夫人之一身，内而五脏六腑，外而四肢百骸；内而精气与神，外而筋骨与肉，共成一身也。如脏
腑之外，筋骨主
之，筋骨之外，肌肉主之；肌肉之内，血脉主之，周身上下，动摇活泼者，此又主之于气也。是故
修养之功，全在培养血气者，为大要也。即如天之生物，亦各随阴阳之所至而百物生焉，况于人生乎？况于
修炼乎？且夫精气神为无形之物也，筋骨肉乃有形之身也，此法必先炼有形者为无形之佐，培无形者为有
形之辅，是一而二，二而一者也。
若专培无形而弃有形，则不可。专炼有形而弃无形，更不可。所以有形之身必得无形之气相倚，
而不相违，乃成不坏之体。设相违而不相倚，则有形者亦化而无形矣。是故炼筋必须炼膜，炼膜必须炼
气。然而炼筋易而炼膜难，炼膜难而炼气更难也。先从极难极乱处立定脚跟，后向不动不摇处认斯真法。
务培其元气，守其中气，保其正气、获其肾气，养其肝气，调其肺气，理其脾气，升其清气，降其
浊气，闲其邪恶不正之气，勿伤于气，勿逆于气，勿忧思悲怒以损其气。使气清而平，平而和，和而畅
达，能行于筋，串于膜，以至通身灵动，无处不行，无处不到。气至则膜起，气行则膜张。能起能张，则
膜与筋齐坚固矣。如炼筋不炼膜，而膜无所主，炼膜不炼筋，而膜无所根据。炼筋炼膜而不炼气，而筋
膜泥而不起，炼气而不炼筋膜，而气 而不能宣达流串于筋络。气不能流串，则筋不能坚固，此所谓参
互其用，错综其道也。俟炼至筋起之后，必宜倍加功力，务使周身之膜皆能腾起，与筋齐坚着于皮，
固于内，始为子母各当，否则筋坚无助，比如植物无土培养，岂曰全功也哉？！
般刺密谛曰∶此篇言易筋以炼膜为先，炼膜以炼气为主。然此膜人多不识，不可为脂膜之膜，乃筋膜
之膜也。脂膜腔中物也！筋膜骨外物也。筋则联系肢骸，膜则包贴骸骨。筋与膜较，膜软于筋，肉与膜较，
膜劲于肉，膜居肉之内，骨
之外，包骨衬肉之物也。其状若此，行此功者，必使气串于膜间，护其骨，壮其筋，合为一体，乃曰全功。
人的整个身体，内部包括五脏六腑，外部包括四肢百骸；内部包含精、气、神，外部包含筋骨和肌肉，共同构成了一个完整的身体。在脏腑之外，由筋骨来主导支撑；在筋骨之外，由肌肉来包裹覆盖；在肌肉之内，由血脉来运行流通；周身上下之所以能够动摇活泼，这又是由“气”来主宰的。因此，修养功夫的关键，全在于培养血气，这是最重要的要点。
就像上天化生万物，也是随着阴阳所至而万物生长，何况是人的生命呢？何况是修炼人体呢？况且精、气、神属于无形的存在，筋骨、肉属于有形的躯体。这种方法必须先炼化有形的躯体作为无形之物的辅助，培育无形的精气神作为有形躯体的辅佐，这是一体两面、二合一的关系。
如果专门培育无形之物而抛弃有形之身，是不行的；专门炼化有形之身而抛弃无形之气，更是不行的。所以，有形的身体必须得到无形之气的依附，而不相违背，才能成就坚固不坏的身体。假如两者相违背而不相互依附，那么有形的身体也会化为乌有。因此，炼筋必须同时炼膜，炼膜必须同时炼气。然而，炼筋容易而炼膜难，炼膜难而炼气更难。首先要从极难极乱的地方站稳脚跟，然后向不动不摇的境界去领悟真正的法门。务必培养元气，守住中气，保护正气，获取肾气，养护肝气，调理肺气，理顺脾气，升发清气，降下浊气，远离邪恶不正之气，不要损伤气，不要逆乱气，不要因忧思悲怒而损耗气。使气清澈而平和，平和而和谐，和谐而畅达，能够运行于筋，串联于膜，以至于全身灵动，无处不行，无处不到。气到达则膜鼓起，气运行则膜张开。能够鼓起能够张开，那么膜与筋就一起坚固了。如果只炼筋不炼膜，膜就没有主宰；只炼膜不炼筋，膜就没有依托。既炼筋又炼膜却不炼气，那么筋和膜就会僵硬而不能起效；只炼气而不炼筋膜，那么气就不能宣通流串于筋络。气不能流串，筋就不能坚固，这就是所谓的互相为用，错综其道。等到炼到筋起之后，必须加倍功力，务必使全身的膜都能腾起，与筋一样坚固附着于皮内，固守于体内，这才算是子母各当（主次得当），否则筋虽然坚固却缺乏辅助，比如植物没有土壤培养，怎么能说是完成了全部功夫呢？！
般刺密谛说：这篇经文讲易筋以炼膜为先导，炼膜以炼气为主旨。然而这种“膜”，人们大多不认识，它不是指脂膜，而是指筋膜。脂膜是在腔体中的东西！筋膜是在骨骼外面的东西。筋负责联系肢体骨骼，膜负责包贴骸骨。筋与膜相比，膜比筋软；肉与膜相比，膜比肉劲（坚韧）。膜居于肉之内，骨之外，是包骨衬肉的东西。其形态如此，练习此功的人，必须使气串联于膜间，保护骨骼，强壮筋骨，合为一体，才叫作完成全部功夫。
The human body, internally comprising the five zang organs and six fu organs, and externally consisting of the four limbs and hundred bones; internally containing jing (essence), qi (vital energy), and shen (spirit), and externally composed of sinews (tendons/ligaments) and flesh (muscles), together form a complete entity. Outside the zang-fu organs, sinews and bones provide the main support; outside the sinews and bones, muscles provide the covering; inside the muscles, blood vessels govern circulation; the ability of the entire body to move and be agile is primarily governed by qi. Therefore, the essence of cultivation lies entirely in nourishing blood and qi, which is the most crucial aspect. Just as heaven generates all things according to the arrival of yin and yang, how much more so for human life? And even more so for physical cultivation? Moreover, jing, qi, and shen are formless entities, while sinews, bones, and flesh are formed bodies. This method must first refine the formed body as an assistant to the formless, and cultivate the formless as a support for the formed; this is one becoming two, and two becoming one.
If one solely cultivates the formless while abandoning the formed, it is inadmissible. If one solely refines the formed while abandoning the formless, it is even less acceptable. Thus, the formed body must rely on the formless qi without contradiction to achieve an indestructible physique. If they contradict and do not rely on each other, the formed body will also transform into formlessness. Therefore, refining sinews requires refining membranes (fascia); refining membranes requires refining qi. However, refining sinews is easy while refining membranes is difficult; refining membranes is difficult while refining qi is even more so. One must first take a firm stand in the most difficult and chaotic places, then seek the true method in the state of immobility and unshakability. One must diligently nourish yuan qi (original qi), guard zhong qi (middle qi), protect zheng qi (upright qi), acquire shen qi (kidney qi), nurture gan qi (liver qi), regulate fei qi (lung qi), manage pi qi (spleen qi), ascend qing qi (clear qi), descend zhuo qi (turbid qi), avoid xie e qi (evil/unwholesome qi), do not injure qi, do not reverse qi, and do not damage qi through worry, thought, grief, or anger. Let qi become clear and calm, calm and harmonious, harmonious and smooth-flowing, able to travel through sinews and thread through membranes, until the whole body becomes agile, moving everywhere and reaching everywhere. When qi arrives, the membrane rises; when qi moves, the membrane expands. If it can rise and expand, the membrane and sinews become equally solid. If one refines sinews but not membranes, the membranes have no master; if one refines membranes but not sinews, the membranes have no foundation. If one refines sinews and membranes but not qi, the sinews and membranes become stiff and ineffective; if one refines qi but not sinews and membranes, qi cannot circulate freely through the meridians. If qi cannot circulate, sinews cannot become solid. This is what is meant by mutual utility and intricate interconnection. After refining until the sinews rise, one must double the effort, ensuring that the membranes of the entire body can rise, attaching firmly to the skin like the sinews, and securing internally. Only then are the mother and child aspects properly balanced; otherwise, although the sinews are solid, they lack assistance. It is like plants without soil for cultivation—how can this be considered complete achievement?!
Ban Ci Mi Di (Paramaguru) said: This chapter states that Yi Jin Jing (Muscle/Tendon Changing Classic) begins with refining membranes, and refining membranes focuses on refining qi. However, this "membrane" is often unrecognized by people; it is not the fatty membrane (adipose tissue), but the fascial membrane. The fatty membrane exists within body cavities! The fascial membrane exists outside the bones. Sinews connect the limbs and bones, while membranes wrap around the skeletal bones. Comparing sinews and membranes, membranes are softer than sinews; comparing flesh and membranes, membranes are tougher than flesh. Membranes reside inside the flesh and outside the bones, serving as the substance that wraps bones and lines flesh. With such a structure, practitioners must ensure qi threads between the membranes, protecting the bones and strengthening the sinews, integrating them into one unit, which is called complete achievement.