男子到了十六岁,天癸(促进性发育的精微物质)到来;女子到了十四岁,天癸也到来。如果过早进行性交,会损伤先天元气,这是导致早夭的原因;男子到了六十四岁,天癸枯竭;女子到了四十九岁,天癸也枯竭。此时精血不再产生,如果房事不加节制,就是自己缩短寿命。人身上的血液,贯通全身骨骼肢体,当性欲发动时,汇聚全身的血液,到达命门(肾间动气所在之处),转化为精液而泄出(人受胎时,都禀赋此命门之火以生成生命,所以庄子说:火,是传递的,不知道它的尽头)。精液,精神依靠它就像鱼依靠水一样(精神必须依附于物体,才有依托,所以关尹子说:精,没有固定的形体;神,没有自我意识。楞严经说:火的性质没有自我,寄托在各种因缘上)。气依靠精液就像雾气覆盖深渊一样。不知道节制吝啬,就会使全身经脉干枯萎缩,房事没有限度,必然损伤肾中元气。虽然外表没有射精,但精液已经离开宫室,必定有几滴真精,随着阳具疲软而溢出,就像火有……
When a male reaches sixteen years of age, Tian Gui (the subtle substance promoting sexual development) arrives; when a female reaches fourteen years of age, Tian Gui also arrives. If sexual intercourse occurs too early, it damages Yuan Qi (Primordial Qi), which is the cause of premature death. When a male reaches sixty-four years of age, Tian Gui ceases; when a female reaches forty-nine years of age, Tian Gui also ceases. At this stage, Jing and Xue (Essence and Blood) are no longer generated. If sexual activity is not restrained, one shortens their own lifespan. The blood in the human body penetrates all bones and limbs. When sexual desire arises, the blood from the entire body converges at Ming Men (the seat of Kidney Yang/Mingmen Fire), transforms into Jing (Essence), and is ejaculated. (When conception occurs, the fetus inherits this Ming Men Fire to generate life; thus, Zhuangzi said: "Fire is transmitted, its end unknown.") Jing (Essence) is relied upon by Shen (Spirit) as fish rely on water. (Shen must attach to an object to have a basis for existence; thus, Guanyin Zi said: "Jing has no fixed form; Shen has no self-awareness." The Shurangama Sutra states: "The nature of fire has no self, relying on various conditions.") Qi relies on Jing like mist covers an abyss. Failing to practice moderation and conservation will lead to the withering of all meridians. Unrestrained sexual intercourse inevitably damages the Kidney's Yuan Qi. Even if ejaculation does not occur externally, the Jing has already left its palace. A few drops of true Jing will inevitably overflow along with the flaccidity of the penis, similar to how fire has...