人之元气，一太极也。太极动而生阳，静而生阴。阳动则为火，阴静则为水。水
者，精也。精者，元气之体所以立也，火者，神也。神者，元气之用所以行也。阳动
阴静，初生精神，次生魂魄意，以配五行。五行立而五性具，五性具而七情生。夫水
者，阴也。火者，阳也。一为肾，一属命门，命门谓之神门，男子藏精，女子系胞，
元气之根本，精神之所舍也。故肾命门为元气之原，而居至阴之下，左尺肾水之真阴。
则生左关肝木，肝木则生左寸之心火。右尺命门火之元阳，则生右关脾土，脾土则生右
寸之肺金，自下而生上，此先天之元气也。至于火生土，主生水，复自上而下，此后天
之元气也。先天之元气，由无形以肇生五行，后天之元气，从有形之五行，以环运先
天，阴阳无形之气，阴阳合德，而生魂魄神志意之神，爰有喜怒忧思悲恐惊之情，此其
性真之七情也。若过极则反损先天阴阳之气。
后天阴阳有形之气，何以别之？受生之初，即禀母脾胃之谷气，以养其形，是脾胃
之谷气，实始于先天无形之阴阳，而更化生乎后天有形之气血也。苟从饮食劳役所伤，
则损后天阴阳之气，而肾命门之真阴元阳不足，固不能为十二经之气血以立天元，脾胃
之谷神不充，更不能为肾命门之真阴元阳以续命脉，而先后天浓薄之所由也。以先天元
阴受伤，神多昏昧，至夜便多不安，及将睡时惊恐不寐，寐则怕人而不宁，心慌惊跳，
神魂荡漾，此为神思间无形之火动也。治宜大补真阴，兼以安神，则火自降，而神自
清。然先天无形元阴之气不足，切不可用参术黄 ，惟地黄丸补真阴真阳之属，可以填
之，盖甘温但补五脏之阳气，而甘寒则补五脏之真阴，然甲补阴药而不愈者，乃功之未
到，而虚之未回，药非百数，功非岁月，则不能挽回也。然此惟不服药便觉火动不安
者，是其验也。
先天无形元气之阴者，即我肾水之母气，禀受元精之祖气也。其真阴之本体，则
深藏于左肾之中，其真阴之妙用，则默运于精神之内，故曰无形也。苟有所伤其真阴，
则令精神恍惚，夜卧不安，目则KT KT ，羞明怕日，或恶人与火，喜静畏动，所喜所见皆
阴也。此由父母多欲，素伤肾气，或因交感之际，偶从七情损其真阴，及至后天，已之
色欲七情，复不樽节，生后并伤，欲不虚荣疾病，焉可得乎？治疗之法，当温存内养，
保其残败之阴，补益阴阳，助其生长之力然阳火易救，阴水难求，故先天元阴之真水
不足，自非岁月计功，不能干旋，盖一星之火，能应万顷之山，一杯水，难救车薪之火也。
人的元气，就是太极。太极运动而产生阳，静止而产生阴。阳动则表现为火，阴静则表现为水。水，就是精。精，是元气的本体，用来确立生命的基础；火，就是神。神，是元气的功用，用来运行生命活动。阳动阴静，初生精神，进而产生魂、魄、意，以配合五行。五行确立而五性具备，五性具备而七情产生。所谓水，属阴；火，属阳。一者归于肾，一者属于命门。命门被称为神门，男子在此藏精，女子在此系胞（连接子宫），这是元气的根本，精神寄托的地方。所以肾和命门是元气的源头，居于至阴之下，对应左尺脉的肾水真阴。由此生发左关脉的肝木，肝木又生发左寸脉的心火。右尺脉的命门火之元阳，生发右关脉的脾土，脾土又生发右寸脉的肺金。自下而生上，这是先天的元气。至于火生土，土主生水，又自上而下循环，这是后天的元气。先天的元气，由无形之气肇始生成五行；后天的元气，从有形的五行出发，来环运滋养先天。阴阳无形之气，阴阳合德，而产生魂、魄、神、志、意的精神活动，于是有了喜、怒、忧、思、悲、恐、惊的情感，这就是本性真实的七情。如果情感过度极端，就会反过来损伤先天的阴阳之气。
后天的阴阳有形之气，如何区分呢？在受孕之初，就禀受母亲脾胃的水谷之气，来养育形体。因此，脾胃的水谷之气，实际上始于先天的无形阴阳，并进一步化生出后天的有形气血。假如因为饮食不节或劳役过度而受伤，就会损伤后天的阴阳之气，导致肾和命门的真阴、元阳不足。这固然不能为十二经脉的气血建立天元的根基，脾胃的水谷之神不充盈，更不能为肾和命门的真阴、元阳延续命脉，这就是先后天元气浓薄差异的原因所在。如果先天的元阴受伤，精神大多昏昧，到了夜晚便多不安宁，以及将要入睡时惊恐失眠，睡着后怕人而不安宁，心慌惊跳，神魂荡漾，这是因为神思之间无形的火在妄动。治疗应当大补真阴，兼以安神，那么火自然下降，神自然清明。然而，如果是先天的无形元阴之气不足，切不可使用人参、白术、黄芪等药，只有像地黄丸那样补益真阴真阳的药物，才可以填补它。大概甘温的药只补五脏的阳气，而甘寒的药才补五脏的真阴。然而，服用补阴药却不见痊愈的，是因为药效还未到位，虚损还未恢复，药物数量不够多，疗程不够长，就不能挽回病情。当然，这种情况只有在不服药就觉得火动不安时，才是其确切的验证。
先天无形元气中的阴，就是我肾水的母气，禀受元精的祖气。它的真阴本体，深藏在左肾之中；它的真阴妙用，则在精神内部默默运作，所以说它是无形的。如果有所损伤其真阴，就会导致精神恍惚，夜间睡眠不安，眼睛干涩不适，畏光怕日，或者厌恶人与火光，喜欢安静害怕活动，所喜欢的所见到的都是阴性的事物。这是由于父母房事过多，素来损伤肾气，或者在交感之际，偶尔因七情损伤了真阴，等到后天，自己又不知节制色欲和七情，出生后一并受损，想要没有虚荣和疾病，怎么可能呢？治疗的方法，应当温和地内养，保护其残败的阴液，补益阴阳，助其生长的力量。然而阳火容易救治，阴水难以求得，所以先天的元阴真水不足，如果不是按岁月来计算疗效，是不能扭转局面的。大概一点星星之火，能应对万顷山林的大火；一杯水，很难扑灭车薪（一车柴草）燃烧的火势。
Human Yuan Qi (Original Qi) is the Taiji (Supreme Ultimate). When Taiji moves, Yang (Active/Expansive energy) is generated; when it is still, Yin (Static/Contractive energy) is generated. Movement of Yang manifests as Fire (Huo), and stillness of Yin manifests as Water (Shui). Water is Jing (Essence). Jing is the substance of Yuan Qi, upon which life is established; Fire is Shen (Spirit). Shen is the function of Yuan Qi, through which life activities are conducted. Through Yang movement and Yin stillness, Jing and Shen are initially generated, followed by Hun (Ethereal Soul), Po (Corporeal Soul), and Yi (Intellect), corresponding to the Five Elements (Wu Xing). Once the Five Elements are established, the Five Natures (Wu Xing) are complete; once the Five Natures are complete, the Seven Emotions (Qi Qing) arise. Water belongs to Yin; Fire belongs to Yang. One resides in the Kidney (Shen), and the other in the Mingmen (Gate of Life). The Mingmen is also called the Gate of Spirit. In men, it stores Jing; in women, it connects to the Bao (Uterus). It is the root of Yuan Qi and the abode of Jing and Shen. Therefore, the Kidney and Mingmen are the source of Yuan Qi, residing in the lowest part of extreme Yin, corresponding to the True Yin of Kidney Water at the Left Chi pulse position. From this arises Liver Wood at the Left Guan position; Liver Wood generates Heart Fire at the Left Cun position. The Original Yang of Mingmen Fire at the Right Chi position generates Spleen Earth at the Right Guan position; Spleen Earth generates Lung Metal at the Right Cun position. Generating from below upwards constitutes Pre-heaven Yuan Qi. As for Fire generating Earth, and Earth governing the generation of Water, circulating from above downwards, this constitutes Post-heaven Yuan Qi. Pre-heaven Yuan Qi initiates the generation of the Five Elements from formless Qi; Post-heaven Yuan Qi, starting from the formed Five Elements, circulates to nourish the Pre-heaven. Formless Yin and Yang Qi, through the virtue of Yin-Yang union, generate the spirit of Hun, Po, Shen, Zhi, and Yi, thereby producing emotions such as Joy, Anger, Worry, Thought, Grief, Fear, and Fright. These are the true Seven Emotions of nature. If they reach extremes, they will conversely damage the Pre-heaven Yin and Yang Qi.
How can we distinguish the Post-heaven Yin and Yang Qi of form? At the beginning of conception, one receives the Grain Qi (Gu Qi) from the mother's Spleen and Stomach to nourish the physical form. Thus, the Grain Qi of the Spleen and Stomach actually originates from the Pre-heaven formless Yin and Yang, further transforming into the Post-heaven formed Qi and Blood. If injured by improper diet or overexertion, the Post-heaven Yin and Yang Qi are damaged, leading to insufficiency of True Yin and Original Yang in the Kidney and Mingmen. This naturally fails to establish the Heavenly Origin for the Qi and Blood of the Twelve Meridians. If the Grain Spirit of the Spleen and Stomach is not充盈 (full), it cannot further sustain the True Yin and Original Yang of the Kidney and Mingmen to continue the life pulse. This explains the difference in the density and thinness of Pre- and Post-heaven Qi. If Pre-heaven Yuan Yin is injured, the spirit becomes mostly confused; at night, there is much restlessness. Just before sleep, there is fright and insomnia; after falling asleep, one fears people and feels uneasy, with palpitations and jumping, and the Hun and Shen are agitated. This is due to the movement of formless Fire within the thoughts and spirit. Treatment should involve greatly tonifying True Yin and simultaneously calming the Spirit, so that Fire descends naturally and the Spirit clears. However, if the Pre-heaven formless Yuan Yin Qi is insufficient, one must absolutely avoid using Ginseng Radix (Renshen), Atractylodis Rhizoma (Baizhu), and Astragali Radix (Huangqi). Only formulas like Dihuang Wan (Rehmannia Pill) that tonify True Yin and True Yang can fill this deficiency. Generally, Sweet-Warm herbs only tonify the Yang Qi of the Five Zang organs, whereas Sweet-Cold herbs tonify the True Yin of the Five Zang organs. However, if taking Yin-tonifying herbs does not lead to recovery, it is because the efficacy has not yet reached its peak and the deficiency has not yet returned. Without a large number of doses and long-term treatment spanning months or years, the condition cannot be reversed. Nevertheless, this is verified only when the patient feels Fire moving and unrest without taking medicine.
The Yin of the Pre-heaven formless Yuan Qi is the Mother Qi of my Kidney Water, inheriting the Ancestral Qi of Yuan Jing. Its substantive body of True Yin is deeply hidden within the Left Kidney; its miraculous function of True Yin operates silently within the Jing and Shen. Hence, it is said to be formless. If its True Yin is injured, it causes mental confusion, restless sleep at night, dry and uncomfortable eyes, aversion to light and sun, or dislike of people and fire, preference for stillness and fear of movement, and all things liked or seen are Yin-natured. This results from parents' excessive sexual desire, which inherently damages Kidney Qi, or occasional damage to True Yin during intercourse due to the Seven Emotions. Later in life, if one fails to moderate sexual desire and emotional fluctuations, causing combined damage since birth, how can one avoid vanity and disease? The treatment method should be gentle internal nourishment, preserving the remaining damaged Yin, tonifying Yin and Yang, and assisting their growth power. However, Yang Fire is easy to rescue, while Yin Water is hard to obtain. Therefore, insufficiency of Pre-heaven Yuan Yin True Water cannot be turned around unless calculated by time and effort. A single spark can respond to fires in mountains covering ten thousand qing; a cup of water is difficult to extinguish the fire of a cartload of firewood.