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。
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.