凡人一身有经脉、络脉，直行曰经，旁支曰络。经凡十二∶手之三阴、三阳，足之三阴、三阳是也。
络凡十五∶乃十二经各有一别络，而脾又有一大络，并任、督二络为十五也。（难经作阴络，阳络）共二十七气，
相随上下，如泉之流，如日月之行，不得休息。故阴脉营于五脏，阳脉营于六腑，阴阳相贯，如环无端，
莫知其纪，终而夏始。其流溢之气，入于奇经，转相灌溉，内温脏腑，外濡腠理。奇经凡八脉，不拘制于
十二正经，无表里配合，故谓之奇。盖正经犹夫沟渠，奇经犹夫湖泽，正经之脉隆盛，则溢于奇经。故
秦越人比之∶天雨降下，沟渠溢满， 霈妄行，流于湖泽，此发灵、素未发之秘旨也。八脉散在群书者，
略而不悉。医不知此，罔探病机；仙不知此，难安炉鼎。时珍不敏，参考诸说，萃集于左，以备学仙、医
者，筌蹄之用云。
奇经八脉者∶阴维也、阳维也、阴跷也、阳跷也、冲也、任也、督也、带也。阳维起于诸阳之会，
由外踝而上行于卫分；阴维起于诸阴之交，由内踝而上行于营分，所以为一身之纲维也。阳跷起于跟中，
循外踝上行于身之左右；阴跷起于跟中，循内踝上行于身之左右，所以使机关之跷捷也。督脉起于会阴，
循背而行于身之后，为阳脉之总督，故曰阳脉之海；任脉起于会阴，循腹而行于身之前，为阴脉之承任，
故曰阴脉之海；冲脉起于会阴，夹脐而行，直冲于上，为诸脉之冲要，故曰十二经脉之海，带脉则横围
于腰，状如束带，所以总约诸脉者也。是故阳维主一身之表，阴维主一身之里，以乾坤言也。阳跷主一身
左右之阳，阴跷主一身左右之阴，以东西言也。督主身后之阳，任、冲主身前之阴，以南北言也。带脉横
束诸脉，以六合言也。是故医而知乎八脉，则十二经、十五络之大旨得矣。仙而知乎八脉，则虎龙升降
玄牝幽微之窍妙得矣。
In the human body, there are Jing (Main) Meridians and Luo (Collateral) Vessels. Those that run straight are called Jing Meridians, while those that branch off are called Luo Vessels. There are twelve Jing Meridians in total: these are the three Yin and three Yang meridians of the hand, and the three Yin and three Yang meridians of the foot.
There are fifteen Luo Vessels in total: each of the twelve Jing Meridians has one major collateral, plus one large collateral from the Spleen, along with the collaterals of the Ren Mai (Conception Vessel) and Du Mai (Governing Vessel), making fifteen in all. (The *Nan Jing* refers to them as Yin Collaterals and Yang Collaterals). Together, they form twenty-seven Qi streams, flowing up and down continuously like a spring or the movement of the sun and moon, never resting. Thus, Yin Meridians nourish the Zang Organs, and Yang Meridians nourish the Fu Organs. Yin and Yang interconnect like a circle without beginning or end, unknown in its cycle, ending only to begin again. The overflowing Qi enters the Eight Extraordinary Vessels, irrigating each other, warming the internal organs, and moistening the Cou Li (skin texture and pores). The Eight Extraordinary Vessels are not constrained by the Twelve Regular Meridians and lack interior-exterior pairings, hence they are called "Extraordinary" (Qi). Generally, the Regular Meridians are like ditches and canals, while the Extraordinary Vessels are like lakes and marshes. When the Qi in the Regular Meridians is abundant, it overflows into the Extraordinary Vessels. Therefore, Qin Yue-ren (Bian Que) compared this to: when rain falls from heaven and the ditches overflow, the water spreads wildly into the lakes. This elucidates the secret principles unmentioned in the *Ling Shu* and *Su Wen*. The descriptions of the Eight Vessels scattered in various books are brief and incomplete. If physicians do not understand this, they cannot probe the pathogenesis; if cultivators do not understand this, they cannot stabilize the furnace and tripod (metaphors for the body in internal alchemy). Though I, Lizhen, am not talented, I have consulted various theories and compiled them here for the use of those studying alchemy and medicine as a stepping stone.
The Eight Extraordinary Vessels are: Yin Wei Mai, Yang Wei Mai, Yin Qiao Mai, Yang Qiao Mai, Chong Mai, Ren Mai, Du Mai, and Dai Mai. The Yang Wei Mai originates at the convergence of all Yang meridians, ascending from the lateral malleolus through the Wei Fen (defensive Qi level); the Yin Wei Mai originates at the intersection of all Yin meridians, ascending from the medial malleolus through the Ying Fen (nutritive Qi level), thereby serving as the framework for the whole body. The Yang Qiao Mai originates in the heel, following the lateral malleolus upward on both sides of the body; the Yin Qiao Mai originates in the heel, following the medial malleolus upward on both sides of the body, thereby enabling the agility of joints and movements. The Du Mai originates at Huiyin (CV1), follows the back, and runs along the posterior aspect of the body, acting as the commander of all Yang meridians, thus called the "Sea of Yang Meridians"; the Ren Mai originates at Huiyin (CV1), follows the abdomen, and runs along the anterior aspect of the body, acting as the bearer of all Yin meridians, thus called the "Sea of Yin Meridians"; the Chong Mai originates at Huiyin (CV1), runs alongside the umbilicus, and rushes directly upward, being the crucial passage for all meridians, thus called the "Sea of the Twelve Regular Meridians"; the Dai Mai encircles the waist horizontally, resembling a belt, thereby binding and regulating all meridians. Therefore, the Yang Wei Mai governs the exterior of the body, and the Yin Wei Mai governs the interior, analogous to Heaven and Earth. The Yang Qiao Mai governs the Yang on both sides of the body, and the Yin Qiao Mai governs the Yin on both sides, analogous to East and West. The Du Mai governs the Yang at the back, while the Ren and Chong Mai govern the Yin at the front, analogous to North and South. The Dai Mai binds the meridians horizontally, analogous to the Six Directions. Thus, if a physician understands the Eight Vessels, they grasp the main purport of the Twelve Meridians and Fifteen Collaterals; if a cultivator understands the Eight Vessels, they comprehend the profound mysteries of the ascent and descent of the Tiger and Dragon, and the subtle apertures of the Mysterious Female.