stalled growth of lesions, or black/purple or flat/smooth appearance. These are all called Dao Ye. Urgently warm the muscles and disperse Wind-Cold using formulas like Shen Su Yin (Ginseng Perilla Drink) or Xiao Chaihu Tang (Minor Bupleurum Decoction), possibly adding Zi Cao (Arnebia), Chan Tui (Cicada Slough), or Jiang Can (Bombyx Batryticatus). Warming and dispersing Wind-Cold allows heat Qi to flow naturally, and smallpox will regrow. Furthermore, if Heat Evil causes dryness and stagnation with blocked urination and defecation, abdominal distension, panting, urgency, severe heat with delirium, and black sinking with scorched purple color, treatment should involve purgation. After purgation, if Qi is cold with chills, it is ominous; if Qi is warm and balanced, it is auspicious; if severely black, sunken, withered, and the tongue is black, it is untreatable. Regarding black spots on smallpox, the toxin should not be dispersed. Blood carries toxins upward to Yang positions; if Yang is insufficient, Yin takes advantage. Qi fails to retain blood, and blood fails to nourish, gradually becoming withered and black. Use Baoyuan Tang (Protect Origin Decoction) added with Dang Gui (Angelica Sinensis), Chuan Xiong (Ligusticum), and Rou Gui (Cinnamon Bark) to lift and tonify Qi, causing toxins to emerge and turn yellow. If not encouraged and released, Fire Depression remains inside. Like roasting beans, low fire makes them yellow and cooked due to retained moisture; high fire makes them violently black, as its nature is fierce and uncontrollable. Prolonged fire chars and dries them, leaving no possibility of restoring moisture.
Smallpox named "Ta" (Collapse) has a flat shape without protrusion because Qi and Blood cannot interact vigorously, the功 (merit/function) of formation is deficient, Zhen Yuan (True Origin) cannot gather, and the momentum of filling does not arrive, resulting in flat collapse and lack of fullness. Named "Xian" (Sink) refers to a deep and dangerous condition due to Yuan Qi depletion and evil Fire invading internally. The sac shell ulcerates, and true pus does not fill inside, causing pit-like sinking unable to raise defenses. This is always due to weak Yuan Qi failing to control blood to carry toxins to the surface, causing blood to separate and Qi to scatter. Though raised, it is not full, hence named Xian. Extreme Qi deficiency fails to constrain blood; unconstrained blood carries toxins out, hence named Ta. Ta and Xian seem similar but are actually different. Xian sinks deeply without rising, though the root base remains; Ta is flat with no trace, or with traces but no root. There are cases of Xian Ta (sunken and collapsed) before fullness; Dao Ta (fallen and collapsed) after fullness; Ding Xian (crown sinking) where the root base is established but Yuan Qi is weak, unable to sustain subsequent Qi, causing sharp momentum to wither; Hei Xian (black sinking) where Qi cannot store blood to nourish, combined with toxin stagnation and dried blood; Xue Xian (blood sinking) where Wei Qi is insufficient and Ying Blood is excessive, Qi fails to constrain and transform into pus, stopping midway; Bai Xian (white sinking) where Qi is insufficient, Blood is weak due to decline, both Qi and Blood are deficient, toxins have no way to resolve, eventually sinking to become white; Hui Xian (ash sinking) where Qi and Blood are weak, internal and external deficiency exists, externally resembling silkworm eggs, empty shells without pus, or hollow with root bases containing clear water, which is untreatable. Danxi said: Ash-white color indicates deficiency-cold. Observe if the patient is quiet or timid, confirming cold syndrome. If brave, dry, or inflamed, consider heat syndrome; do not generalize. You Du Xian (toxin sinking) occurs when Blood and toxins chase each other, Qi is weak and cannot constrain/transform, leading to coagulation without nourishment, dryness without moisture. Dao Xian (reversed sinking) occurs after seven days when root bases are sufficient and pus is full and glorious, but due to Wind-Cold attacking emptiness externally, Qi and Blood coagulate, toxins attack internally, or vomiting/diarrhea cause thirst and exhaustion of Qi/Blood/fluids, pus recedes, and toxins sink internally. In summary, it is never without deficiency. Further examine within deficiency: thin skin and white color indicate true deficiency. If the sac is thick and color dark, this is toxic vapor obstruction unable to reach the exterior, roots not loosened, named "Toxin Binding." Treating as deficiency increases collapse. Black represents the death of Fire. Colors ranging from bright red to scorched purple result from Fire. When force is exhausted, it stops. Thus, heat is red, stagnation is scorched, extreme is black. Just as living fire is red and dead fire is black, "turning black returning to Kidney" means toxic vapors return to the Kidney.
Anything internal and not emerging is called "Fu" (Hidden). Anything external and re-entering is called "Xian" (Sink). Smallpox with black sinking has four syndromes. First, due to contracting Wind-Cold closing skin pores, blood coagulates and does not flow, causing black sinking. Symptoms must include body pain, slight coldness in limbs, spots not growing, or turning black/blue-purple macules. This is Dao Fu (Reversed Hidden). Treatment should warm muscles and disperse, removing Cold Evil so Heat Qi flows again, and spots grow. Second, due to excessive toxic vapors steaming internally and externally, toxins re-enter the interior causing black sinking. Symptoms must include mental restlessness, mania, panting, delirium seeing ghosts, blocked urination/defecation, thirst, and abdominal distension. This is Dao Xian Fu (Reversed Sink Hidden). Treatment should strongly drain to expel bladder toxins, restoring Yang Qi and warming Spleen/Stomach. If after taking medicine, body heat returns, warmth improves, and appetite returns, Spleen overcomes Kidney. Although toxins are strong, interior Qi is strong enough to sustain later stages, driving toxins outward. Sunken spots should re-emerge, a sign of treatability. If accompanied by chills, cold sweat, and heat in ears/buttocks, death ensues. Third, due to internal deficiency failing to allow Yang Qi to assist Ying/Wei, eruptions appear and disappear. Spots are white or black. Patient cannot eat/drink, stool is loose, vomiting or coldness may occur. This is Stomach deficiency/internal weakness failing to erupt, called Xian Fu. Treatment should use warming middle agents to warm Stomach and restore Ying/Wei flow, allowing natural eruption. If caused by erroneous purgation leading to toxin entering interior and black sinking, first warm/nourish the interior, then use Gui Zhi (Cinnamon Twig) and Ge Gen (Pueraria) to release the exterior, allowing natural eruption. Fourth, due to exposure to foul odors from sexual activity etc., causing black sinking. Urgently use Zi Cao, Jiang Can, Dang Gui, Hong Hua, Shan Jia (Pangolin Scale), Chan Tui, Gan Cao (Licorice), and Sheng Di (Rehmannia), applying externally for fumigation and resolution. Ancient formulas for black sinking all use Pangolin Scale for its ability to penetrate intestines/membranes and move freely. Using Human Teeth (Ren Ya), being bone residue, can stimulate Kidney toxins. But these two substances serve only as guides; using them alone is useless. Some use burned human feces because it resolves epidemic toxins well. Since smallpox is contracted from seasonal epidemics, adding it to formulas that release exterior, harmonize middle, and detoxify is excellent.
Fu (Hidden) means toxins stored internally do not emerge. Xian (Sink) means toxins emerge then sink back. Fu presents as one syndrome, while Xian has several types. If Fu signs appear during the manifestation stage, after sores emerge, heat does not decrease, with irritability, thirst, and restlessness, visible latent toxins have not fully emerged. Xian appears after the manifestation stage. If blood gradually dries and turns black, it is called Hei Xian (Black Sinking). If pus fluid is not formed,破损 (broken/damaged), itchy, and collapsed, it is called Dao Xian (Reversed Sinking). If pus forms but turns back to water, refusing to scab, it is called Dao Ye (Reversed Crusting). Dao Ye is also a type of Xian. Any black sores are called Hei Xian. Hei Xian is called "Returning to Kidney" because Kidney belongs to Water and color is black, representing the appearance of the True Organ color, hence deemed untreatable. However, is this solely due to Kidney excess usurping power? Fundamentally, it is massive loss of Qi and Blood, inability to expel toxins to the surface, leading to withering. Why do people wrongly claim Kidney excess and insist on draining to make it more deficient? They do not know that the human body, broadly speaking Yin and Yang, narrowly speaking Heart and Kidney, constitutes True Water and True Fire. Smallpox Fire originates in the middle, relying on this bit of True Water to restrain its surge. If drained, Fire has no restraint, and the root is pulled out first. Moreover, dried blood must be black; fire-originated color is also black. Thus, the Classic says: "Fire erupts and obscures clarity." The root is already Water Deficient and Fire Excess, causing harm; how can one further claim Kidney Excess and drain Water? Purple-black sinking is due to blood momentum being dry and stagnant, Qi unable to circulate. Discussing deficiency with surplus, urgent treatment can still revive. If sinking reaches ash-white, Yuan Qi has failed and cannot rise, blood is scattered and cannot connect, representing insufficiency within insufficiency, making it difficult to treat. If reversed crusting involves unceasing bleeding from smallpox, named Hui Yang Quan (Returning Yang Spring), if it affects the chest/hypochondrium, ten cases save one; if elsewhere, quickly find Yan Zhi Pei (Vermilion Embryo) plus Xue Jie (Dragon's Blood) one qian, calcine until charred but preserve nature, apply to the spot. If bleeding stops and dries, it is cured.