前贤谓∶气能生血，血不能生气，固矣。然血虽不能生气，气必赖血以藏之。所谓气生
血者
，即西医所谓化学中事也。人身有一种气，其性情功力能鼓动人身之血，由一丝一缕，化至
十百千万，气之力止，而后血之数止焉。常见人之少气者，及因病伤气者，面色络色必淡，
未尝有失血之症也，以其气力已怯，不能鼓化血汁耳!此一种气，即荣气也，发源于心，取
资于脾胃，故曰心生血，脾统血。非心、脾之体，能生血、统血也，以其脏气之化力能如此
也。
所谓血藏气者，气之性情 悍滑疾，行而不止，散而不聚者也。若无以藏之，不竟行而
竟散
乎?惟血之质为气所恋，因以血为气之室，而相裹结不散矣。故人之暴脱血者，必元气浮动
而暴喘；久脱血者，必阳气浮越而发热；病后血少者，时时欲喘欲呕，或稍劳动即兀兀欲呕
，或身常发热。此皆血不足以维其气，以致气不能安其宅也。此其权主乎肝肾。肝之味酸，
肾之味咸，酸咸之性，皆属于敛。血之所以能维气者，以其中有肝肾之敛性在也。故曰肝藏
血，非肝之体能藏血也，以其性之敛故也。精由血化，藏气之力更强，故又必肾能纳气，而
气始常定也。明乎此，则知气血相资之理，而所以治之者，思过半矣。血虚者，当益其气；
气暴者，尤当滋其血也。
夫生血之气，荣气也。荣盛即血盛，荣衰即血衰，相依为命，不可离者也。藏于血之气
，卫
气也，宗气也。气亢则血耗，血少则气散，相辅而行，不可偏者也。荣气主湿，卫气主热，
宗气主动。荣气不能自动，必借宗气之力以运之。 卫气虽自有动力，而宗气若衰，热亦内
陷。故人有五心 热，骨蒸烦热者，宗气之力不能运热于外也；水停心下，困倦濡泄者，宗
气之力不能运湿于外也。
前代贤人曾说：气能生血，但血不能生发气，这确实是正确的。然而，血虽然不能生发气，但气必须依赖血来涵养它。所谓“气生血”，即相当于西医所说的化学变化过程。人体有一种气，其性质和功能能够鼓动人体的血液，从一丝一缕，化生为十、百、千、万之多，当这种气的力量停止时，血液的化生也就停止了。常见那些元气不足的人，以及因病损伤元气的人，面色和络脉颜色必然淡白，并没有失血的病症，这是因为他们的元气力量已经虚弱，不能鼓动化生血液的缘故！这种气，就是营气（运行于脉中、具有营养作用的气），发源于心，取资于脾胃，所以说“心生血，脾统血”。并不是心和脾的实体器官本身能生血、统血，而是因为脏腑之气的化生功能能达到这样的效果。
所谓“血藏气”，是指气的性质刚悍、滑利、疾速，运行不停止，容易散漫而不凝聚。如果没有东西来涵养它，难道不是让它完全运行而最终消散吗？只有血的质地被气所眷恋，因此以血作为气的居所，从而相互包裹结合而不散乱。所以，那些突然大量失血的人，必定会出现元气浮动而突发喘息；长期失血的人，必定出现阳气浮越而发热；病后血少的人，时常想要喘息或呕吐，或者稍微劳动就感到头晕恶心，或者身体经常发热。这些都是因为血不足以维系气，导致气无法安守其宅邸。这种情况的主导权在于肝和肾。肝的味道酸，肾的味道咸，酸和咸的性质，都属于收敛。血之所以能维系气，是因为其中含有肝肾的收敛特性。所以说“肝藏血”，并非肝脏的实体功能能藏血，而是因为肝性主收敛的缘故。精由血化生，涵养气的力量更强，所以又必须依靠肾能纳气，气才能长久安定。明白了这些道理，就知道气血相互资助的原理，那么治疗的方法也就掌握了一大半了。血虚的人，应当补益其气；气机亢逆的人，尤其应当滋养其血。
那生血的气，是营气。营气旺盛则血盛，营气衰弱则血衰，二者相依为命，不可分离。藏在血中的气，是卫气（行于脉外、具有防御作用的气）和宗气（积于胸中、推动呼吸和心血运行的气）。气亢盛则耗伤血，血少则气散，二者相辅相成，不可偏废。营气主湿，卫气主热，宗气主动。营气不能自行运动，必须借助宗气的力量来运化。卫气虽然自有动力，但如果宗气衰弱，热邪也会内陷。所以，有人出现五心烦热、骨蒸烦热的症状，是因为宗气的力量不能将热邪运出体外；水饮停聚在心下，导致困倦、大便溏泄的症状，是因为宗气的力量不能将湿气运出体外。
The sages of old stated: "Qi generates Blood, but Blood does not generate Qi," which is indeed correct. However, although Blood cannot generate Qi, Qi must rely on Blood to nourish and retain it. The so-called "Qi generates Blood" corresponds to what Western medicine describes as chemical processes. There exists a type of Qi in the human body whose nature and function can stimulate the Blood, transforming it from minute strands into vast quantities (ten, hundred, thousand, ten thousand). When the power of this Qi ceases, the generation of Blood also stops. It is commonly observed that individuals with deficient Qi or those whose Qi has been damaged by illness invariably present with pale complexion and faint collateral coloration, without symptoms of blood loss. This is because their Qi strength is weak and unable to stimulate the transformation of blood fluid. This specific Qi is Ying Qi (Nutritive Qi), which originates from the Heart and derives its resources from the Spleen and Stomach; hence it is said that "the Heart generates Blood, and the Spleen controls Blood." It is not that the physical organs of the Heart and Spleen themselves generate or control Blood, but rather that the transformative power of the Zang-Fu Qi achieves this effect.
Regarding "Blood retains Qi," the nature of Qi is fierce, slippery, and rapid; it moves ceaselessly and tends to scatter rather than gather. Without something to retain it, would it not simply move until it dissipates? Only when the substance of Blood is cherished by Qi does Blood serve as the residence for Qi, causing them to wrap around each other and remain united without scattering. Therefore, in cases of sudden massive blood loss, Yuan Qi (Original Qi) inevitably becomes unstable, leading to sudden panting; in cases of chronic blood loss, Yang Qi floats upward, resulting in fever; after an illness, when Blood is scanty, one may frequently feel like panting or vomiting, or experience dizziness and nausea upon slight exertion, or have a persistent low-grade fever. These are all due to Blood being insufficient to sustain Qi, causing Qi to fail in residing securely in its dwelling. The governing authority over this lies with the Liver and Kidney. The flavor of the Liver is sour, and the flavor of the Kidney is salty; both sour and salty properties belong to astringency. The reason Blood can sustain Qi is that it contains the astringent nature of the Liver and Kidney. Thus, it is said that "the Liver stores Blood," not because the physical capacity of the Liver stores Blood, but because its nature is astringent. Essence is transformed from Blood, possessing a stronger power to retain Qi; therefore, it is necessary for the Kidney to grasp Qi for Qi to remain stable long-term. Understanding this principle reveals the mutual assistance between Qi and Blood, meaning that half of the treatment strategy is already understood. For Blood deficiency, one should tonify Qi; for hyperactive Qi, one should especially nourish Blood.
The Qi that generates Blood is Ying Qi (Nutritive Qi). When Ying Qi is abundant, Blood is abundant; when Ying Qi is deficient, Blood is deficient. They depend on each other for life and cannot be separated. The Qi stored within Blood is Wei Qi (Defensive Qi) and Zong Qi (Gathering Qi). Hyperactive Qi consumes Blood, while scanty Blood causes Qi to scatter; they assist each other in movement and neither should be neglected. Ying Qi governs dampness, Wei Qi governs heat, and Zong Qi governs movement. Ying Qi cannot move on its own and must borrow the power of Zong Qi to circulate. Although Wei Qi has its own driving force, if Zong Qi is deficient, heat will sink inward. Consequently, individuals experiencing five-palm heat and bone-steaming fever do so because the power of Zong Qi fails to transport heat outward; water retention below the heart, leading to fatigue and loose stools, occurs because the power of Zong Qi fails to transport dampness outward.