内与外对，壮与衰对。壮与衰较，壮可久也。内与外较，外勿略也。内壮言坚，外壮言勇，坚
而能勇是真勇也，勇而能坚是真坚也，坚坚勇勇，勇勇坚坚，乃成万劫不化之身，方是金刚之体矣。
凡炼内壮，其则有三∶一曰守此中道，守中者，专于积气也。积气者，专于眼耳鼻舌身意也。其下手之
要，妙于用揉，其法详后。凡揉之时，宜解襟仰卧，手掌着处，其一掌下胸腹之间，即名曰中。惟
此中乃存气之地，应须守之。守之之法，在乎含其眼光，凝其耳韵，匀其鼻息，缄其口气，逸其身劳，
锁其意驰，四肢不动，一念冥心，先存想其中道，后绝其诸妄念，渐至如一不动，是名曰守，斯为合
式。盖揉在于是，则一身之精气神俱注于是，久久积之，自成庚方一片矣。设如杂念纷纭，驰想世务，
神气随之而不凝，则虚其揉矣，何益之有。二曰，勿他想，人身之中，精气神血不能自主，悉听于意，
意行则行，意止则止。守中之时，意随掌下，是为合式。若或驰意于各肢，其所凝积精气与神，随
即走散于各肢，即成外壮，而非内壮矣。揉而不积，又虚其揉矣，有何益哉。三曰，待其充周。凡揉
与守，所以积气，气既积矣，精神血脉悉皆附之。守之不驰，揉之且久，气惟中蕴而不旁溢，气积
而力自积，气充而力自周。此气即孟子所谓，至大至刚，塞乎天地之间者，是吾浩然之气也。设未及
充周，驰意外走，散于四肢，不惟外壮不全，而内壮亦属不坚，则两无是处矣。
般刺密谛曰∶人之初生，本来原善。若为情欲杂念分
去，则本来面目，一切抹倒。又为眼耳鼻舌身意，分损灵犀，蔽其慧性，以致不能悟道，所以达摩大师
面壁少林九载者，是不纵耳目之欲也。耳目不为欲纵，猿马自被其锁绊矣。故达摩大师得斯真法，始能
只履西归，而登正果也。此篇乃达摩佛祖心印，先基真法，在守中一句，其用在含其眼光七旬。若能
如法行之，则虽愚必明，虽柔必强，极乐世界，可立而登矣。
内与外相对，壮与衰相对。比较壮与衰，壮是可以持久的。比较内与外，对外部（锻炼）不可轻视。内壮强调坚实，外壮强调勇猛，坚实而能勇猛才是真勇猛，勇猛而能坚实才是真坚实，既坚实又勇猛，才能成就万劫不毁之身，这才是金刚之体。
凡是修炼内壮，其法则有三条：一是坚守中道。所谓守中，就是专注于积聚气。积聚气，关键在于眼、耳、鼻、舌、身、意这六根。下手的关键，妙在运用揉法，具体方法详见后文。凡是在揉的时候，应当解开衣襟仰卧，手掌接触的地方，其中一掌位于胸腹之间，这就叫做“中”。只有这个部位是存气的地方，必须坚守它。坚守的方法，在于收敛眼光，凝注耳韵，均匀鼻息，闭缄口气，使身体安逸而不劳累，锁住意念使其不驰散，四肢不动，一心冥思，先想象中道的存在，然后断绝各种妄念，逐渐达到专一无二、不动心的状态，这就叫“守”，这才符合规范。因为揉法作用于此处，全身的精、气、神都会汇聚于此，久而久之积聚起来，自然会在中宫形成一片庚金之气（指肺金之气或正气）。如果杂念纷飞，心思驰骛于世俗事务，神气随之涣散而不能凝聚，那么揉法就白费了，有什么益处呢？
二是不要有其他的念头。人身中的精、气、神、血不能自主，完全听从意念的支配，意念到哪里，它们就跟到哪里；意念停止，它们也就停止。在守中的时候，意念跟随手掌下方，这才符合规范。如果意念驰散到各个肢体，那么所凝聚积聚的精气和神，随即就会分散到各个肢体，这样就变成了外壮，而不是内壮了。只揉而不积聚，也是白费揉功，有什么益处呢？
三是等待气充满周身。凡是用揉法和守法，都是为了积聚气。气既然积聚了，精神血脉都依附于它。守中时意念不驰散，揉练时间长久，气只蕴蓄在中部而不旁溢，气积聚了力量自然积蓄，气充满了力量自然周遍全身。这种气就是孟子所说的，至大至刚，充满于天地之间的浩然之气。如果气还没有充满周身，意念就驰散向外，分散到四肢，不仅外壮不完整，内壮也不坚固，那就两头落空了。
般刺密谛说：人刚出生时，本性原本是善的。如果被情欲和杂念分去，那么本来面目就被一切抹去了。又被眼、耳、鼻、舌、身、意所分损灵犀，遮蔽了慧性，以致不能悟道。所以达摩大师在少林寺面壁九年，就是不放纵耳目之欲。耳目不被欲望放纵，猿马般的意念自然就被锁住了。因此达摩大师得到了这个真法，才能只履西归，修成正果。这篇文字乃是达摩佛祖的心印，是筑基的真法，关键就在“守中”这一句，其作用在于“含其眼光”等七项功夫。如果能按照方法实行，那么即使愚笨也必变聪明，即使柔弱也必变强壮，极乐世界，可以立刻登临了。
Internal and external are opposites; strength and weakness are opposites. Comparing strength with weakness, strength can endure. Comparing internal with external, the external should not be neglected. Internal strength emphasizes firmness, while external strength emphasizes bravery. Firmness combined with bravery constitutes true bravery, and bravery combined with firmness constitutes true firmness. Only when one is both firm and brave can one achieve a body that remains uncorrupted through countless kalpas, which is then considered a Diamond Body (Jingang Zhi Ti).
There are three principles for cultivating internal strength: First, guard the Middle Way (Zhong Dao). Guarding the middle refers to focusing on accumulating Qi (vital energy). Accumulating Qi focuses on the six sense organs: eyes, ears, nose, tongue, body, and mind. The key to beginning practice lies in the subtlety of kneading (Rou). The method is detailed later. When kneading, one should unbutton the clothes and lie supine. The place where the palm rests, specifically between the chest and abdomen under one palm, is named "the Middle" (Zhong). This is the location where Qi is stored and must be guarded. The method of guarding involves restraining the gaze from the eyes, condensing the auditory awareness from the ears, regulating the breath from the nose, sealing the mouth's speech, keeping the body at ease without labor, locking the mind to prevent it from wandering, keeping the four limbs still, and focusing the mind in meditation. One should first visualize the Middle Way, then eliminate all delusional thoughts, gradually reaching a state of undivided immobility. This is called "guarding," and it conforms to the proper form. Since kneading occurs here, the essence, Qi, and spirit of the whole body converge here. Over time, through accumulation, a patch of Geng Metal Qi (representing righteous Qi or Lung Qi) will naturally form. If scattered thoughts arise and the mind wanders to worldly affairs, the spirit and Qi will follow and fail to condense; thus, the kneading becomes futile, yielding no benefit.
Second, do not entertain other thoughts. The essence, Qi, spirit, and blood within the human body cannot act autonomously; they obey the intent entirely. Where the intent goes, they go; where the intent stops, they stop. During the guarding of the middle, the intent should follow the area beneath the palm, which conforms to the proper form. If the intent wanders to various limbs, the condensed and accumulated essence, Qi, and spirit will immediately disperse to those limbs, resulting in external strength rather than internal strength. Kneading without accumulation is also futile, yielding no benefit.
Third, wait until the Qi fills the entire system. Both kneading and guarding are used to accumulate Qi. Once Qi is accumulated, the spirit, blood, and vessels attach to it. By guarding without letting the intent wander and kneading for a long time, the Qi remains contained in the center without overflowing sideways. As Qi accumulates, strength naturally accumulates; as Qi fills up, strength naturally circulates throughout the body. This Qi is what Mencius described as "supremely large and supremely strong, filling heaven and earth," known as our Haoran Zhi Qi (Noble Spirit). If the Qi has not yet filled the system and the intent wanders outward, dispersing into the four limbs, neither external strength nor internal strength will be complete or firm, resulting in failure in both aspects.
Ban Ci Mi Di stated: At birth, human nature is originally good. If this is divided by desires and scattered thoughts, the original face is completely obscured. Furthermore, the six sense organs divide and damage the spiritual clarity, obscuring wisdom, thereby preventing the realization of the Dao. Therefore, Master Bodhidharma sat facing the wall at Shaolin for nine years, not indulging the desires of the eyes and ears. With the eyes and ears not indulged by desire, the monkey-like and horse-like mind (metaphors for restless thoughts) are naturally shackled. Thus, Master Bodhidharma obtained this true method, enabling him to return west with only one shoe and attain enlightenment. This passage is the Mind Seal of Bodhidharma Buddha, the true method for establishing the foundation. Its core lies in the phrase "guarding the middle," and its application lies in the seven items starting with "restraining the gaze." If one practices according to the method, even the foolish will become enlightened, and even the weak will become strong. The Pure Land can be attained instantly.