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。
《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，金水过时从霍乱，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，但于后半月为之，自可无他虑
矣。善哉言也！此言果可信否？
《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。
《诸氏遗书》云∶“男女之合，二精交畅，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。
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，岂亦其血胜而然乎？
丹溪曰∶“阴阳交媾，胎孕乃凝。所藏之处，名曰子宫。一系在下，上有两歧，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。第以子宫验之，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。
谁能够识别雌雄的奥秘在于坎卦与离卦之间，玄关中的生机蕴含着真正的玄机。说“坎虚离实”是不对的，说“坎实离虚”也是不对的。天因为至刚才能保持其形体，地因为没有一日不是湿润（无日乃成泥）才能形成泥土。三生万物皆拥有金丹之道，试问那些仙翁们是否知晓呢？
关于孕育子嗣的方法，古人谈论得不少，但我认为其中有些还不够完善，这也是因为有疑惑才这样说的。然而我谨慎地将这些说法并列出来加以辨析，以便让通达之士进行裁断纠正。
《广嗣诀》说：“三十个时辰加上两天半，二十八九天您必须计算清楚，经血停止、满地落红是受孕的好时机，如果过了金水之期再去求子就像得了霍乱一样徒劳无功，在树头树底寻找残红也是白费力气。只要懂得开花就能结出果实，何必担心丹桂不成丛呢？”
按语：这是说妇女经期刚刚结束的时候，此时子宫正张开，正是播种受孕的时机；过了这个佳期，子宫就会闭合而不再受胎了。但是，有在十天、半月甚至二十天之后受孕的情况，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，只要在月经后半周期行事，自然就可以没有后顾之忧了。”这话真是好啊！但这种说法果真可信吗？
《道藏经》说：“妇女月信停止后，在第一日、第三日、第五日行房事的，会生出男孩（干道成男）；在第二日、第四日、第六日行房事的，会生出女孩（坤道成女）。”
按语：这是以单数属于阳所以生男，偶数属于阴所以生女为理论。如果真的如此，那谁不知道呢？得到儿子还有什么难的呢？总之未必是这样。
《诸氏遗书》说：“男女交合，两精通畅。如果是阴血先到，阳精后到，血液张开包裹住精子，精子进入成为骨骼的基础，男孩的形体就形成了；如果是阳精先到，阴血随后参与，精子张开包裹住血液，血液进入成为根本，女孩的形体就形成了。”
按语：这一种说法，我初看时觉得很有味道、很有道理，但仔细考察久了，发现大有不对劲的地方。因为在交合的瞬间，怎么能扰动血液呢？只有在已经结合之后，精子作为基础，血液作为滋养，胎儿才逐渐形成。即使把“血”字改为“精”字，说“阴精先到”，似乎也没有不可之处。然而常见刚成年（初笄）的女子，有一次交合就怀孕的，她们在这个时候忙于避讳无暇顾及，怎么能说是精液泄出呢？只是当情欲发动时气机随之而至，气机到了则阴户开启，阴户开启则吸收精气，吸收了就没有不怀孕的，这是自然的正理。至于褚氏的说法似乎有些穿凿附会了。
李东垣说：“经水断绝后的一两天，血海刚刚开始干净，精子胜过血液，感应的就会生男孩；四五天之后，血脉已经旺盛，精子胜不过血液，感应的就会生女孩。”
按语：这种说法也不是确切的结论。现在看到很多人生女孩的情况，往往在月经刚刚干净时努力求子，却必然生女孩，难道也是因为血液胜过精子吗？
朱丹溪说：“阴阳交媾，胎孕才会凝结。所藏纳的地方，名叫子宫。有一条系带在下端，上面有两个分支，中间分为两部分，形状像合起来的钵，一条通向左边，一条通向右边。如果精子胜过血液，则阳气为主宰，在左边的子宫受气，男孩的形体就形成了；如果精子胜不过血液，则阴气为主宰，在右边的子宫受气，女孩的形体就形成了。”
按语：这与《圣济经》中“左侧动则成男，右侧动则成女”的说法相同。只是从子宫来验证，无不都有两瓣，所以在男子也有两个睾丸。而子宫的含义，想必也是如此，确实不是谬误。只是关于左侧受孕成男、右侧受孕成女的说法，则是事后诸葛亮，无法测知其所以然。即使有向左射、向右射的方法，只怕阴户的开启闭合自有其机理，即使想向左未必能向左，想向右未必能向右，而阴阳相互制胜的道理，似乎仍然存在于天时和人事之间，好像另有门道。虽然知道这种说法，终究也没有益处。
Who can recognize that the essence of male and female lies within Kan (Water) and Li (Fire), where the true mechanism of life resides in the mysterious gate. To say "Kan is empty and Li is solid" is incorrect, and to say "Kan is solid and Li is empty" is also incorrect. Heaven maintains its form through utmost firmness, while Earth forms mud because it is never without moisture. All three existences possess the Golden Elixir; let us ask if the Immortals know this?
Regarding the methods for conceiving offspring, ancients have spoken extensively, yet I consider some of their views imperfect, arising from doubt. However, I carefully list these theories for辨析 (analysis) so that enlightened scholars may judge and correct them.
*Guangsi Jue* states: "Thirty hours plus two and a half days, you must calculate twenty-eight or twenty-nine days. When menstrual blood stops and falls like red petals, it is the auspicious time. If one waits until the 'Metal-Water' phase passes, efforts are as futile as treating cholera; searching for residual red under trees is wasted labor. If one understands that blooming flowers yield fruit, why worry that cassia will not grow in clusters?"
Commentary: This implies that immediately after menstruation ends, the uterus is open, making it the ideal time for conception. After this period, the uterus closes and cannot receive pregnancy. However, pregnancies occurring ten days, half a month, or even twenty days later contradict this. A wise woman remarked: "If this theory holds, those engaging in illicit relations could simply wait until the second half of the cycle to avoid consequences." While clever, is this truly credible?
The *Daozang Jing* states: "For women, intercourse on the 1st, 3rd, or 5th day after menstruation ceases results in a son (Yang path); intercourse on the 2nd, 4th, or 6th day results in a daughter (Yin path)."
Commentary: This attributes sons to odd numbers (Yang) and daughters to even numbers (Yin). If this were true, everyone would know it, and having a son would be easy. In reality, this is likely not the case.
*Zhushi Yishu* states: "When man and woman unite, their essences flow freely. If Yin Blood arrives first and Yang Essence follows, the blood opens to envelop the essence; the essence enters to form bone, resulting in a male fetus. If Yang Essence arrives first and Yin Blood follows, the essence opens to envelop the blood; the blood enters to form the root, resulting in a female fetus."
Commentary: At first glance, this seems plausible. However, upon closer inspection, it is flawed. How can intercourse disturb blood at the moment of union? Only after conception does the essence serve as the foundation and blood as nourishment for fetal development. Even if we replace 'blood' with 'essence' (Yin Essence arriving first), it remains problematic. Often, young women conceive after a single encounter; they are busy avoiding such situations, so how can they be described as releasing essence? Rather, when desire arises, Qi moves; when Qi moves, the Yin opens; when the Yin opens, it absorbs essence; absorption leads inevitably to pregnancy. This is natural law. Chu’s theory seems forced.
Li Dongyuan stated: "One or two days after menstruation ends, the Sea of Blood is just cleared; if Essence exceeds Blood, a male is conceived. Four or five days later, Blood vessels are vigorous; if Essence cannot exceed Blood, a female is conceived."
Commentary: This is not a definitive conclusion. Many couples who strive for conception immediately after menstruation still only have daughters. Is this due to Blood exceeding Essence?
Zhu Danxi stated: "When Yin and Yang intertwine, pregnancy condenses. The storage place is called the Uterus. It has a connection below and two branches above, divided into left and right, shaped like a joined bowl. One reaches the left, one to the right. If Essence exceeds Blood, Yang dominates; conception occurs in the left Uterus, forming a male. If Essence does not exceed Blood, Yin dominates; conception occurs in the right Uterus, forming a female."
Commentary: This aligns with the *Shengji Jing* saying "Left movement creates males, right movement creates females." Anatomically, the uterus indeed has two lobes, similar to the two testes in men. Thus, the concept of the uterus having two parts is not erroneous. However, the idea that left conception yields males and right yields females is speculative post-hoc reasoning. Even with techniques for aiming left or right, the opening and closing of the Yin have their own mechanisms; one cannot force conception to occur specifically on the left or right. The principle of Yin-Yang dominance seems to lie between heavenly timing and human circumstances, suggesting another way. Knowing this theory ultimately offers no practical benefit.