五脏六腑，合手厥阴心包，则六脏六腑，是为十二经脉，其中并无命门之脏腑。前人妄以三焦属命门，谬
矣！考之《铜人图》，有命门穴，在脊十四椎肾俞间。《灵枢·根结论》有云∶根于至阴，结于命门。
命者，目也。由此说推之，则目之中央，是为命门，乃足太阳膀胱经脉之所结也；肾俞中央，是为命门穴，
乃足少阴肾脏之所通也。肾为水脏，膀胱为水腑，而命门则通于水脏水腑之经脉焉。
人之一身，皆气血之所循行。气非血不和，血非气不运，故曰气主煦之，血主濡之。气与血无处不有，今
举其概。肺主气，乃周身毛皮之大气，如天之无不覆也。经云∶宗气上出于肺，以司呼吸，一呼一吸，内通于
脏，故曰呼出心与肺，吸入肝与肾。又三焦出气，以温肌肉，膀胱津液随气化出于皮毛，故曰三焦膀胱者，腠
理毫毛其应。又六脏六腑为十二经脉，荣气行于脉中，卫气行于脉外。由此观之，则五脏六腑，十二经脉，上
下内外，游行环绕，无非一气周流，而健行不息，此人之所以生也。然气为主，血为辅，气为重，血为轻，
故血有不足，可以渐生，若气不立，即死矣。夫人周身毛窍，乃大气之环绕于外，而毛窍之内则有孙络，孙
络之内则有横络，横络之内则有经焉。络与经，皆有血也。孙络、横络之血，起于包中之血海，乃冲脉、任脉
所主，其血则热肉充肤，澹渗皮毛。皮毛而外，肺气主之；皮毛之内，肝血主之。盖冲任之血，肝所主也。
其经脉之血，则手厥阴心包主之，乃中焦取汁奉心化赤之血也。血海之血，行于络脉，男子络唇口而生髭须，
女子月事以时下，皆此血也。心包之血，行于经隧，内养其筋，外荣于脉，皆奉心化赤之血也。血海之血，出
多不死；心包之血，出多便死。是又络脉之血为轻，而经脉之血为重也。经云∶阳络伤，则吐血；阴络伤，则
便血。此血海之血也。一息不运，则机针穷，一丝不续，则霄壤判。此经脉之血也。血、气二者，乃医学之大
纲，学人不可不察也！
The five zang organs and six fu organs, combined with the Pericardium Meridian of Hand-Jueyin (Pericardium), constitute the six zang and six fu organs, which form the twelve meridians. There is no zang or fu organ named "Mingmen" (Gate of Life) among them. The predecessors erroneously attributed the Sanjiao (Triple Burner) to Mingmen; this is a fallacy! Consulting the *Tongren Tu* (Illustrated Manual of Acupoints on the Bronze Man), there is an acupoint named Mingmen, located between the Shenshu (Kidney-Shu) points at the level of the fourteenth thoracic vertebra. The *Ling Shu: Gen Jie* chapter states: "Rooted in Zhiyin, knotted at Mingmen." Here, "Ming" refers to the eyes. Inferring from this statement, the center of the eyes is called "Mingmen," which is where the Foot-Taiyang Bladder Meridian knots; while the Mingmen acupoint at the center of the fourteenth thoracic vertebra is where the Foot-Shaoyin Kidney Meridian connects. The Kidney is the Water Zang, and the Bladder is the Water Fu, whereas Mingmen connects to the meridians of these Water Zang and Water Fu organs.
The entire human body is the pathway for the circulation of Qi and Blood. Qi cannot harmonize without Blood, and Blood cannot circulate without Qi. Therefore, it is said that Qi primarily provides warmth, and Blood primarily provides nourishment. Qi and Blood are present everywhere; here we briefly outline their general functions. The Lung governs Qi, which is the great Qi enveloping the skin and hair of the whole body, much like Heaven covers all things. The classics state: "Zong Qi (Gathering Qi) emerges from the Lung to govern respiration. With each exhalation and inhalation, it internally connects with the viscera." Thus, exhalation is governed by the Heart and Lung, while inhalation is governed by the Liver and Kidney. Furthermore, Qi emanates from the Sanjiao to warm the muscles, and the fluids of the Bladder exit through the skin via Qi transformation. Hence, it is said that the Sanjiao and Bladder correspond to the interstices (Cou Li) and fine hairs. Additionally, the six zang and six fu organs form the twelve meridians; Ying Qi (Nutritive Qi) circulates within the vessels, while Wei Qi (Defensive Qi) circulates outside the vessels. From this perspective, the five zang and six fu organs, along with the twelve meridians, circulate and surround up, down, inside, and outside. This is nothing but the continuous flow of a single Qi, moving vigorously without cease, which is why humans live. However, Qi is primary and Blood is secondary; Qi is heavy and Blood is light. Therefore, if Blood is deficient, it can be gradually regenerated; but if Qi fails to stand firm, death ensues. The pores of the human body are where the great Qi surrounds externally, while within the pores lie Sun Luo (Branch Collaterals); within the Sun Luo are Heng Luo (Transverse Collaterals); and within the Heng Luo are the Jing Mai (Main Vessels). Both collaterals and main vessels contain Blood. The Blood in the Sun Luo and Heng Luo originates from the Sea of Blood in the Danzhong (Pericardium), governed by the Chong Mai (Penetrating Vessel) and Ren Mai (Conception Vessel). This blood warms the flesh, fills the skin, and permeates the hair and skin. Outside the skin, it is governed by Lung Qi; inside the skin, it is governed by Liver Blood. Since the blood of the Chong and Ren vessels is governed by the Liver. As for the blood in the main vessels, it is governed by the Pericardium Meridian of Hand-Jueyin, which is the blood transformed into red by the Heart from the essence extracted from the Middle Jiao. The blood of the Sea of Blood circulates in the collaterals; in men, it causes beard growth on the lips and mouth, and in women, it enables regular menstruation. This is all such blood. The blood of the Pericardium circulates in the vessel tunnels, nourishing the sinews internally and flourishing in the vessels externally; this is also the blood transformed into red by the Heart. If the blood of the Sea of Blood is lost excessively, one does not die; but if the blood of the Pericardium is lost excessively, one dies. This further indicates that the blood of the collaterals is lighter, while the blood of the main vessels is heavier. The classics state: "If Yang Luo is injured, hematemesis occurs; if Yin Luo is injured, hematochezia occurs." This refers to the blood of the Sea of Blood. If breath ceases to move for even a moment, the mechanism of life is exhausted; if a single thread of continuity is broken, the difference becomes as vast as heaven and earth. This refers to the blood of the main vessels. Blood and Qi are the major principles of medicine; students must examine them carefully!