此又方之不可执言也。故凡补虚之法，但当明其阴阳、升降、寒热、温凉之性，精中有气、气中有精之因。
且凡上焦阳气不足者，必下陷于肾也，当取之至阴之下；下焦真阴不足者，多飞越于上也，可不引之归原
乎？所以治必求本，方为尽善。
凡虚损既成，不补将何以复？而有不能服人参、熟地诸药者，此为虚不受补，何以望生？若以失血后嗽
不止、痰多甚者，此脾肺虚极，饮食无能化血，而随食成痰。此虽非血，而实血之类也。经曰∶白血出者死。
有不得左右眠，而认一边难转者，此其阴阳之气有所偏竭而然，多不可治。若虚症别无邪热，而谵妄失伦，
此心脏之败，神去之兆也，必死。劳嗽喑哑，声不能出，此肺脏之败也，必死。劳损肌肉脱尽者，此脾脏之
败也，必死。筋为罢极之本，病虚损而筋骨疼痛，若痛至极，不可忍者，乃血竭不能养筋，此肝脏之败也，
必死。劳损既久，再大便泄泻不能禁止者，此肾脏之败也。必死。
《治法纲》曰∶内伤发热，则从内自汗出，六脉微弱，或右手气口大三倍于人迎，按之无力，浑身酸
软或痛，倦于言，动怠惰，属内伤元气虚，宜补中益气汤加减。发热甚于午后，遗滑，或咳嗽有红，皮毛枯
槁，属阴虚，热久则变为骨蒸劳极，治法如劳瘵条下。又有伤食发热，恶寒头痛，呕恶，胸中饱闷而痛胀，
右寸关俱紧而滑，左脉弦急，属内伤饮食，外感风寒之热，先宜解散，后消导和中。又有发热昼重夜轻，
口中无味，阳虚也；午后发热，夜半则止，阴虚也。阳虚责之
胃，阴虚则之肾。盖饥饱伤胃，房劳伤肾。以药论之，甘温补气，甘寒滋阴。若气血两虚，只补其气，
阳旺生阴也。
东垣曰∶昼则发热，夜则安静，是阳气自旺于阳分也。夜则发热，昼则安静，是阳气下陷入阴中也，
名曰热入血室。昼则发热烦躁，夜亦发热烦躁，是重阳无阴也，当亟泻其阳，峻补其阴。
王冰曰∶病热而脉安，按之不鼓，乃寒盛格阳而致之，非热也。形症是寒，按之脉气鼓击于手下者，
此为热盛拒阴，非寒也。
赵养葵曰∶病热作渴，饮冷便闭，此属实热，人皆知之。或恶寒发热，引衣蜷卧，四肢逆冷，大便
清利，此属真寒，人亦易知。至于烦扰狂越，不欲近衣，欲坐卧泥水中，此属假热之证。甚者烦极发躁，
渴饮不绝，舌如芒刺，两唇燥裂，面如涂朱，身如焚燎，足心如烙，吐痰如涌，喘急，大便闭结，小便淋沥，
三部脉洪大而无伦。当是时也，却似承气症，承气入口即毙；却似白虎症，白虎下咽即亡。若用二丸，缓不
济事。急以加减八味丸料一斤，内肉桂一两，以水煎五六碗，冰冷与饮，诸证自退。翌日必畏寒脉沉，是无
火也，当补其阳，急以附子八味丸料，煎服自愈。此证与脉气俱变其常，而不以常法治之者也。若有产后及
大失血后，阴血暴伤，必大发热，亦名阴虚发热，若以凉药正治，立毙。正所谓象白虎证，服白虎必死。须
用独参汤，或当归补血汤，使无形生出，此阳生阴长之妙。或问∶气虚、血虚均是内伤，何以辨之？曰∶
阴虚者面必赤，无根之火戴于上也。若阳症，火入于内，面必不赤。其口渴者，肾水干枯，引水自救也。但
口虽渴而舌必滑，脉虽数而尺必无力，甚者尺虽洪数，而按之不鼓，此为辨耳。戴复庵云∶服凉药而脉数者
火郁，宜升补。
王节斋曰∶世间发热。类伤寒者数种，治各不同，外感、内伤乃大关键。张仲景论伤寒、伤风，此外感
也。风寒自表入里，故宜发表，以解散之，此麻、桂二方之义也。以其感于冬春寒冷，药用辛热胜寒。若时
非寒令，则药当变矣。如春温之月，则药当以辛凉；夏暑之月，则药当以甘苦寒。故云∶伤寒不即病，至春
变温，至夏变热。而其治法，必因时而有异也。又有一种冬温之病，谓之非其时而有其气，冬寒也而反病温。
此天时不正，阳气反泄，用药不可温热。又有一种时行寒疫，却在温暖之时，而寒反为病。此亦天时不正，
阴气反逆，用药不可寒凉。又有一种天行温疫热病，多发于春夏之交，沿门阖境相同。此天地之厉气，当随
时令，参运气而施治，宜用刘河间辛凉甘苦寒之药，以清热解毒。以上诸症，皆外感天地之邪气也。
若夫饮食劳倦，内伤乎元气，此真阳下陷，内生虚热。故东垣发补中益气之论，用人参、黄 等甘温之药
，以补其气而提其下陷，此用气药以补其气之不足者也。
又若劳心好色，内伤真阴，阴血既伤，则阳气偏胜而变为火矣，是为阴虚火旺劳瘵之证。故丹溪发阳
有余阴不足之论，用四物汤而黄柏、知母，补其阴而火自降，此用血药以补血之不足者也。益气、补阴，皆
内伤症也。一则因阳气之下陷以升提之，一则因阳火之上升而滋其阴以降下之，一升一降，迥然不同矣。
又有夏月伤暑之病，虽属外感，却类内伤，与伤寒大异。盖寒伤形，寒邪客表，有余之症，故宜汗之；
暑伤气，元气为热气所伤，为耗散不足之症，故宜补之，东垣所谓益气清暑是也。
又有因时暑热，而过食冷物，以伤其内；或过取凉风，以
伤其外。此则非暑伤人，乃因暑而自致之病。治宜辛热解表，或辛温理中之药，却与伤寒治法相类者也。
凡此数证，外形相似，而实有不同，治法多端，而不可或谬。盖外感之与内伤，寒病之与热病，气
虚之与血虚，如冰炭相反，治之若差，则轻病必重，重病必死矣，可不谨哉。
张景岳曰∶阴虚阳胜，或阴阳俱虚，为寒热往来者，此以真阴不足，总属虚损之病也。然其阴阳微甚，
亦所当辨。如昼热夜静，此阳邪旺于阳分，阳有余也；昼静夜热，阳邪陷入阴中，阴不足也。其有昼夜俱热，
兼烦躁多汗，而本非外感，此症虽曰重阳，而实则阴虚之极也。又有或见溏泄，或上见呕恶，而潮热夜热者，
此元气无根，阳虚之病也。大都阳实宜泻阳，泻阳者宜用苦寒；阴虚者宜补阴，补阴者宜用甘凉。惟阳虚一
证，则身虽有热，大忌寒凉，此则人多不识也。
又有寒邪抑伏经络，而为寒为热，此似疟非疟之类也，治法虽宜表散，然邪气得以久留者，必其元气
之虚，而正不胜邪。故凡治此者，皆当以兼补气血为主。若病久元气大虚，而寒热不退者，但当单培元气，
不必兼散。察其阴阳，择而用之，若果阳虚，非用温补不可。
又曰∶凡寒自内生者，必由脏及表，所以战栗憎寒，或厥逆拘挛。总之热者多实，寒者多虚，故凡治
寒证者，当兼察其虚，而仍察其脏，此不易之法也。
这又说明了方剂的使用不能拘泥于成法。所以凡是补虚的方法，只应当明确其阴阳、升降、寒热、温凉的药性，以及精中有气、气中有精的机理。
况且凡是上焦阳气不足的，必然下陷于肾，应当取用至阴之下的药物；下焦真阴不足的，多会上越于上，难道不可以引导它回归本源吗？所以治疗必须求本，才算尽善尽美。
凡是虚损已经形成，如果不进行补益，靠什么来恢复呢？然而有的人不能服用人参、熟地黄等药物，这是因为“虚不受补”，这种情况下怎么指望能生存呢？如果是失血之后咳嗽不止、痰多严重的，这是脾肺极度虚弱，饮食无法转化为血液，反而随着食物变成痰。这虽然不是血，但实际上属于血的同类。医经说：“白血出者死。”
有的人无法左右侧卧，认为其中一边难以翻身，这是因为阴阳之气有所偏颇衰竭所致，大多不可治愈。如果虚证没有其他的邪热，却出现胡言乱语、失去常理，这是心脏功能败坏，神志离去的征兆，必定死亡。劳嗽导致声音嘶哑，声音发不出，这是肺脏功能败坏，必定死亡。劳损导致肌肉脱尽，这是脾脏功能败坏，必定死亡。筋是罢极（疲劳）的根本，患虚损病而筋骨疼痛，如果痛到极点，无法忍受，这是血竭不能滋养筋脉，肝脏功能败坏，必定死亡。劳损日久，再加上大便泄泻无法控制，这是肾脏功能败坏，必定死亡。
《治法纲》说：内伤发热，会从内部自然出汗，六脉微弱，或者右手气口脉比人迎脉大三倍，按之无力，浑身酸软或疼痛，疲倦不想说话，行动怠惰，属于内伤元气虚，适宜用补中益气汤加减。发热在午后加重，伴有遗精滑泄，或者咳嗽带血，皮毛枯槁，属于阴虚，热久则变为骨蒸劳极，治疗方法参照劳瘵条下的内容。又有因伤食引起的发热，恶寒头痛，呕吐恶心，胸中饱闷且胀痛，右寸关脉俱紧而滑，左脉弦急，属于内伤饮食，兼外感风寒之热，先宜解散表邪，后消导和中。又有发热昼重夜轻，口中无味，属于阳虚；午后发热，半夜停止，属于阴虚。阳虚责之于胃，阴虚责之于肾。大概饥饱损伤胃，房劳损伤肾。从药物理论来说，甘温补气，甘寒滋阴。如果气血两虚，只补气，阳气旺盛就能生阴。
李东垣说：白天发热，晚上安静，是阳气在阳分自旺。晚上发热，白天安静，是阳气下陷入阴中，名叫热入血室。白天发热烦躁，晚上也发热烦躁，是重阳无阴，应当紧急泻其阳，峻补其阴。
王冰说：患病发热而脉象看似正常，按之不鼓动有力，这是寒盛格阳所致，并非真热。形症表现为寒，但按之脉气鼓击于手下，这是热盛拒阴，并非真寒。
赵养葵说：患病发热口渴，想喝冷水且便秘，这属于实热，人们都知道。或者恶寒发热，拉着衣服蜷缩躺卧，四肢逆冷，大便清稀，这属于真寒，人们也容易知道。至于烦躁狂乱，不喜欢穿衣，想坐在泥水中，这属于假热证。严重的烦躁至极发躁，口渴饮水不停，舌如芒刺，两唇燥裂，面色如涂朱砂，身体如火烧燎，脚心像被烙铁烫过，吐痰如涌，喘急，大便闭结，小便淋沥，三部脉洪大而无伦次。在这个时候，看起来像承气汤证，但承气汤入口即毙；看起来像白虎汤证，白虎汤下咽即亡。如果用二妙丸之类，缓不济事。紧急使用加减八味丸料一斤，内加肉桂一两，用水煎五六碗，冰冷后饮用，诸证自退。第二天必定畏寒脉沉，这是无火，应当补其阳，紧急使用附子八味丸料，煎服自愈。此证与脉气都改变了常规，不能用常法治之。如果有产后及大失血后，阴血突然受伤，必定大发热，也叫阴虚发热，如果用凉药正治，立刻致死。正所谓象白虎证，服白虎必死。须用独参汤，或当归补血汤，使无形之气生出，这是阳生阴长的奥妙。有人问：气虚、血虚都是内伤，如何辨别？回答说：阴虚者面必赤，是无根之火戴于头上。如果是阳证，火入于内，面必不赤。那些口渴的，是肾水干枯，引水自救。只是口虽渴而舌必滑，脉虽数而尺部必无力，严重的尺部虽洪数，但按之不鼓动，这是辨别的要点。戴复庵说：服凉药而脉数的，是火郁，宜升补。
王节斋说：世间发热，类似伤寒的有好几种，治疗各不相同，外感、内伤是大关键。张仲景论述伤寒、伤风，这是外感。风寒从表入里，所以宜发表，以解散之，这是麻黄汤、桂枝汤二方的义理。因为感受于冬春寒冷，药用辛热胜寒。如果时非寒令，则药当变矣。如春温之月，则药当以辛凉；夏暑之月，则药当以甘苦寒。所以说：伤寒不立即发病，到春天变为温病，到夏天变为热病。而其治疗方法，必须因时而异。又有一种冬温的病，叫做非其时而有其气，冬天寒冷却反得温病。这是天时不正，阳气反泄，用药不可温热。又有一种时行寒疫，却在温暖之时，而寒反为病。这也是天时不正，阴气反逆，用药不可寒凉。又有一种天行温疫热病，多发于春夏之交，沿门阖境相同。这是天地之厉气，应当随时令，参运气而施治，适宜用刘河间辛凉甘苦寒之药，以清热解毒。以上诸症，都是外感天地之邪气。
如果是饮食劳倦，内伤乎元气，这是真阳下陷，内生虚热。所以李东垣提出补中益气之论，用人参、黄芪等甘温之药，以补其气而提其下陷，这是用气药以补其气之不足。
又如果是劳心好色，内伤真阴，阴血既伤，则阳气偏胜而变为火矣，这是阴虚火旺劳瘵之证。所以朱丹溪提出阳有余阴不足之论，用四物汤加黄柏、知母，补其阴而火自降，这是用血药以补血之不足。益气、补阴，都是内伤症。一则因阳气之下陷以升提之，一则因阳火之上升而滋其阴以降下之，一升一降，迥然不同。
又有夏季伤暑的病，虽属外感，却类内伤，与伤寒大异。盖寒伤形，寒邪客表，有余之症，所以宜汗之；暑伤气，元气为热气所伤，为耗散不足之症，所以宜补之，李东垣所谓益气清暑是也。
又有因时令暑热，而过食冷物，以伤其内；或过取凉风，以伤其外。这则不是暑伤人，乃因暑而自致之病。治疗宜辛热解表，或辛温理中之药，却与伤寒治法相类。
凡此数证，外形相似，而实有不同，治法多端，而不可或谬。盖外感之与内伤，寒病之与热病，气虚之与血虚，如冰炭相反，治之若差，则轻病必重，重病必死矣，可不谨慎吗？
张景岳说：阴虚阳胜，或阴阳俱虚，为寒热往来者，这是以真阴不足，总属虚损之病。然而其阴阳微甚，也应当辨别。如昼热夜静，这是阳邪旺于阳分，阳有余；昼静夜热，阳邪陷入阴中，阴不足。其有昼夜俱热，兼烦躁多汗，而本非外感，此症虽曰重阳，而实则阴虚之极。又有或见溏泄，或上见呕恶，而潮热夜热者，这是元气无根，阳虚之病。大都阳实宜泻阳，泻阳者宜用苦寒；阴虚者宜补阴，补阴者宜用甘凉。惟阳虚一证，则身虽有热，大忌寒凉，这是很多人不认识的地方。
又有寒邪抑伏经络，而为寒为热，这似疟非疟之类，治法虽宜表散，然邪气得以久留者，必其元气之虚，而正不胜邪。所以凡是治疗此病，都应当以兼补气血为主。如果病久元气大虚，而寒热不退者，只当单培元气，不必兼散。察其阴阳，择而用之，如果果真是阳虚，非用温补不可。
又说：凡寒自内生者，必由脏及表，所以战栗憎寒，或厥逆拘挛。总之热者多实，寒者多虚，所以凡是治疗寒证者，应当兼察其虚，而仍察其脏，这是不易之法。
This further illustrates that the application of prescriptions cannot be rigidly adhered to. Therefore, in all methods of tonifying deficiency, one must clearly understand the properties of Yin and Yang, ascending and descending, cold and heat, warm and cool, as well as the interdependence of essence containing Qi and Qi containing essence.
Furthermore, whenever there is a deficiency of Yang Qi in the Upper Jiao (Upper Burner), it inevitably sinks into the Kidney; thus, one should select herbs from the lowest Yin level. Conversely, when there is a deficiency of True Yin in the Lower Jiao, it often floats upward; therefore, is it not necessary to guide it back to its origin? Hence, treatment must seek the root cause to be perfect.
Once deficiency damage is established, without tonification, how can recovery be expected? However, for those who cannot tolerate herbs such as Renshen (Ginseng Radix) or Shudihuang (Rehmanniae Radix Praeparata), this is termed "deficiency unable to accept tonification" (Xu Bu Shou Bu). In such cases, how can survival be hoped for? If after blood loss, coughing persists without cessation and phlegm is excessive, this indicates extreme deficiency of the Spleen and Lung. Dietary intake fails to transform into blood and instead turns into phlegm with food consumption. Although this is not blood, it is essentially of the same category as blood. The Classics state: "If white blood is expelled, death ensues."
Some patients cannot lie on either side, finding it difficult to turn over in one direction; this results from an imbalance and exhaustion of Yin and Yang Qi, and is mostly incurable. If a deficiency syndrome presents with delirium and loss of reason, yet lacks other pathogenic heat, this signifies the failure of the Heart and the departure of Shen (Spirit); death is inevitable. In cases of consumptive cough leading to aphonia where voice cannot be produced, this indicates the failure of the Lung; death is inevitable. When consumptive disease leads to the complete wasting away of muscles, this indicates the failure of the Spleen; death is inevitable. Tendons are the root of fatigue (Ba Ji); if deficiency damage causes pain in tendons and bones, and the pain reaches an unbearable intensity, this is due to blood exhaustion failing to nourish the tendons, indicating the failure of the Liver; death is inevitable. After prolonged consumptive disease, if diarrhea becomes uncontrollable, this indicates the failure of the Kidney; death is inevitable.
*Zhi Fa Gang* states: Internal injury fever manifests with spontaneous sweating from within, weak pulses in all six positions, or the Qi Kou pulse on the right hand being three times larger than the Ying Keng pulse, feeling powerless upon pressure. The body feels sore or painful, there is fatigue in speech, and lethargy in movement. This belongs to internal injury of Yuan Qi (Original Qi) deficiency, and *Buzhong Yiqi Tang* (Spleen-Boosting Qi-Rescuing Decoction) with modifications is appropriate. Fever worsening in the afternoon, accompanied by seminal emission or slippery discharge, or coughing up blood, with dry and brittle skin and hair, belongs to Yin deficiency. Prolonged heat transforms into bone-steaming consumptive disease; the treatment method follows the section on Lao Zhai (Consumptive Disease). There is also fever caused by food stagnation, characterized by aversion to cold, headache, vomiting, nausea, chest fullness, distension, and pain. The Right Cun and Guan pulses are both tight and slippery, while the Left pulse is wiry and rapid. This belongs to internal injury from diet combined with external contraction of Wind-Cold heat. Initially, release the exterior; subsequently, resolve stagnation and harmonize the Middle Jiao. There is also fever that is severe during the day and light at night, with a tasteless mouth, belonging to Yang deficiency; fever in the afternoon ceasing at midnight belongs to Yin deficiency. Yang deficiency is attributed to the Stomach, while Yin deficiency is attributed to the Kidney. Generally, irregular eating harms the Stomach, and sexual excess harms the Kidney. Regarding medicinal theory: Sweet-Warm tonifies Qi, Sweet-Cool nourishes Yin. If both Qi and Blood are deficient, tonifying Qi alone allows abundant Yang to generate Yin.
Li Dongyuan stated: Fever during the day and quietness at night indicates Yang Qi flourishing in the Yang divisions. Fever at night and quietness during the day indicates Yang Qi sinking into the Yin, named "Heat entering the Blood Chamber". Fever and irritability both day and night indicate Extreme Yang without Yin; one must urgently drain the Yang and vigorously tonify the Yin.
Wang Bing stated: When a patient has fever but the pulse appears normal, and pressing reveals no pulsation, this is caused by Cold excess repelling Yang, not true Heat. When symptoms and signs indicate Cold, but pressing reveals a pulsating pulse under the fingers, this is Heat excess repelling Yin, not true Cold.
Zhao Yangkui stated: Fever with thirst, desire for cold drinks, and constipation belongs to Excess Heat, which everyone knows. Aversion to cold, fever, curling up holding clothes, cold limbs, and loose stools belong to True Cold, which is also easily known. However, restlessness, mania, dislike of clothing, and desire to sit in mud or water belong to False Heat syndromes. Severe cases involve extreme restlessness, incessant thirst, tongue like thorns, cracked lips, face painted red, body feeling like burning, soles of feet like iron branding, profuse expectoration,急促 breathing, constipation, and scanty urination. The three positions of the pulse are flooding and boundless. At this time, it resembles a Chengqi Syndrome, but if Chengqi Tang enters the mouth, death follows immediately; it resembles a Baihu Syndrome, but if Baihu Tang is swallowed, death follows. Erwan pills are too slow. Urgently use Jiajian Bawei Wan formula (Modified Eight-Ingredient Pill) in large quantities, adding Rougui (Cinnamon Bark), decocted in water to yield several bowls, served cold. Symptoms will recede. The next day, there will likely be aversion to cold and deep pulse, indicating absence of Fire; one must tonify Yang, urgently using Fuzi Bawei Wan (Aconite Eight-Ingredient Pill) decoction to heal. This syndrome and pulse deviate from norms and require non-standard treatment. In cases of postpartum or massive blood loss, sudden injury to Yin Blood causes high fever, also called Yin Deficiency Fever. Using cooling medicines for direct treatment leads to immediate death. As the saying goes, resembling Baihu Syndrome, taking Baihu Tang causes death. One must use Dushen Tang (Single Ginseng Decoction) or Danggui Buxue Tang (Angelica Tonifying Blood Decoction) to generate the formless (Qi), illustrating the wonder of "Yang generating Yin". Someone asked: Qi deficiency and Blood deficiency are both internal injuries; how to distinguish them? Answer: In Yin deficiency, the face must be red, with rootless Fire floating upwards. In Yang syndromes, Fire enters inward, and the face is not red. Those with thirst have dried-up Kidney Water, drawing water to save themselves. Although the mouth is thirsty, the tongue must be slippery; although the pulse is rapid, the Chi position must be powerless. Even if the Chi position is flooding and rapid, pressing reveals no pulsation; this is the key to differentiation. Dai Fu'an said: If the pulse remains rapid after taking cooling medicines, it is Fire Depression, suitable for lifting and tonifying.
Wang Jiezhai stated: Among fevers in the world, several resemble Taiyang disease (Shanghan), but treatments differ greatly. External contraction and internal injury are the major keys. Zhang Zhongjing's discussion on Shanghan and Shangfeng refers to external contraction. Wind-Cold enters from the exterior to the interior, so releasing the exterior to dissipate is indicated; this is the principle of Mahuang Tang (Ephedra Decoction) and Guizhi Tang (Cinnamon Twig Decoction). Because contraction occurs in the cold seasons of Winter and Spring, pungent-hot herbs are used to overcome cold. If the season is not cold, the herbs must change. In warm Spring months, pungent-cool herbs are used; in hot Summer months, sweet-bitter-cold herbs are used. Thus it is said: Shanghan that does not manifest immediately may transform into Wenbing (Warm Disease) in Spring and Rebing (Heat Disease) in Summer. Treatment methods must vary according to the season. There is also a winter-warm disease, called having the qi of another season; though it is winter cold, one contracts warmth. This is improper seasonal qi, with Yang leaking; warming herbs are contraindicated. There is also a seasonal cold epidemic occurring in warm times, where cold becomes the disease. This is also improper seasonal qi, with Yin reversing; cooling herbs are contraindicated. There is also a pandemic warm-febrile disease, occurring mostly in early Spring and Summer, affecting entire households similarly. This is a pestilential qi of Heaven and Earth; treatment should follow the season and consult the Six Qi transformations, using Liu Hejian's pungent-cool, sweet-bitter-cold herbs to clear heat and detoxify. All above syndromes are external contractions of Heaven and Earth's pathogenic qi.
However, dietary irregularity and fatigue injure Yuan Qi internally, causing True Yang to sink and generating internal deficiency heat. Thus Li Dongyuan proposed the theory of Buzhong Yiqi, using Renshen and Huangqi (Astragali Radix) and other sweet-warm herbs to tonify Qi and lift the sunken Qi. This uses Qi-tonifying herbs to supplement insufficient Qi.
Furthermore, mental overwork and sexual indulgence injure True Yin internally. Once Yin Blood is injured, Yang Qi becomes relatively excessive and transforms into Fire, constituting Yin Deficiency with Fire Hyperactivity and Consumptive Disease. Thus Zhu Danxi proposed the theory of "Yang Excess and Yin Insufficiency," using Siwu Tang (Four Substances Decoction) added with Huangbai (Phellodendri Cortex) and Zhimu (Anemarrhenae Rhizoma) to tonify Yin, causing Fire to descend naturally. This uses Blood-tonifying herbs to supplement insufficient Blood. Tonifying Qi and Nourishing Yin are both internal injury syndromes. One lifts sunken Yang Qi; the other nourishes Yin to descend rising Yang Fire. One ascends, one descends; they are completely different.
There is also Summerheat injury in Summer. Although it is external contraction, it resembles internal injury and differs greatly from Shanghan. Cold injures the Form; Cold Pathogen lodges in the Exterior, an Excess syndrome, so sweating is indicated. Summerheat injures Qi; Original Qi is damaged by hot Qi, a depletion/insufficiency syndrome, so tonification is indicated. This is what Li Dongyuan meant by "Tonifying Qi and Clearing Summerheat."
There is also illness caused by consuming excessive cold items due to seasonal summer heat, injuring the interior; or seeking excessive cool wind, injuring the exterior. This is not Summerheat injuring people, but self-induced illness due to Summerheat. Treatment should use pungent-hot exterior-releasing or pungent-warm Middle-Jiao-regulating herbs, similar to Shanghan treatment methods.
All these syndromes appear similar externally but differ实质上. Treatments are diverse and must not be erroneous. External contraction vs. Internal injury, Cold disease vs. Heat disease, Qi deficiency vs. Blood deficiency are like ice and charcoal. If treatment errs, mild disease becomes severe, and severe disease leads to death. Must one not be cautious?
Zhang Jingyue stated: Yin deficiency with Yang hyperactivity, or simultaneous Yin and Yang deficiency, presenting with alternating chills and fever, stems from True Yin insufficiency and belongs generally to deficiency damage. However, the degree of Yin and Yang must be distinguished. Fever by day and quiet by night indicates Yang pathogen flourishing in Yang divisions, Yang excess. Quiet by day and fever by night indicates Yang pathogen sinking into Yin, Yin insufficiency. Fever and irritability both day and night, with excessive sweating, but not external contraction, though called Extreme Yang, is actually Extreme Yin deficiency. Loose stools or upper vomiting/nausea with tidal fever and night fever indicate Rootless Yuan Qi and Yang deficiency. Generally, Yang Excess requires draining Yang using bitter-cold; Yin Deficiency requires tonifying Yin using sweet-cool. For Yang Deficiency alone, even if there is fever, cooling herbs are strictly contraindicated; many fail to recognize this.
When Cold Pathogen suppresses meridians, causing chills and fever, resembling malaria but not quite, treatment should involve dispersing. However, if pathogen lingers long, it is due to Yuan Qi deficiency where Healthy Qi cannot overcome Pathogen. Thus, treatment must primarily tonify Qi and Blood. If chronic illness leads to great Yuan Qi deficiency with persistent chills and fever, only tonify Yuan Qi without dispersing. Observe Yin and Yang, choose accordingly. If truly Yang deficient, warming tonification is indispensable.
He also stated: Cold arising internally spreads from Zang organs to the exterior, causing shivering, aversion to cold, or cold limbs and spasms. Generally, Heat is mostly Excess, Cold is mostly Deficiency. Thus, treating Cold syndromes requires observing Deficiency and checking Zang organs; this is an unchanging method.