天癸先天生身气，精血后天化成形。男子二八天癸至，属阳应日精日盈；女子二七天癸至，属阴应月
血月通。男女媾精乃有子，干道男成坤女成。
【注】天癸乃父母所赋，先天生身之真气也。精血水谷所化，后天成形之本也。男子
二八，先天肾气盛，天癸至，与后天所生之精会合而盈然。男子属阳，阳应日，故精盈
而日举也。女子二七，先天气实，天癸至，与后天所生之血会合而盛然。女子属阴，阴
应月，故血盛而月下也。所以至期男女媾，其先天真气，后天精血，阴阳会和，乃能有子
也。当此阴阳会合时，阳盛自然成男，是干道成男也。阴盛自然成女，是坤道自然成女
也。
精通必待三十娶，天癸二十始适人，皆欲阴阳完实后，育子坚壮寿偏增。
【注】男子十六而精通，必待三十而娶，女子十四而天癸至，必待二十而嫁者，皆欲
阴阳完实。然后交而孕，孕而育，育而其子必坚壮长寿也，今未笄之女，天癸始至，已
近男色，则阴气早泻，未完而伤，未实而动，所以虽交而不孕，孕而不育，育而其子必脆
弱不寿也。
男子聚精在寡欲，交接乘时不可失，须待 时候至，乐育难忍是真机。
【注】聚精之道，惟在寡欲，交接女子，
必乘其时，不可失之迟早。盖妇人一月经行一度之后，必有一日 蕴之时，气蒸而热，如
醉如痴，有欲交接不可忍之状，乃天然节候，是成胎生化之真机也。
天癸源于先天，由生身之气化生；精血源于后天，由水谷精微化成形体。男子到了十六岁（二八），天癸到来，属于阳，对应日精而日益充盈；女子到了十四岁（二七），天癸到来，属于阴，对应月信而每月通畅。男女交合精气，于是有了子女，遵循天道男性成形，遵循地道女性成形。
【注】天癸是父母赋予的，是构成生命本源的先天真气。精血由水谷转化而来，是后天形成形体的根本。男子十六岁时，先天肾气旺盛，天癸至，与后天所生的精液会合而充盈。男子属阳，阳对应日，所以精液充盈且每日勃起。女子十四岁时，先天之气充实，天癸至，与后天所生的血液会合而盛满。女子属阴，阴对应月，所以血液盛满而月经来潮。因此到了适婚年龄男女交合，其先天真气与后天精血，阴阳调和，于是能够生育子女。在此阴阳会合之时，阳气盛自然生成男孩，这是天道成男。阴气盛自然生成女孩，这是地道成女。
精通必待三十岁娶妻，天癸初至二十岁始嫁人，都是想要阴阳完全充实之后，生育的孩子坚固强壮且寿命延长。
【注】男子十六岁精通，但必须等到三十岁才娶妻，女子十四岁天癸至，但必须等到二十岁才出嫁，都是为了等待阴阳完全充实。然后交合才能受孕，受孕才能孕育，养育的孩子必然坚固长寿。如今未行笄礼的女子，天癸刚刚来到，就接近男子，那么阴气过早泄露，身体未充实而受损，未成熟而妄动，所以虽然交合也不能怀孕，即使怀孕也不能养胎，即使生下孩子也必然脆弱短寿。
男子聚精在于减少欲望，性交要乘时机不可错失，须等待女方排卵期至，情欲难忍才是受孕的真机。
【注】聚精的方法，只在减少欲望，与女子交接，必须趁着她的适宜时期，不可过早或过晚。大概妇女一个月经行一次之后，必有一天处于蕴育之时，体内气蒸发热，像喝醉又像发痴，有想要交合难以忍受的状态，这是天然的节候，是成胎生化的真机。
Tian Gui (Heavenly Water) originates from congenital essence and is generated by the vital Qi of life; Jing Xue (Essence and Blood) originates from acquired nature and is formed from the transformation of Gu Qi (Grain Qi). At the age of sixteen (2x8), Tian Gui arrives in males; belonging to Yang, it corresponds to the Sun's essence and becomes increasingly abundant. At the age of fourteen (2x7), Tian Gui arrives in females; belonging to Yin, it corresponds to the Moon's blood and flows monthly. When male and female combine their essence, offspring are conceived, following the Dao of Heaven for males and the Dao of Earth for females.
[Note] Tian Gui is endowed by parents and is the congenital True Qi that constitutes life. Essence and Blood are transformed from food and water and serve as the foundation for forming the physical body in acquired nature. At sixteen, a male's congenital Kidney Qi is vigorous; Tian Gui arrives and merges with the essence produced in acquired nature, becoming abundant. Males belong to Yang, and Yang corresponds to the Sun; thus, essence is abundant and erections occur daily. At fourteen, a female's congenital Qi is substantial; Tian Gui arrives and merges with the blood produced in acquired nature, becoming full. Females belong to Yin, and Yin corresponds to the Moon; thus, blood is full and menstruation occurs. Therefore, when men and women unite at the appropriate age, their congenital True Qi and acquired Essence and Blood harmonize in Yin and Yang, enabling conception. During this union of Yin and Yang, an abundance of Yang naturally results in a male, which is the Dao of Heaven creating males. An abundance of Yin naturally results in a female, which is the Dao of Earth creating females.
One should wait until thirty to marry after achieving seminal emission, and wait until twenty to marry after the onset of menstruation, all to ensure that Yin and Yang are fully matured, so that the offspring born will be robust, strong, and long-lived.
[Note] A male achieves seminal emission at sixteen but must wait until thirty to marry; a female experiences the onset of menstruation at fourteen but must wait until twenty to marry. This is done to allow Yin and Yang to become fully complete and solid. Only then can intercourse lead to pregnancy, pregnancy to gestation, and the child born will be sturdy and long-lived. Nowadays, girls who have not yet undergone the capping ceremony (Ji Li) may approach men as soon as Tian Gui begins. This causes Yin Qi to leak prematurely, damaging the body before it is complete and stirring movement before it is solid. Consequently, although intercourse may occur, conception fails; if conception occurs, gestation fails; and if birth occurs, the child is inevitably fragile and short-lived.
For males, accumulating essence requires reducing desires. Intercourse must be timed correctly and not missed. One must wait for the fertile window to arrive; the unbearable intensity of sexual desire marks the true mechanism for conception.
[Note] The method of accumulating essence lies solely in reducing desires. When engaging in intercourse with a woman, one must seize the opportune time and not be too early or too late. Generally, after a woman's menstrual flow ends once per month, there is a day of "Yun" (gestation/ovulation). During this time, internal Qi steams and generates heat; she appears intoxicated and infatuated, experiencing an unbearable urge to engage in intercourse. This is a natural seasonal rhythm and the true mechanism for conception and biological generation.