张景岳曰∶汗出一症，有自汗，有盗汗。自汗属阳虚，治宜实表补阳；盗汗属阴虚，阴虚阳必凑之，
故阳蒸阴分，治
宜清火补阴。然自汗中亦有阴虚，盗汗中亦多阳虚。如遇烦劳火热之类，最多自汗，故饮食之火起于胃，
酒色之火起于肾，能令人自汗，此非阳盛阴衰而何？且人之寤寐，总由卫气之出入，卫气者，阳气也，
人寐时卫入于阴，非阳虚于表而何？欲辨阴阳，当察其有火无火。火盛而汗出者，以火烁阴，阴虚也；无火
汗出者，表气不固，阳虚也。知斯二者，无余义矣。
一、汗由血液，本乎阴也。然汗发于阴而出于阳，此其根本，则由阳中之营气；而其启闭，则由阴中之
卫气。故凡欲疏汗而不知营卫之盛衰，欲禁汗而不知阴阳之橐龠，吾知其必败矣。
一、汗有阴阳。人但知热能致汗，而不知寒亦能致汗。所谓寒者，非曰外寒，以阳气内虚，则寒生于中，
而阴中无阳，阴无所主，故汗随气泄。凡大惊恐惧，皆令汗出，是皆阳气顿消，真元失守之兆。如病后、产
后、大吐大泄失血后，必多汗出，岂非气去而然乎？经曰∶阴胜则自寒汗出，身常清，数栗而寒，寒则厥，
厥则腹满，死。仲景曰∶极寒反汗出，身必冷如冰。是皆阴汗之谓。治此当察气虚之微甚，微虚者略扶正气，
汗自收；甚虚者，非速救元气不可，即姜、桂、附之属，必所当用。
又湿气乘脾，亦能作汗。症见身重困倦，脉见缓大，声音如从瓮中出者，多属湿症。但湿热甚者，去火
而湿自清。寒湿胜者，助火而湿自退；健脾土之气，则湿去而汗自收。丹溪曰∶心之所藏，在内者为血，发
外者为汗。汗为心液，故自汗之症，未有不由心肾俱虚而得者。故阴虚阳必凑，发热而自汗；阳虚阴必乘，
发厥而自汗。皆阴阳偏胜所致也。
李士材曰∶汗为心之液，而肾主五液，故汗症未有不由
心肾虚而得者。心阳虚，不能卫外而为固，则外伤而自汗；肾阴虚，不能内营而退藏，则内伤而盗汗。
及夫肺虚、脾虚，皆令汗出。治法∶肺虚者，固其皮毛，黄 六一汤、玉屏风散；脾虚者，壮其中气，
补中益气汤、四君子汤；心虚者，益其血脉，当归六黄汤；肝虚者，禁其疏泄，白芍、枣仁、乌梅；肾虚者，
助其封藏，五味、山萸、龙骨、牡蛎、远志、五倍、首乌。五脏之内，更有宜温、宜清、宜润、宜燥，无胶
一定之法，以应无穷，可耳。
张三锡曰∶阳衰则卫虚，所虚之卫，行阴当瞑目之时，则更无气以固其表，故腠理开、津液泄而为汗。
迨寐则目张，其行阴之气，复散于表，则汗止矣。夫如是者，谓之盗汗，即《内经》之寝汗也。然自汗、盗
汗，虽分阴虚、阳虚，细而察之，悉属于卫。且卫气者，实由谷气之所化，肺脏之所布，天真之阳必得是而
后充大，无是则衰微。故《素问》曰∶阳气者，如苍天之气，顺之则阳气固。又曰∶阳因而上，卫外者也。
又曰∶阳者卫外而为固也。又曰∶卫气者，所以肥腠理，温分肉，而司开阖者也。学人不可不知。
Zhang Jingyue stated: The symptom of sweating is divided into spontaneous sweating (Zihan) and night sweats (Daohan). Spontaneous sweating belongs to Yang deficiency, and the treatment should focus on consolidating the exterior and tonifying Yang. Night sweats belong to Yin deficiency; when Yin is deficient, Yang tends to encroach upon it, causing Yang to steam the Yin compartment, so the treatment should focus on clearing fire and nourishing Yin. However, there are cases of Yin deficiency within spontaneous sweating, and many cases of Yang deficiency within night sweats. For instance, when encountering factors such as mental fatigue or heat-fire, spontaneous sweating is most common. Thus, fire arising from improper diet originates in the Stomach, and fire arising from sexual excess originates in the Kidney; both can cause spontaneous sweating. Is this not a case of Excess Yang and Deficient Yin? Furthermore, human wakefulness and sleep depend entirely on the movement of Wei Qi (Defensive Qi). Wei Qi is Yang Qi. When a person sleeps, Wei Qi enters the Yin compartments; is this not a sign of deficiency of Yang at the exterior? To distinguish between Yin and Yang, one must observe whether there is Fire present. If sweating occurs with abundant Fire, it is because Fire scorches the Yin, indicating Yin deficiency. If sweating occurs without Fire, it is due to insecurity of the Exterior Qi, indicating Yang deficiency. Understanding these two aspects leaves no further ambiguity.
First, sweat is derived from blood and fundamentally belongs to Yin. However, sweat originates from Yin but exits through Yang. Its root lies in the Ying Qi (Nutritive Qi) within Yang, while its opening and closing are controlled by the Wei Qi (Defensive Qi) within Yin. Therefore, anyone who seeks to stop sweating without understanding the abundance or decline of Ying and Wei, or who seeks to induce sweating without understanding the pivot of Yin and Yang, I predict will certainly fail.
Second, sweating has Yin and Yang characteristics. People only know that Heat causes sweating, but do not know that Cold can also cause sweating. The "Cold" referred to here does not mean external Cold, but rather internal Cold generated due to deficiency of Yang Qi inside. When there is no Yang within the Yin, the Yin lacks mastery, and thus sweat leaks out following the Qi. Any sudden fright or fear causes sweating, which is a sign of sudden consumption of Yang Qi and loss of True Yuan (Primordial Qi). After illness, postpartum, or after severe vomiting, diarrhea, or blood loss, excessive sweating is inevitable. Is this not due to the departure of Qi? The *Classic of Difficult Issues* (*Nan Jing*) states: "When Yin prevails, there is cold sweating, the body feels constantly clear/cold, frequent shivering and chills occur. Chills lead to cold limbs (Jue), and cold limbs lead to abdominal fullness, which is a death sign." Zhang Zhongjing said: "Extreme cold leads to sweating, and the body becomes cold as ice." These all refer to Yin sweating. Treatment for this condition requires assessing the degree of Qi deficiency. In mild deficiency, slightly supporting the Righteous Qi will naturally stop the sweating. In severe deficiency, it is imperative to rapidly rescue the Yuan Qi; herbs such as Sheng Jiang (Raw Ginger), Rou Gui (Cinnamon Bark), and Fu Zi (Aconite Root) must be used.
Additionally, Dampness invading the Spleen can also cause sweating. Symptoms include heaviness and lassitude of the body, a slow and large pulse, and a voice that sounds as if it comes from an urn. This mostly indicates a Dampness syndrome. However, if Damp-Heat is severe, removing the Fire will naturally clear the Dampness. If Cold-Dampness prevails, assisting the Fire (Yang) will naturally recede the Dampness; strengthening the Qi of the Spleen Earth will remove the Dampness and naturally stop the sweating. Zhu Danxi said: What the Heart stores internally is Blood, and what emerges externally is Sweat. Sweat is the fluid of the Heart. Therefore, spontaneous sweating arises invariably from deficiency of both the Heart and the Kidney. Thus, Yin deficiency leads to Yang encroachment, causing fever and spontaneous sweating; Yang deficiency leads to Yin invasion, causing cold limbs and spontaneous sweating. All are caused by the predominance of either Yin or Yang.
Li Shicai said: Sweat is the fluid of the Heart, and the Kidney governs the five fluids. Therefore, sweating disorders arise invariably from deficiency of the Heart and Kidney. Heart Yang deficiency fails to protect the exterior and maintain consolidation, leading to external injury and spontaneous sweating. Kidney Yin deficiency fails to nourish internally and store, leading to internal injury and night sweats. Lung deficiency and Spleen deficiency also cause sweating. Treatment methods: For Lung deficiency, consolidate the skin and hair using Huang Qi Liu Yi Tang (Honeydew Melon Seed and Astragalus Decoction) or Yu Ping Feng San (Jade Windscreen Powder). For Spleen deficiency, strengthen the Middle Qi using Bu Zhong Yi Qi Tang (Tonify the Middle and Augment the Qi Decoction) or Si Jun Zi Tang (Four Gentlemen Decoction). For Heart deficiency, benefit the blood vessels using Dang Gui Liu Huang Tang (Angelica Sinensis and Six Yellow Herbs Decoction). For Liver deficiency, restrict excessive dispersion using Bai Shao (White Peony Root), Zao Ren (Ziziphus Seed), and Wu Mei (Mume Fruit). For Kidney deficiency, assist sealing and storing using Wu Wei Zi (Schisandra Berry), Shan Yu Rou (Cornus Fruit), Long Gu (Fossilized Bones), Mu Li (Oyster Shell), Yuan Zhi (Polygala Root), Wu Bei Zi (Gallnut), and Shou Wu (Polygonum Multiflorum). Within the five Zang organs, treatments may require warming, clearing, moistening, or drying. There is no rigid, fixed method to accommodate infinite variations.
Zhang Sanxi said: When Yang declines, Wei Qi becomes deficient. During the time of sleep when deficient Wei Qi travels through the Yin, there is insufficient Qi to consolidate the exterior, causing the pores to open and body fluids to leak out as sweat. Upon waking, when the eyes open, the Qi that traveled through Yin disperses back to the exterior, and sweating stops. Such cases are called night sweats, which correspond to "sweat during sleep" (Qin Han) in the *Inner Canon*. Although spontaneous sweating and night sweats are distinguished as Yin deficiency and Yang deficiency respectively, a detailed examination reveals they all pertain to Wei Qi. Moreover, Wei Qi is indeed transformed from Grain Qi and distributed by the Lung organ. Innate Yang Qi must rely on Wei Qi to become robust; without it, Yang Qi becomes weak. Therefore, the *Su Wen* (Basic Questions) states: "Yang Qi is like the Qi of the vast sky; complying with it makes Yang Qi firm." It also states: "Yang Qi moves upward and protects the exterior." And again: "Yang Qi protects the exterior and maintains consolidation." And once more: "Wei Qi is what fleshes out the interstices, warms the muscles, and controls opening and closing." Students of medicine must not ignore this.