天地者，形之大也；阴阳者，气之大也。性形与气相资而立，未始偏废。男女媾精，万
物化生，天地阴阳之形气寓焉。语七八之数，七，少阳也；八，少阴也，相感而流通。故女子
二七天癸至，男子二八精气盛，则阴阳交合而兆始故也。语九十之数，九，老阳也；十，老
阴也 相包而赋形。故阴穷于九，女能方之，则以阴阳相生而成终故也。元气孕毓，皆始于子。
自子推之，男左旋，积岁三十而至巳；女右旋，积岁二十而至巳。巳为正阳，阴实从之。自
巳怀任，男左旋十月而生于寅；女右旋十月而生于申。申为三阴，寅为三阳，而生育之时着矣。
其禀赋也，体有刚柔，脉有强弱，气有多寡，血有盛衰，皆一定而不可易也。以至分野异域，
则所产有多寡之宜。是故荆扬薄壤多女，雍冀浓壤多男。吉事有祥，则所梦各应其类∶熊罴为
男之祥，蛇虺为女之兆，是皆理之可推者也。至于胎化之法，有所谓转女为男者，亦皆理之
自然。如食牡鸡，取阳精之存于天者；带雄黄，取阳精之存于地者；操弓矢，藉斧斤，取刚物
之见于人事者。气类潜通，造化密移，必于三月形兆之先。盖方仪则未具，形气藉母神而变化，
阳可以阴，而动静之所以相感也。观夫螟蛉之化，又可知矣。物类且然，况于人乎？
天地，是形体中最大的存在；阴阳，是气中最大的范畴。人的性情、形体与气相互依存而确立，从未有过偏废的情况。男女交合精气，万物由此化生，天地的阴阳形气便蕴含其中。从数字七八来看，七属于少阳，八属于少阴，二者相互感应而流通。所以女子十四岁时天癸（指月经及生殖机能）来潮，男子十六岁时精气旺盛，这是阴阳交合而孕育生命的初始原因。从数字九十来看，九是老阳，十是老阴，二者相互包容而赋予形体。所以阴数穷尽于九，女性若能顺应此理，则是通过阴阳相生来完成生命终结的缘故。元气孕育胎体，都起始于子时（或子位）。从子位推演，男性向左旋转，累积岁月三十年到达巳位；女性向右旋转，累积岁月二十年到达巳位。巳位代表正阳，阴气实际上顺从它。从巳位开始怀妊，男性向左旋转十月而在寅位出生；女性向右旋转十月而在申位出生。申位代表三阴，寅位代表三阳，生育的时机便彰显出来了。一个人所禀受的先天素质，体质有刚强与柔和之分，脉象有强盛与微弱之别，气有多与少的差异，血有盛与衰的变化，这些都是固定且不可改变的。至于不同地域分野，则所产性别有多寡的适宜性。因此，荆州和扬州土壤薄瘠的地方多生女孩，雍州和冀州土壤肥沃的地方多生男孩。吉祥之事会有预兆，所做的梦各自对应相应的类别：梦见熊罴是生男的吉兆，梦见蛇虺是生女的征兆，这些都是道理可以推演的。至于胎儿转化的方法，有所谓“转女为男”的说法，也都是自然之理。例如食用公鸡肉，是取自然界中存在的阳气精华；佩戴雄黄，是取大地中存在的阳气精华；操持弓矢，借用斧头刀具，是取人事中刚硬物品的属性。气类之间暗中相通，造化微妙转移，必定在胎儿三月成形之前发生。因为此时胎儿的仪态尚未具备，形体和气借助母亲的神机而变化，阳可以转化为阴，这就是动静相互感应的原理。观察螟蛉（一种昆虫）被桑虫化为子的现象，就可以知道了。万物种类尚且如此，何况是人呢？
Heaven and Earth are the greatest of forms; Yin and Yang are the greatest of Qi (vital energy). Nature, form, and Qi rely on each other to establish existence, never neglecting one for the other. When male and female unite their essence, myriad things are transformed; the form and Qi of Heaven and Yin and Yang are contained within this process. Regarding the numbers seven and eight: seven belongs to Shaoyang (Lesser Yang); eight belongs to Shaoyin (Lesser Yin). They interact and circulate. Thus, when girls reach fourteen years of age, Tian Gui (menstrual fluid/reproductive capacity) arrives; when boys reach sixteen years of age, Jing Qi (essence and Qi) becomes abundant. This is the initial cause of Yin-Yang union and conception. Regarding the numbers nine and ten: nine represents Laoyang (Old Yang); ten represents Laoyin (Old Yin). They envelop each other to endow form. Therefore, Yin reaches its limit at nine; if women can align with this, it is through the mutual generation of Yin and Yang that life concludes. The gestation of Yuan Qi (Original Qi) begins at Zi (the first earthly branch/position).推算 from Zi: males rotate leftward, accumulating thirty years to reach Si; females rotate rightward, accumulating twenty years to reach Si. Si represents Zhengyang (True Yang), and Yin actually follows it. Conception begins at Si; males rotate leftward for ten months and are born at Yin; females rotate rightward for ten months and are born at Shen. Shen represents Sanyin (Three Yin), and Yin represents Sanyang (Three Yang), thus revealing the timing of birth. In terms of innate endowment, the body has rigidity or softness, the pulse has strength or weakness, Qi has abundance or scarcity, and Blood has excess or deficiency. These are fixed and unchangeable. As for different geographical regions, the proportion of births varies accordingly. Therefore, in Jingzhou and Yangzhou where the soil is thin, more girls are born; in Yongzhou and Jizhou where the soil is rich, more boys are born. Auspicious events have omens; dreams correspond to their respective categories: dreaming of bears and tigers is an omen for a boy; dreaming of snakes and vipers is an omen for a girl. These are principles that can be deduced. Regarding methods of fetal transformation, there is the so-called "turning a female fetus into a male," which is also natural law. For example, eating rooster meat takes the Yang essence existing in heaven; wearing Realgar takes the Yang essence existing in earth; handling bows and arrows, relying on axes and knives, takes the rigid objects seen in human affairs. Qi of similar categories secretly communicates, and Creation shifts subtly, necessarily before the third month when the fetal form is established. At this stage, the physical structure is not yet complete; form and Qi change by relying on the mother's spiritual mechanism. Yang can transform into Yin, which is why movement and stillness interact. Observing the transformation of silk moths (Mingling) into other insects, we can understand this. If it is so for other species, how much more so for humans?