气取诸阳，血取诸阴。人生之初，具此阴阳，则亦具此气血。气血者，其人生之根本乎
。血
何以为营？营行脉中，滋荣之义也。气何以为卫？卫行脉外，护卫之义也。然则营与卫，岂独
无所自来哉？曰∶人受谷于胃，胃为水谷之海，灌溉经络，长养百骸，五脏六腑，皆取其气
故清者为营，浊者为卫，营卫之气，周流不息，一日一夜，脉行五十度，平旦以复会于气口
，所谓阴阳相贯，如环无端，则是二气恒相随而不相离也。夫惟血营气卫，常相流通，则人
何病之有？一有窒碍，百病由此生矣。故气之作养，发而为喜怒忧悲惊恐寒热思劳，聚而为
积痞 瘕 癖，上为头旋，中为五膈，下为脐间动气，或喘促，或咳噫，聚则中满，逆则足
寒。凡此者，皆气使之然也。血之为患，其妄行则为吐衄，其衰涸则为虚劳，蓄之在上其人
妄，蓄之在下其人狂，逢寒则筋不营而挛急，挟热则内瘀而发黄，在小便则为淋痛，在大便
则为肠风，在妇人月事进退漏下崩中病尤不一，凡此者，皆血使之然也。夫血譬之水也，气
譬之风也，风行水上，即气血之义也。盖气血之帅也。气行则血行，气止则血止，气温则血
活。气寒则血凝，气有一息之不运，则血有一息之不行，病出于血，调其气犹可以导之。病
原于气，区区调血何与焉？人之一身，调气为主，是亦先阳后阴之义也。若夫血有败瘀泥滞
乎诸经，则气之道，未免有所壅遏，又当审所先而决去之。经所谓先去其血，而后调之，又
不可不通其变矣！然则调气之剂，以之调血则两得。调血之剂，以之调气则乖张，如香附、
木香之类，治气可也，治血亦可也。若以归、地辈论之，则其性缠绵，于胃气有亏矣，用药
者审之。
气归属于阳，血归属于阴。人生命之初，具备阴阳，也就具备了气血。气血，大概是人生的根本吧？
血为什么称为“营”？营行于脉管之中，具有滋养荣润的意义。气为什么称为“卫”？卫行于脉管之外，具有护卫机体的意义。既然这样，那么营和卫，难道没有来源吗？回答说：人从胃中摄取水谷精微，胃是水谷汇聚的海，灌溉经络，长久养育骨骼形体，五脏六腑都依赖它的气化作用。所以清轻的部分成为营，重浊的部分成为卫，营卫之气，周流不息，一天一夜，在脉道中运行五十周次，清晨时分重新会合于寸口脉，这就是所说的阴阳相互贯通，像圆环一样没有端点，这两股气恒常相随而不分离。正因为血营气卫，经常保持流通，人怎么会生病呢？一旦有阻滞阻碍，各种疾病就由此产生了。
所以气的失常，发作出来表现为喜怒忧悲惊恐寒热思虑劳累的异常情绪或状态，积聚起来形成积块、痞块、瘕聚、癖积，向上导致头晕目眩，中部导致五膈（泛指胸膈部位的阻塞性疾病），下部导致脐间动气，或者气喘急促，或者咳嗽嗳气，气聚则腹部胀满，气逆则足部寒冷。所有这些情况，都是气造成的。血的致病，它的妄行则导致吐血、衄血，它的衰败枯竭则导致虚劳病，蓄积在上部使人精神狂妄，蓄积在下部使人发狂，遇到寒邪则筋脉失养而痉挛拘急，夹杂热邪则内部瘀滞而发黄，在小便方面表现为淋证疼痛，在大便方面表现为肠风（便血），在妇女月经方面表现为月经进退不调、漏下、崩中等，病情尤其多样。所有这些情况，都是血造成的。
血好比是水，气好比是风，风吹在水面上，就是气血关系的含义。气是血的统帅。气行则血行，气停则血停，气温则血活。气寒则血凝，气有一息不运行，则血也有一息不流动。疾病出于血分，调理气机还可以引导治疗。疾病原发于气分，仅仅调理血分又有什么用呢？人的一身，以调气为主，这也是先阳后阴的道理。如果血液有败坏的瘀血泥滞在各条经脉，那么气的通道，难免有所壅塞遏制，这时应当审察先后顺序而决断去除它。医经所谓先去其瘀血，然后调理气血，这也不可不通晓其变化啊！
然而，调气的药剂，用来调血则两全其美。调血的药剂，用来调气则格格不入。比如香附、木香这类药物，治疗气病可以，治疗血病也可以。至于当归、地黄这一类药物，它们的性质缠绵滋腻，会亏损胃气，用药的人要审慎对待。
Qi is derived from Yang, and Blood is derived from Yin. At the beginning of human life, possessing Yin and Yang means also possessing Qi and Blood. Qi and Blood are perhaps the root of human life?
Why is Blood called "Ying" (Nutritive Qi)? Ying circulates within the vessels, signifying the meaning of nourishing and flourishing. Why is Qi called "Wei" (Defensive Qi)? Wei circulates outside the vessels, signifying the meaning of guarding and protecting. If so, do Ying and Wei not have a source? It is said: Humans receive grain from the Stomach; the Stomach is the sea of water and grain, irrigating the meridians and long-term nourishing the bones and body. The Zang and Fu organs all derive their Qi from it. Therefore, the clear part becomes Ying, and the turbid part becomes Wei. The Qi of Ying and Wei circulates ceaselessly. In one day and one night, it travels fifty cycles through the vessels, reconverging at the Qi Kou (Cunkou pulse) at dawn. This is what is meant by Yin and Yang interconnecting like a ring without end; these two Qi constantly accompany each other and do not separate. Because Blood-Ying and Qi-Wei flow continuously, how can a person fall ill? Once there is obstruction, all diseases arise from this.
Thus, when Qi malfunctions, it manifests as abnormal emotions or states such as joy, anger, sorrow, grief, fear, fright, cold, heat, and overthinking or fatigue. When it accumulates, it forms masses,痞 (Pi - stuffiness), Jia (soft masses), and Pi (hard masses). Ascending, it causes dizziness; in the middle, it causes the Five Ge (obstructions in the chest/diaphragm); descending, it causes moving Qi around the umbilicus. It may cause panting or belching; accumulation leads to abdominal fullness, and rebellion leads to cold feet. All these conditions are caused by Qi.
When Blood causes pathology, its reckless flowing leads to hematemesis or epistaxis; its depletion leads to deficiency consumptive disease. Accumulation in the upper body causes madness; accumulation in the lower body causes mania. Encountering Cold causes the sinews to lack nourishment and become spasmodic; accompanying Heat causes internal stasis leading to jaundice. In urination, it presents as painful dysuria; in defecation, it presents as intestinal wind (blood in stool). In women, it presents as irregular menstruation, spotting, or metrorrhagia, with particularly diverse pathologies. All these conditions are caused by Blood.
Blood is likened to water, and Qi is likened to wind. Wind blowing on water illustrates the relationship between Qi and Blood. Qi is the commander of Blood. Where Qi moves, Blood moves; where Qi stops, Blood stops. Where Qi is warm, Blood is active. Where Qi is cold, Blood coagulates. If Qi fails to move for even an instant, Blood fails to flow for that same instant. If disease originates in Blood, regulating Qi can still guide the treatment. If disease originates in Qi, what use is merely regulating Blood? In the entire body, regulating Qi is primary, which aligns with the principle of prioritizing Yang before Yin. However, if blood has degenerated into stasis and stagnation within the meridians, the pathways of Qi will inevitably be blocked. In such cases, one must assess the priority and remove the obstruction. As the classics state, one should first remove the blood stasis and then regulate, a variation that must be understood.
Therefore, formulas for regulating Qi can effectively regulate Blood as well. Conversely, formulas for regulating Blood are unsuitable for regulating Qi. For example, Xiangfu (Cyperi Rhizoma) and Muxiang (Aucklandiae Radix) can treat Qi disorders and also Blood disorders. Regarding Guizhi Tang (Cinnamon Twig Decoction) members like Danggui (Angelicae Sinensis Radix) and Dihu (Rehmanniae Radix), their nature is cloying and sticky, which may impair Stomach Qi. Practitioners must exercise caution.