凡交会下种之时，古云宜择吉日良时，天德月德，及干支旺相，当避丙丁之说，顾以仓
猝之顷，亦安得择而后行，似属迂远，不足凭也。然惟天日睛明，光风霁月，时和气爽，及
情思清宁，精神闲裕之况，则随行随止，不待择而人人可办，于斯得子，非惟少疾，而必且
聪慧贤明，胎元禀赋，实基于此。至有不知避忌者，犯天地之晦冥，则受愚蠢迷蒙之气；犯
日月星辰之薄蚀，则受残缺刑克之气；犯雷霆风雨之惨暴，则受狠恶惊狂之气；犯不阴不阳
、倏热倏寒之变幻，则受奸险诡诈之气。故气盈则盈，乘之则多寿；气缩则缩，犯之则多夭
。顾人生六合之内，凡生长壮老已，何非受气于生成？而知愚贤不肖，又孰非禀质于天地？此
感兆元始之大本，苟思造命而赞化育，则当以此为首务。
干道成男，坤道成女，此固生成之至道，然亦何以见之，亦何以用之？盖乾坤不用，用
在坎离，坎离之用，阴阳而已。夫离本居阳，何以为女？以阳之中而阴之初也。坎本居阴，
何以为男？以阴之中而阳之初也。盖中者盛于上，盛者必渐消；初者生于下，生者必渐长。
故阳生于坎，从左而渐升，升则为阳而就明；阴生于离，从右而渐降，降则为阴而就晦，此
即阴阳之用也。而千变万化，莫不由之。由之推展，则凡冬至夏至，一岁之阴阳也；子东午
西，一日之阴阳也；有节有中，月令之阴阳也；或明或晦，时气之阴阳也；节前节后，消长
之阴阳也；月光潮汛，盈虚之阴阳也。再以及人，则老夫女妻，阴若胜矣，有颠之倒之之妙
；彼强此弱，阳亦在也，有操之纵之之权，顾无往而非阴阳之用也。知之而从阳避阴，则干
道成男；不知而背阳向阴，则坤道成女矣。明眼人其鉴而悟之，笔有难于尽意也。
凡是男女交合受孕的时候，古人说应当选择吉日良辰，如天德、月德等吉利时日，以及干支五行旺盛相生的时候，应当避开丙丁日（属火之日）。然而考虑到在情欲冲动之际，怎么可能先择日再行房事呢？这似乎显得迂腐遥远，不足以作为依据。但是，只有在天气晴朗明亮，风清月白，气候温和清爽，以及心情平静安宁、精神悠闲充裕的情况下，随时可以进行，不需要刻意挑选，人人都能做到。在这样的状态下受孕得到的孩子，不仅少生病，而且必定聪慧贤明，胎儿的先天禀赋，实际上就基于此。至于那些不知道避忌的人，如果触犯天地昏暗之时，就会受到愚笨迷蒙之气的影响；如果触犯日月星辰蚀亏之时，就会受到残缺刑克之气的影响；如果触犯雷霆风雨狂暴之时，就会受到狠恶惊狂之气的影响；如果触犯阴阳不协调、忽冷忽热的变幻之时，就会受到奸险诡诈之气的影响。所以，当天地之气充盈时受孕，顺应它则多长寿；当天地之气缩敛时受孕，触犯它则多夭折。况且人生于天地六合之内，凡是从生长到壮盛再到衰老死亡的过程，哪一样不是受气于自然生成？而人的聪明与愚笨、贤良与不肖，又有谁不是禀受于天地的资质呢？这是感应元始大道的根本，如果想要改造命运并辅助天地化育万物，就应当把这一点作为首要任务。
乾道成就男性，坤道成就女性，这固然是生成的最高道理，但又是如何体现的呢？又是如何运用的呢？大概乾坤本体并不直接作用，作用在于坎卦和离卦。坎离的作用，就是阴阳而已。离卦本属于阳，为什么代表女性？因为它是阳之中阴的初生阶段。坎卦本属于阴，为什么代表男性？因为它是阴之中阳的初生阶段。大概中间阶段是旺盛的，旺盛之后必然逐渐消退；初始阶段是萌发的，萌发之后必然逐渐增长。所以阳气生于坎卦，从左边逐渐上升，上升就变为阳而趋向光明；阴气生于离卦，从右边逐渐下降，下降就变为阴而趋向晦暗，这就是阴阳的作用。千变万化，没有不由此产生的。由此推展，冬至夏至，是一年的阴阳变化；子时东方午时西方，是一日的阴阳变化；有节气有中气，是月令的阴阳变化；有时明亮有时晦暗，是时气的阴阳变化；节气前节气后，是消长的阴阳变化；月光潮汐，是盈虚的阴阳变化。再推及到人，那么老夫少妻，阴气似乎占优势，却有颠倒奇妙的妙用；彼强此弱，阳气也在其中，有操纵放纵的权变，总之无处不是阴阳的作用。懂得顺应阳气而避开阴气，就能成就男性（乾道成男）；不懂得背离阳气而趋向阴气，就只能成就女性（坤道成女）。明眼人应当审视并领悟其中的道理，笔墨难以完全表达其意蕴。
When the time for sexual intercourse and conception arrives, ancient texts state that one should select auspicious days and favorable hours, such as those blessed by Tiande (Heavenly Virtue) and Yuede (Lunar Virtue), and when the Heavenly Stems and Earthly Branches are in a prosperous phase, while avoiding Bing-Ding days (days associated with Fire). However, considering the urgency of the moment, how can one possibly delay action to select a day? This seems pedantic and remote, and thus insufficient as a reliable basis. Nevertheless, only when the weather is clear and bright, the wind is gentle and the moon is serene, the climate is mild and refreshing, and the mind is tranquil and the spirit is leisurely, can intercourse be conducted at any time without needing to select a specific date, which is achievable by everyone. Conception under such conditions yields offspring who not only suffer fewer illnesses but are also destined to be intelligent, virtuous, and wise; the prenatal endowment of the fetus is fundamentally established here. Conversely, those who fail to observe these precautions may encounter the dimness of heaven and earth, thereby receiving qi of stupidity and confusion; they may encounter the eclipse of the sun, moon, or stars, thereby receiving qi of incompleteness and conflict; they may encounter the brutality of thunderstorms and rain, thereby receiving qi of ferocity and madness; they may encounter the fluctuations of unbalanced yin-yang and sudden shifts between heat and cold, thereby receiving qi of treachery and deceit. Therefore, when qi is abundant, conceiving during this time leads to longevity; when qi is contracted, offending this time leads to premature death. Since human life exists within the six directions of the universe, every stage from growth to maturity, old age, and death is derived from the qi of creation. Furthermore, whether one is wise or foolish, virtuous or unworthy, all stem from the constitution endowed by heaven and earth. This is the fundamental principle of sensing the origin of existence. If one wishes to shape destiny and assist in the creative process of nature, this must be the primary concern.
The Dao of Qian (Heaven) forms males, and the Dao of Kun (Earth) forms females; this is indeed the supreme principle of generation. However, how is this manifested, and how is it applied? Generally, Qian and Kun do not act directly; their function lies in Kan (Water) and Li (Fire). The function of Kan and Li is simply Yin and Yang. Li originally belongs to Yang, yet why does it represent females? Because it represents the initial emergence of Yin within Yang. Kan originally belongs to Yin, yet why does it represent males? Because it represents the initial emergence of Yang within Yin. The middle phase is vigorous, and what is vigorous must gradually decline; the initial phase is generative, and what is generative must gradually grow. Thus, Yang arises from Kan, ascending from the left, becoming Yang and moving toward brightness; Yin arises from Li, descending from the right, becoming Yin and moving toward darkness. This is the application of Yin and Yang. All transformations arise from this. Extending this logic: Winter Solstice and Summer Solstice represent the Yin-Yang of a year; Zi (East) and Wu (West) represent the Yin-Yang of a day; Jieqi (Solar Terms) and Zhongqi (Mid-terms) represent the Yin-Yang of monthly commands; clarity and darkness represent the Yin-Yang of seasonal Qi; before and after solar terms represent the Yin-Yang of waxing and waning; the phases of the moon and tides represent the Yin-Yang of fullness and emptiness. Applying this to humans: In a marriage between an older husband and younger wife, Yin may seem dominant, yet there is a subtle power of inversion; where one is strong and the other weak, Yang is still present, exercising control and flexibility. Ultimately, nowhere is there not the application of Yin and Yang. Understanding this allows one to follow Yang and avoid Yin, resulting in the formation of a male (Qian Dao Cheng Nan); failing to understand leads one to turn away from Yang and toward Yin, resulting in the formation of a female (Kun Dao Cheng Nu). Those with clear insight should reflect upon and comprehend this; words are insufficient to fully convey its meaning.