谁识雌雄在坎离，玄关消息有真机。坎虚离实云非是，坎实离虚亦是非。天以至刚方得
体，地缘无日乃成泥。三生同有金丹在，试问仙翁知不知？
种子之法，古人言之不少，而余谓其若未尽善者，盖亦有疑而云然。谨并列而辨之，亦
以备达者之裁正。
一、《广嗣诀》云∶三十时辰两日半，二十八九君须算，落红满地是佳期，金水过时徒
霍乱，霍乱之时枉费功，树头树底觅残红，但解开花能结子，何愁丹桂不成丛。按∶此言妇
人经期方止，其时子宫正开，便是布种之时，过此佳期，则子宫闭而不受胎矣。然有十日半
月及二十日之后受胎者，又何为其然也。又一哲妇曰∶若根据此说，则凡有不端者，便于后半
月为之，自可无他虑矣。善哉言也，此言果可信否？
一、《道藏经》曰∶妇人月信止后一日、三日、五日合者，干道成男；二日、四日、六
日合者，坤道成女。按∶此以单数属阳，故成男；偶数属阴，故成女。果若然，则谁不知之
，得子何难也？总未必然。
一、《褚氏遗书》云∶男女之合，二情交畅。若阴血先至，阳精后冲，血开裹精，精入
为骨而男形成矣；阳精先至，阴血后参，精开裹血，血入为本而女形成矣。按此一说，余初
见之，甚若有味有理，及久察之，则大有不然。盖相合之顷，岂堪动血，惟既结之后，则精
以肇基，血以滋育而胎渐成也。即或以血字改为精字，曰阴精先至，似无不可。然常见初笄
女子，有一合而即孕者，彼于此时，畏避无暇，何云精泄？但其情动则气至，气至则阴辟，
阴辟则吸受，吸受则无不成孕，此自然之正理也。若褚氏之说，似穿凿矣。
一、东垣曰∶经水断后一二日，血海始净，精胜其血，感者成男；四五日后，血脉已旺
，精不胜血，感者成女。按∶此说亦非确论。今见多生女者，每加功于月经初净而必不免于
女者，岂亦其血胜而然乎。
一、丹溪曰∶阴阳交构，胎孕乃凝，所藏之处，名曰子宫，一系在下，上有两岐，中分
为二，形如合钵，一达于左，一达于右。精胜其血，则阳为之主，受气于左子宫而男形成；
精不胜血，则阴为之主，受气于右子宫而女形成。按∶此乃与《圣济经》左动成男，右动成
女之说同。第以子粒验之，无不皆有两瓣，故在男子亦有二丸，而子宫之义谅亦如此，信非
谬也。惟左受成男、右受成女之说，则成非事后莫测其然。即复有左射右射之法，第恐阴中
阖辟，自有其机，即欲左未必左，欲右未必右。而阴阳相胜之理，则在天时人事之间，似仍
别有一道，虽知此说，终无益也。
谁能识得坎（肾，属水）与离（心，属火）之间的雌雄奥秘，玄关（人体精气神汇聚的关键窍穴）中的生机消息蕴含着真正的玄机。说“坎虚离实”是不对的，说“坎实离虚”也是不对的。天因为至刚才能确立其形体，地如果没有太阳日照就会变成泥土。（天地人）三生之中都蕴藏着金丹（内丹修炼的成果），试问那些仙翁们是否知晓？
关于生育后代的法则，古人论述不少，但我认为其中有些尚未尽善尽美，因此带着疑问进行阐述。谨此并列加以辨析，以备通达之士裁断指正。
一、《广嗣诀》说：“三十个时辰加上两天半，共计二十八九日，您必须算清楚。当经血停止、满地落红之时是受孕的好时机；如果过了这个‘金水’（指月经期）时期，徒劳无功只会造成混乱；在混乱之时枉费功夫，就像在树头树底寻找残存的花瓣一样。只要懂得开花就能结子，何必担心丹桂不成丛呢？”按：这是说妇女经期刚结束的时候，子宫正处于开放状态，正是播种（受孕）的时机；过了这个佳期，子宫闭合就不能受孕了。然而，有在半月或二十天之后才受孕的情况，这又是为什么呢？又有一位聪慧的女子说：“如果依据这种说法，那么凡是有不轨行为的人，只要在半个月后进行，自然就没有其他顾虑了。”这话真是妙啊，但这种话果真可信吗？
一、《道藏经》说：“妇女月信停止后的一日、三日、五日同房，会生男孩；二日、四日、六日同房，会生女孩。”按：这是以单数属于阳，所以生男；偶数属于阴，所以生女。如果真的这样，那谁不知道呢，得子岂不是很容易？总之未必如此。
一、《褚氏遗书》说：“男女交合，两情舒畅。如果阴血先到，阳精后冲，血液张开包裹精液，精液进入成为根本，男孩的形体就形成了；如果阳精先到，阴血后参入，精液张开包裹血液，血液进入成为根本，女孩的形体就形成了。”按：对于这一说法，我起初觉得很有味道、很有道理，但仔细考察久了，发现大有不妥之处。大概是在交合之际，哪里能触动出血来呢？只有在结合之后，精液作为基础，血液用来滋养，胎儿才逐渐形成。即使把“血”字改为“精”字，说“阴精先到”，似乎也没有不可。但是常见初成年女子，有一次交合就怀孕的，她们在那个时候，忙于避讳无暇顾及，怎么能说是精液先泄出呢？只是当情欲发动时，气随之而至，气至则阴户开启，阴户开启则吸收受纳，一旦吸收受纳就没有不怀孕的，这是自然的正理。至于褚氏的说法，似乎过于穿凿附会了。
一、李东垣说：“经水断后一二日，血海刚刚干净，精胜过了血，感应的就成男；四五日后，血脉已经旺盛，精胜不过血，感应的就成女。”按：这种说法也不是确切的定论。现在见到很多生女孩的，每次都在月经刚干净时努力同房，却必然免不了生女孩，难道也是因为血胜了吗？
一、朱丹溪说：“阴阳交合，胎孕乃凝结，所藏之处叫做子宫，有一系在下，上面分两岐，中间分为二，形状像合起来的钵，一支通向左边，一支通向右边。精胜过了血，则阳为主宰，在左子宫受气而男孩形成；精胜不过血，则阴为主宰，在右子宫受气而女孩形成。”按：这与《圣济经》中“左动成男，右动成女”的说法相同。只是从种子颗粒检验来看，无不都有两瓣，所以在男子也有两个睾丸，子宫的含义想必也是如此，相信并非谬误。唯独“左受成男、右受成女”的说法，则是事后无法推测其必然性。即使有向左射、向右射的方法，只恐怕阴道开合自有其机理，想要向左未必向左，想要向右未必向右。而阴阳相胜的道理，似乎在于天时人事之间，另有一条道路，虽然知道这种说法，终究没有益处。
Who can recognize the yin and yang (male and female principles) within Kan (Kidney, Water element) and Li (Heart, Fire element)? The vital mechanism of the Xuan Guan (Mysterious Pass, a key aperture for essence, qi, and spirit) holds the true secret. To say "Kan is empty and Li is solid" is incorrect; to say "Kan is solid and Li is empty" is also incorrect. Heaven establishes its form through utmost rigidity; Earth becomes mud without the sun's warmth. Within the triad of Heaven, Earth, and Humanity, the Golden Elixir (Jin Dan, the result of internal alchemy) exists in all; let us ask if the Immortals know this?
Regarding the methods for conceiving offspring, ancients have spoken extensively, yet I consider some aspects not entirely perfect, hence my doubts and explanations. Hereby, I list them for辨析 (analysis) and correction by those with profound understanding.
1. *Guang Si Jue* (Secrets for Progeny) states: "Thirty hours plus two and a half days, totaling twenty-eight or twenty-nine, you must calculate carefully. When menstrual blood stops and red petals fall everywhere, it is the auspicious time; passing the 'Jin Shui' (metaphor for menstruation) period leads to futile confusion. Wasting effort during confusion is like searching for residual flowers under trees. If one understands that blooming leads to fruiting, why worry about cassia not forming clusters?" Annotation: This implies that when a woman's menstruation just ends, the uterus is open, making it the time for sowing (conception). After this period, the uterus closes and cannot conceive. However, conception occurs after half a month or twenty days in some cases. Why is this so? Another wise woman remarked: "If we follow this theory, anyone acting improperly could simply wait until the second half of the cycle, avoiding any concerns." How excellent these words are! But are they truly credible?
2. *Dao Zang Jing* (Canon of the Dao) states: "Intercourse on the first, third, or fifth day after menstruation ceases results in a male child (Yang); intercourse on the second, fourth, or sixth day results in a female child (Yin)." Annotation: This attributes odd numbers to Yang (male) and even numbers to Yin (female). If this were true, everyone would know it, and having children would be easy. In reality, this is not necessarily the case.
3. *Chu Shi Yi Shu* (Remnant Book of Master Chu) states: "When man and woman unite, their emotions flow smoothly. If Yin Blood arrives first and Yang Essence follows, the blood opens to wrap the essence; the essence enters to become the foundation, forming a male. If Yang Essence arrives first and Yin Blood follows, the essence opens to wrap the blood; the blood enters to become the foundation, forming a female." Annotation: Initially, I found this reasoning appealing. However, upon closer examination, it seems flawed. During union, how can blood be moved? Only after conception does the essence lay the foundation and the blood nourish, gradually forming the fetus. Even if we change "blood" to "essence," saying "Yin Essence arrives first," it might seem plausible. Yet, it is common for young women to conceive from a single encounter. At that time, they are busy avoiding impropriety, so how can it be said that essence is discharged first? Rather, when desire stirs, Qi arrives; when Qi arrives, the Yin orifice opens; when the orifice opens, it absorbs; once absorbed, pregnancy invariably occurs. This is the natural law. Chu's theory seems forced and far-fetched.
4. Li Dongyuan stated: "One or two days after menstruation ends, the Sea of Blood is clean; Essence surpasses Blood, resulting in a male. Four or five days later, the blood vessels are vigorous; Blood surpasses Essence, resulting in a female." Annotation: This is not a definitive conclusion. Today, many couples who strive for conception immediately after menstruation still only have daughters. Is it because Blood prevails?
5. Zhu Danxi stated: "Through the union of Yin and Yang, the fetus condenses. The storage place is called the Uterus (Zi Gong), which hangs down and has two branches above, divided into two, shaped like a joined bowl, one reaching left and one right. If Essence surpasses Blood, Yang dominates, Qi is received in the left uterus, forming a male. If Essence does not surpass Blood, Yin dominates, Qi is received in the right uterus, forming a female." Annotation: This aligns with the *Sheng Ji Jing* (Holy Grace Canon) stating "Left movement forms male, right movement forms female." Examining seed grains, both have two lobes; thus, men have two testes, and the structure of the uterus is likely similar, so this is not erroneous. However, the idea that "left reception forms male, right reception forms female" cannot be predicted beforehand. Even with techniques for aiming left or right, the opening and closing of the vagina have their own mechanisms; wanting to aim left may not result in going left. The principle of Yin-Yang dominance seems to lie between heavenly timing and human affairs, following another path. Knowing this theory ultimately offers no benefit.