外因之病，风为最多；内因之病，火为最烈。风者天之气，火者人之气也。火之为物，本无形质，不能孤立，必
与一物相为附丽，而始得常存。故方其静也，金中有火，而金不销也；木中有火，而木不焚也；水中有火，而
水不沸也；土中有火，而土不焦也；但见有金、有木、有水、有土，而不见火也。五行各有其用，五行惟火无体，
火之体，即以金木水土之体为之体也。及其发而莫可遏也，销金烁石，焚岗燎原，而炎威乃不可响迩矣。
人身之火，何独不然，方其静也，肺气肃而大肠润，金不销也；肝气平而胆气清，木不焚也；肾气充而膀胱
通，水不沸也；脾气健而胃气和，土不焦也。一经激发，则金销水涸，木毁土焦，而百病丛生矣。其因于风者
为风火；因于湿者为湿火；因于痰者为痰火。阳亢者为实火；劳伤者为虚火；血虚者为燥火；遏抑者为郁
火；酒色受伤者为邪火；疮疡蕴结者为毒火。又有一种无名之火，不归经络，不主病症，暴猝举发，莫能自
制，则气血偏胜所致也。种种火症，或由本经自发，或由他经侵克，或有数经合病，必察其所以致病之由，
方能对病施治，业医者尚慎旃哉！
肺火自本经而发者，缘燥气相逼，清肃之令不能下行，故肺气焦满，微喘而咳，烦渴欲饮，鼻端微红，肌肤
作痒，润燥泻肺汤主之。
润燥泻肺汤（自制）
玉竹（四钱） 蒌皮（三钱） 桑皮（三钱） 沙参（四钱） 麦冬（二钱）
黄芩（一钱） 贝母（二钱） 杏仁（三钱） 苡仁（四钱） 梨汁（半杯冲服）
此方用玉竹、沙参、麦冬、贝母、蒌皮、杏仁，同于清金保肺汤。而梨直用汁，因火之烈尤甚于燥。金本畏火，
东垣治肺热如火，烦燥引饮而昼甚者，用一味黄芩汤，以泻肺金气分之火。先生因之，再加栝蒌、桑皮、
苡仁，而肺家之实火可以下行而出矣。祖怡注。
Diseases caused by external factors are most frequently due to Wind; diseases caused by internal factors are most severe when due to Fire. Wind is the Qi of Heaven (nature), while Fire is the Qi of Man (humanity). As a substance, Fire has no inherent form or quality and cannot exist independently; it must adhere to another entity to persist. Therefore, in its static state, Metal contains Fire yet does not melt; Wood contains Fire yet does not burn; Water contains Fire yet does not boil; Earth contains Fire yet does not scorch. One sees only Metal, Wood, Water, and Earth, but not Fire itself. The Five Elements each have their functions, but among them, only Fire lacks an independent body; the body of Fire is constituted by the bodies of Metal, Wood, Water, and Earth. However, when it erupts uncontrollably, it can melt metal and shatter stones, burn hills and plains, making its blazing intensity unbearable to approach.
Is the Fire within the human body any different? In its static state, Lung Qi descends properly, keeping the Large Intestine moist, so Metal does not melt; Liver Qi is peaceful, keeping Gallbladder Qi clear, so Wood does not burn; Kidney Qi is abundant, keeping the Bladder unobstructed, so Water does not boil; Spleen Qi is robust, keeping Stomach Qi harmonious, so Earth does not scorch. Once stimulated, however, Metal melts, Water dries up, Wood is destroyed, and Earth scorches, leading to the emergence of myriad diseases. Those arising from Wind are called Wind-Fire; those from Dampness are called Damp-Fire; those from Phlegm are called Phlegm-Fire. Excessive Yang constitutes Excess Fire; injury from overwork constitutes Deficiency Fire; Blood deficiency constitutes Dryness Fire; constrained Qi constitutes Stagnant Fire; injury from alcohol and sexual excess constitutes Pathogenic Fire; accumulation in sores and ulcers constitutes Toxic Fire. There is also a type of nameless Fire that does not belong to any meridian nor govern specific symptoms; it erupts suddenly and cannot be controlled by oneself, resulting from an imbalance where Qi and Blood become excessive in certain areas. Various Fire syndromes may originate spontaneously from the affected meridian, invade and overcome other meridians, or involve multiple meridians simultaneously. One must examine the cause of the disease to treat it appropriately. Practitioners must exercise great caution!
When Lung Fire originates spontaneously from the Lung Meridian, it is due to Dryness Qi forcing its way in, preventing the descending function of Clearing and Purifying from going downward. Consequently, Lung Qi becomes scorched and distended, accompanied by slight wheezing and coughing, irritability, thirst with desire to drink, slight redness at the nasal tip, and itching of the skin. Run Zao Xie Fei Tang (Moistening-Drying and Draining-Lung Decoction) is the primary prescription.
Run Zao Xie Fei Tang (Self-made Formula)
* *Asparagi Radix* (Yuzhu, 4 qian)
* *Trichosanthis Pericarpium* (Gualou Pi, 3 qian)
* *Morus Cortex* (Sang Bai Pi, 3 qian)
* *Glehniae Radix* (Shashen, 4 qian)
* *Ophiopogonis Radix* (Maidong, 2 qian)
* *Scutellariae Radix* (Huangqin, 1 qian)
* *Fritillariae Bulbus* (Beimu, 2 qian)
* *Armeniacae Semen Amarum* (Xingren, 3 qian)
* *Coicis Semen* (Yiyiren, 4 qian)
* *Pyrus Juice* (Lizhi, half cup, taken mixed in)
This formula uses Yuzhu, Shashen, Maidong, Beimu, Gualou Pi, and Xingren, which are identical to Qing Jin Bao Fei Tang (Clear-Metal and Protect-Lung Decoction). However, using Pear juice directly is because the intensity of Fire exceeds that of Dryness. Metal naturally fears Fire. Li Dongyuan treated cases of Lung Heat like fire, with irritability, thirst for drinking, and worsening during the day, using a single-herb Huangqin Tang to drain the Fire in the Qi aspect of Lung Metal. The author followed this method, adding Gualou, Sang Bai Pi, and Yiyiren, so that Excess Fire in the Lungs could descend and exit. Annotated by Zu Yi.