《九天秘录》曰∶一阴一阳谓之道，阴阳不测之谓神。物中神而大者，天得一阳以守干道，地得
一阴以守坤道。物中神而明者，日得一阳魂以道应，月得一阴魂以道致。故夏至一阴自天来，若无真阳，
万物死也，不能焦枯。冬至一阳自地升，若无真阴，万物生也，不能滋润也。日有真阳，阳燧感而火
出；月无真阴，故方诸取而水绝。此天地日月至大至明，真阴真阳，岂人之不若是乎？
《西山记》曰∶肾，水也。水中生气，名曰真火。气中暗藏真一之水，是阴中有阳，阳中有阴也。
心，火也。火中生液，名曰真水。液中暗藏正阳之气，是阳中有阴，阴中有阳也。三华者，三阳。肾气乃
阴中之阳，丹中真气，则真阳中
之阳也，心液之气，乃阳中之阳。不说三阴也，所贵阴尽阳纯矣。
《玉皇圣胎诀》言∶人常降心火于下田，外境不入，泯绝狂虑；一气不散，委于气海。肾气不能
上升，其息渐少，纵出之悠悠，然减省也。故后圣有自然胎息矣，及达磨胎息至理，言人之气升，自
有走失，莫若内视诸世界，游玩自己天宫超清虚妙境。其法贵乎无漏，一念不生，一意不动。无漏，
则善果成；不动，而真圣见。而面壁九年，气无毫发走失，阴灵自外而身有身。东人不悟，乃掷钵
西归。故圣人曰∶真胎息也！及扁鹊解《灵枢》，以冬至之后，真铅积之一分，状如戏蕊而镇丹田。
令人鼻引清气，闭口不出，以定息二十四数，为火一两。四十五日，火进一十六两而炼就阳胎。又以
夏至之后，汞积之三分，状如抱卵而镇绛唇。亦以鼻引清气，闭口不出，以定息二十四数，为火一
两。四十五日，火进一十六两而炼阴息。以阴息投阳胎而生真气，真气生元神，神形合为一，
与天地齐年。离而为二，身外有身，而为羽客仙子，不在尘世，以返三岛十洲者也。及葛洪注
《胎息论》，曰∶凡胎息之要，如在母腹中。母呼即呼，母吸即吸。今人不达妙理，纵能闭之少时，
随口出之，喘息不已，非止不能留所闭之息，而又元气损虚，返为外来阳气所夺。若气未急之前，外
身自可停步少时，勿使大急。未气急之际，先鼻引清气一口，续后便以新取之气，换出旧闭急者之余
气也。故得夺住其气，积而形神清爽，可以除疗百病。曲留强住，亦非自然，所以为下等胎息。
真仙上圣而有三品之论也。鼻引口吐，可以去浮寒，逐客热，冲结滞，行经络。若定息，气血不
交，阴阳自媾。若定万息，气住神藏，大乘之功，不可言也。补气之
道，此为上矣。或咽气救饥渴，行气以壮肌肤，收气补下田，养气以返童颜，运气以益血脉，虽见小功，
终不及胎息之补气得力，功速且久也。
《九天秘录》说：一阴一阳的运行规律称为“道”，阴阳变化微妙不可预测的称为“神”。万物中神灵而伟大的，天得到一阳来坚守乾道（刚健之道），地得到一阴来坚守坤道（柔顺之道）。万物中神灵而光明的，太阳得到一阳魂以引导应和，月亮得到一阴魂以引导招致。所以夏至时一阴气从天降下，如果没有真阳，万物就会死亡，无法避免焦枯。冬至时一阳气从地上升起，如果没有真阴，万物虽然生长，却无法得到滋润。太阳有真阳，通过阳燧（古代取火工具）感应就能引出火；月亮没有真阴，所以通过方诸（古代取水工具）汲取就得不到水。这是天地日月最大最光明的道理，真阴真阳的道理，难道人不是也如此吗？
《西山记》说：肾属水。水中产生生气，名叫真火。气中暗藏真一之水，这就是阴中有阳，阳中有阴。心属火。火中产生津液，名叫真水。液中暗藏正阳之气，这就是阳中有阴，阴中有阳。所谓的“三华”是指三阳。肾气是阴中之阳，丹田中的真气则是真阳中的阳，心液的之气则是阳中之阳。这里不说三阴，因为珍贵的是阴尽而阳纯的状态。
《玉皇圣胎诀》说：人常将心火下降到下丹田（脐下三寸处），使外境不入内心，泯灭断绝狂乱的思虑；一气不散，汇聚于气海（下丹田）。肾气不能上升，呼吸逐渐减少，即使呼出也是悠长缓慢，这是一种减省的过程。所以后世圣人有了自然的胎息，以及达摩（菩提达摩）胎息的至高原理，说人的气上升，自然会有走失，不如内视各种境界，游玩自己体内的天宫超清虚妙境。这种方法贵在“无漏”（气息不泄露），一念不生，一意不动。无漏，则善果成就；不动，则真圣显现。达摩面壁九年，气息毫无毫发走失，阴灵从外部形成“身外身”。东方人不悟此理，于是掷钵西归（指达摩渡海去印度）。所以圣人说：这才是真正的胎息！等到扁鹊注解《灵枢》，提到冬至之后，真铅积累一分，形状像花蕊一样镇守丹田。让人鼻吸清气，闭口不出，以定息二十四次为一两火。四十五天后，火增加十六两从而炼成阳胎。又在夏至之后，汞积累三分，形状像抱卵一样镇守绛唇（嘴唇）。也用鼻吸清气，闭口不出，以定息二十四次为一两火。四十五天后，火增加十六两从而炼成阴息。用阴息投入阳胎而生出真气，真气生出元神，神与形合为一体，与天地同寿。若离为二，身外有身，成为羽客仙子，不在尘世，而是返回三岛十洲仙境的人。等到葛洪注释《胎息论》，说：大凡胎息的要领，就像在母腹中一样。母亲呼气我就呼气，母亲吸气我就吸气。现在的人不懂这奥妙，纵然能闭气一时，随即张口呼气，喘息不停，不仅不能留住所闭之气，反而元气受损虚弱，反被外来阳气所夺。如果在气未急促之前，身体可以暂时停止活动少许时间，不要使其过于急促。在气未急促之际，先鼻吸一口清气，随后便用新吸入的气，替换出旧闭气后剩余的急迫之气。因此能够留住其气，积累后形神清爽，可以治疗百病。强行曲留、强住，也不是自然之道，所以属于下等胎息。真正的仙上圣人有三种品级的论述。鼻吸口吐，可以去浮寒，驱逐客热，冲开结滞，运行经络。如果定息，气血不交，阴阳自会媾合。如果定万息，气住神藏，这是大乘的功效，不可言喻。补气之道，这是上等的了。或者咽气以救饥渴，行气以壮肌肤，收气补下田，养气以返童颜，运气以益血脉，虽然见到小功效，终究不及胎息补气得力，功效迅速且持久。
The *Jiutian Milu* (Secret Records of the Nine Heavens) states: The interplay of one Yin and one Yang is called the "Dao" (Way), and the unfathomable changeability of Yin and Yang is called "Shen" (Spirit/Divinity). Among all things, those that are spiritual and great: Heaven obtains one Yang to uphold the Qian Dao (Primal Creative Principle), and Earth obtains one Yin to uphold the Kun Dao (Receptive Principle). Among all things, those that are spiritual and bright: The Sun obtains one Yang Soul to guide and respond, and the Moon obtains one Yin Soul to guide and attract. Therefore, at the Summer Solstice, one Yin descends from Heaven; without True Yang, all things would die and cannot avoid withering and drying up. At the Winter Solstice, one Yang rises from Earth; without True Yin, although all things grow, they cannot be nourished and moistened. The Sun possesses True Yang, and through the Yang Sui (ancient fire-gathering mirror), fire is induced by resonance; the Moon lacks True Yin, therefore, through the Fang Zhu (ancient water-gathering vessel), water cannot be obtained. This is the principle of Heaven, Earth, Sun, and Moon being the greatest and brightest; regarding True Yin and True Yang, are humans not also like this?
The *Xishan Ji* (Records of Western Mountain) states: The Kidney belongs to Water. Within Water arises Sheng Qi (Vital Qi), named Zhen Huo (True Fire). Hidden within Qi is Zhenyi Zhi Shui (Water of True Unity); this is Yin containing Yang, and Yang containing Yin. The Heart belongs to Fire. Within Fire arises Ye (Fluids/Juice), named Zhen Shui (True Water). Hidden within Fluids is Zheng Yang Zhi Qi (Righteous Yang Qi); this is Yang containing Yin, and Yin containing Yang. The so-called "San Hua" (Three Flowers/Essences) refers to Three Yangs. Kidney Qi is Yang within Yin; the True Qi in the Dantian (Elixir Field) is Yang within True Yang; the Qi of Heart Fluid is Yang within Yang. It does not speak of Three Yins, because what is valued is the state where Yin is exhausted and Yang is pure.
The *Yuhuang Shengtai Jue* (Secret Formula of the Jade Emperor's Sacred Fetus) states: One should often descend Heart Fire to the Lower Tian (Lower Elixir Field, located three inches below the navel), preventing external realms from entering the mind, and extinguishing delirious thoughts; let one Qi remain undissipated and settle in the Qi Hai (Sea of Qi, synonymous with Lower Dantian). When Kidney Qi cannot rise, respiration gradually decreases; even when exhaled, it is leisurely and slow, representing a process of reduction. Thus, later sages attained natural Taixi (Fetal Breathing), and reached the ultimate principle of Bodhidharma's Taixi, stating that when human Qi ascends, it naturally leaks; it is better to practice Neishi (Inner Vision) of various realms, roaming within one's own Heavenly Palace in the transcendent and void wondrous state. This method values "Wulou" (No Leakage, i.e., breath retention without escape), having no arising thought, and unmoving intent. No leakage leads to the accomplishment of good fruits; immobility allows the appearance of the True Sage. Bodhidharma faced the wall for nine years, his Qi leaking not a hair's breadth, forming a "body outside the body" from Yin Spirit originating externally. Those in the East did not comprehend this, hence he threw his bowl and returned West (to India). Thus the Sage says: This is true Taixi! When Bian Que annotated the *Lingshu* (Spiritual Pivot), it was mentioned that after the Winter Solstice, Zhenqian (True Lead) accumulates by one part, resembling a flower bud settling in the Dantian. One inhales clear Qi through the nose, closes the mouth without exhaling, counting twenty-four settled breaths as one liang (unit of heat/fire). After forty-five days, the fire increases by sixteen liang, refining the Yang Tai (Yang Fetus). Then, after the Summer Solstice, Gong (Mercury) accumulates by three parts, resembling an egg being brooded, settling on the Jiangchun (Crimson Lips/Mouth). Similarly, inhale clear Qi through the nose, close the mouth without exhaling, counting twenty-four settled breaths as one liang of fire. After forty-five days, the fire increases by sixteen liang, refining the Yin Xi (Yin Breath). By casting Yin Xi into Yang Tai, True Qi is born; from True Qi, Yuanshen (Original Spirit) is generated. Spirit and Form merge into one, sharing the lifespan of Heaven and Earth. If separated into two, there is a body outside the body, becoming a Feathered Guest or Immortal Fairy, no longer in the mortal world, but returning to the Three Islands and Ten Continents (immortal realms). When Ge Hong annotated the *Taixi Lun* (Treatise on Fetal Breathing), he said: The essence of Taixi is like being in the mother's womb. When the mother exhales, I exhale; when the mother inhales, I inhale. People today do not understand this profound principle; even if they can hold their breath for a short time, they immediately open their mouths to exhale, panting continuously. This not only fails to retain the held breath but also damages and empties Yuan Qi (Primordial Qi), allowing external Yang Qi to seize it. Before the breath becomes urgent, one may stop physical activity for a short while, avoiding excessive urgency. Before the breath becomes urgent, first inhale one mouthful of clear Qi through the nose, then use the newly inhaled Qi to replace the residual air from the previously held, urgent breath. Thus, one can retain the Qi, accumulate it until the form and spirit are refreshed, which can cure hundred diseases. Forcing retention or holding is not natural, thus constituting inferior Taixi. True Immortals and Supreme Sages discuss three grades. Inhaling through the nose and exhaling through the mouth can dispel floating cold, drive away pathogenic heat, break stagnation, and circulate meridians. If one settles the breath, Qi and Blood do not mix, and Yin and Yang naturally couple. If one settles ten thousand breaths, Qi remains still and Spirit hides, achieving the merit of the Great Vehicle, which cannot be described. Regarding the way of tonifying Qi, this is the supreme method. Or, swallowing Qi to relieve hunger and thirst, circulating Qi to strengthen muscles and skin, gathering Qi to tonify the Lower Tian, nurturing Qi to restore youthful complexion, moving Qi to benefit blood vessels; although small merits are seen, none compare to the efficacy of Taixi in tonifying Qi, which is rapid and enduring.