精者，滋于身者也；气者，运于身者也；神者，主宰一身者也。如耳目手足之能运者，气也，使之
因事而运者，神也；运之或健或倦者，精也。
耳乃精窍，目乃神窍，口鼻乃气窍。故耳之闭塞，精病可知；目之昏蒙，神病可知；口之吼喘，气
病可知。
元精，乃先天真精，非交媾之精。元气，乃虚无空气，非呼吸之气。元神，乃本来灵神，非思虑之神。
所谓元精、元气、元神，由未生出胎以前而具，俱先天也。所谓交媾之精、呼吸之气、思虑之神，乃既生
出胎之后而用，俱后天也。
人身精实则气充，气充则神旺，此相因而永其生者也。精虚则气竭，气竭则神逝，此相因而速其死者也。
孙思邈云∶怒甚偏伤气，思多太损神，神疲精渐敝，形弱病相萦。
太益曰∶存神可以固元气，令病不生。若终日挠混，则神驰于外，气散于内，营卫昏乱，众疾相攻矣。
又曰∶神能使耳目手足视听持行，气即随而运之，故宁神即养气保精也。人之身如国。神如君，君良则
国治；气如民，民聚则国强，精如财，财蓄则国富。
人身液化为血，血化为精，精化为髓。如饮食水谷入胃，由脾磨化成液，生血以充精。故必借谷
气以培后天之精，人乃得生也。
精者，神倚之如鱼倚水，盖鱼借水养，神借精滋也。又，精者，气托之如雾托渊，盖渊浅则雾薄，
精衰则气弱也。
后天之精，以至阴之液，本于各脏之生化，不过藏之于肾，原非独出于肾也。
无摇尔精，乃可长生。无摇者，守之固也。人肝精不固，目眩无光，肺精不固，皮肉消瘦；肾精不
固，神气减散；脾精不固，齿发衰白。疾病随生，死亡将至，哀哉。
心牵于事，火动于中；心火既动，真精必摇。
《参赞书》曰∶人至中年以后，阳气渐弱。觉阳事犹盛而常举，必慎而抑之，不可纵情过度。一度
不泄，一度火灭，一度火灭，一度添油。若不强制，则是膏火将残，更去其油。故《经》语云∶急守精
室勿妄泄，闭而宝之可长活。
凡房室之事，火随欲起，煽动精室，虽不泄而精渐离位，若将出而复忍之，则精停蓄，必化脓血成毒。
精，是滋养身体的物质；气，是推动身体运行的动力；神，是主宰全身的主宰。如耳目手足能够运动，这是气的功能；使它们因应事务而运动，这是神的功能；运动时或强健或疲倦，这是精的状态。
耳是精的窍道，目是神的窍道，口鼻是气的窍道。所以耳朵闭塞，可知是精有病；眼睛昏蒙，可知是神有病；口中吼喘，可知是气有病。
元精（先天真精），是先天本有的真精，并非性交时的精液。元气（虚无空气），是虚无中的自然之气，并非呼吸之气。元神（本来灵神），是本来的灵性之神，并非思虑产生的神。所谓元精、元气、元神，是在未出生胎前就已具备的，都属于先天范畴。所谓交媾之精、呼吸之气、思虑之神，是出生后使用的，都属于后天范畴。
人身精充足则气充盈，气充盈则神旺盛，这是相互依存从而延长寿命的因素。精虚亏则气竭绝，气竭绝则神消散，这是相互影响从而加速死亡的因素。
孙思邈说：大怒过度偏伤气，思虑过多太损神，神疲乏则精渐败坏，形体虚弱则疾病缠绕。
太益说：存养精神可以固护元气，使疾病不产生。如果整天纷扰混乱，则神驰散于外，气涣散于内，营卫（运行于脉内和脉外的气）昏乱，各种疾病就会相互攻击。
又说：神能使耳目手足视听行走，气随即随之运行，所以宁静心神即是养气保精。人的身体如同国家。神如同君主，君主贤良则国家治理好；气如同百姓，百姓聚集则国家强盛，精如同财富，财富积蓄则国家富裕。
人体的液化为血，血化为精，精化为髓。如饮食水谷进入胃中，由脾磨碎化成津液，生成血液以充养精。所以必须借助谷气来培补后天的精，人才能生存。
精，是神依附的对象，如同鱼依附水，因为鱼借水滋养，神借精滋润。另外，精，是气依托的对象，如同雾气依托深渊，因为渊浅则雾薄，精衰败则气弱。
后天的精，作为至阴的液体，根本在于各脏腑的生化作用，不过储藏于肾，原本并非只出于肾。
不要摇动你的精，才可以长生。不摇动，就是坚守牢固。人的肝精不固，则目眩无光；肺精不固，则皮肉消瘦；肾精不固，则神气减散；脾精不固，则齿发衰白。疾病随之产生，死亡将至，悲哀啊。
《参赞书》说：人到中年以后，阳气逐渐衰弱。觉得阳事仍然强盛而经常勃起，必须谨慎地抑制它，不可放纵情欲过度。一次不泄精，就是一次火灭，一次火灭，就是一次添油。如果不强制控制，就像膏火将尽，又去掉它的油。所以《经》语说：急守精室勿妄泄，闭藏而宝爱它可以长久活命。
Jing (Essence) is that which nourishes the body; Qi (Vital Energy) is that which moves the body; Shen (Spirit) is that which governs the whole body. The ability of the ears, eyes, hands, and feet to move is due to Qi; what causes them to move in response to affairs is Shen; whether this movement is vigorous or fatigued depends on Jing.
The ear is the aperture for Jing, the eye is the aperture for Shen, and the mouth and nose are apertures for Qi. Therefore, if the ears are blocked, one can know there is a disease of Jing; if the eyes are dim and hazy, one can know there is a disease of Shen; if there is roaring and panting from the mouth, one can know there is a disease of Qi.
Yuan Jing (Primordial Essence) is the true primordial essence, not the semen from sexual intercourse. Yuan Qi (Primordial Qi) is the void natural air, not the breath from respiration. Yuan Shen (Primordial Spirit) is the original spiritual spirit, not the spirit from cognitive thought.
What is called Yuan Jing, Yuan Qi, and Yuan Shen are present before birth while still in the womb; all belong to the category of Xiantian (Pre-heaven/Innate). What is called semen from intercourse, breath from respiration, and spirit from thought are used after birth; all belong to the category of Houtian (Post-heaven/Acquired).
When the body's Jing is substantial, Qi is abundant; when Qi is abundant, Shen is vigorous. This mutual dependence prolongs life. When Jing is deficient, Qi exhausts; when Qi exhausts, Shen departs. This mutual influence accelerates death.
Sun Simiao said: "Extreme anger injures Qi unilaterally; excessive thinking damages Shen greatly. With mental fatigue, Jing gradually deteriorates; with physical weakness, diseases entangle."
Tai Yi said: "Preserving Shen can consolidate Yuan Qi, preventing disease. If one is chaotic and disturbed all day, Shen scatters outward, and Qi dissipates inward, causing Ying and Wei (Defensive and Nutritive Qi) to become confused and disordered, allowing various diseases to attack each other."
He also said: "Shen enables the ears, eyes, hands, and feet to see, hear, hold, and walk; Qi follows to move them. Thus, calming Shen is equivalent to nourishing Qi and preserving Jing. The human body is like a state. Shen is like the ruler; if the ruler is virtuous, the state is well-governed. Qi is like the people; if the people gather, the state is strong. Jing is like wealth; if wealth is accumulated, the state is rich."
Body fluids transform into Blood (Xue), Blood transforms into Jing, and Jing transforms into Marrow (Sui). When food and drink enter the stomach, the Spleen grinds them to form fluids, generating Blood to nourish Jing. Therefore, one must rely on Gu Qi (Grain Qi) to cultivate acquired Jing, so that life may be sustained.
Jing is what Shen relies upon, like a fish relying on water; just as fish are nourished by water, Shen is nourished by Jing. Furthermore, Jing is what Qi relies upon, like mist relying on an abyss; just as a shallow abyss results in thin mist, depleted Jing results in weak Qi.
Acquired Jing, being the fluid of extreme Yin, originates from the metabolic functions of the Zang-Fu organs. It is merely stored in the Kidney but does not originate solely from the Kidney.
Do not agitate your Jing, and you can achieve longevity. Not agitating means guarding it firmly. If Liver Jing is not firm, the eyes will be dizzy and lack luster; if Lung Jing is not firm, skin and flesh will emaciate; if Kidney Jing is not firm, Shen and Qi will diminish and scatter; if Spleen Jing is not firm, teeth and hair will decay and turn white. Diseases will arise accordingly, and death will approach. Alas.
If the heart is tied down by affairs, Fire (Heat) stirs within. Once Heart Fire stirs, True Jing must be shaken.
The *Canzan Shu* (Book of Assistance) says: "After middle age, Yang Qi gradually weakens. One may feel that sexual function remains strong with frequent erections, but one must cautiously suppress it and not indulge excessively. Each time one does not ejaculate, it is like extinguishing fire once; each time fire is extinguished, oil is added. If one does not enforce control, it is like the lamp oil running out and then removing more oil. Thus, the Classics say: 'Hastily guard the chamber of Jing, do not leak wantonly; close and treasure it, and you can live long.'"
In all matters of sexual intercourse, Fire rises with desire, stirring the chamber of Jing. Even if ejaculation does not occur, Jing gradually leaves its proper position. If one holds back just as it is about to emerge, Jing stagnates and accumulates, inevitably transforming into pus and blood, becoming toxic.