Chapter 5: Interaction of Yin-Yang and the Philosophy of Procreation

Section 1: Pre-Qin Philosophy of Procreation

The system of "Frost descends, women are wed; ice thaws, cessation kills; once in ten days, an embrace" is underpinned by a profound Pre-Qin philosophy of procreation, sometimes called the "Study of Seed" (zhongzi zhi xue 种子之学).

Pre-Qin people placed great importance on producing superior offspring. This was not merely a personal desire but a major concern for the ancestral temples and the state.

The Zuo Zhuan, Duke Zhao the 1st Year, records the words of the physician He when discussing an illness:

"The music of the former kings serves to moderate all affairs. Thus, there are Five Moderations. Slowness and quickness follow one another in sequence, with the central tone descending. After five descents, the string cannot be plucked further. At this point, there is a flurry of hand movements and lascivious sounds, which confuse the heart and ears, leading to forgetfulness of harmony. The noble man does not listen to it. Things are the same. When action reaches excess, then one stops. If one does not avoid this, illness will arise."

And further:

"Woman is a Yang thing, yet her time is dark. Indulgence leads to internal heat and the illness of entanglement. Now the lord does not moderate or time his actions; how can this not happen to him$3"

This passage describes Duke Jin’s illness, which Physician He diagnosed as resulting from "not moderating or timing" (bù jié bù shí)—immoderate and untimely conjugal visits. "Woman is a Yang thing, yet her time is dark; indulgence leads to internal heat and the illness of entanglement." This means that sexual relations with women, a Yang entity, at a dark time (i.e., excessively or out of season), cause internal heat and entanglement sickness.

Physician He’s words reveal the close relationship between Pre-Qin medicine and the regulations for conjugal visits. Visits must be moderated (jié 节) and timely (shí 时); otherwise, they harm the body, and the resulting children will be imperfect. This is the profound reason behind the warning in "Three days before the thunder is to sound, the wooden mud-drum is shaken," stating that if one fails to "restrain their appearance and repose," then "the birth of sons will not be complete, and there will surely be disaster."

The Zuo Zhuan, Duke Zhao the 1st Year, also records Physician He's discourse:

"Heaven has Six Qis (airs), which descend to produce the Five Flavors, manifest as the Five Colors, resonate as the Five Tones, and excess leads to the Six Diseases. The Six Qis are Yin, Yang, Wind, Rain, Obscurity, and Light. They are divided into Four Seasons, sequenced into Five Transitions; excess leads to disaster. Excess of Yin causes cold illnesses; excess of Yang causes heat illnesses; excess of Wind causes extremity illnesses; excess of Rain causes abdominal illnesses; excess of Obscurity causes confusion illnesses; excess of Light causes heart illnesses. Woman is a Yang thing, yet her time is dark; indulgence leads to internal heat and the illness of entanglement."

This passage corresponds the Six Qis of Heaven and Earth to human illnesses. "Excess of Obscurity causes confusion illness"—excessive lack of timing (indulgence) belongs to the excess of "Obscurity" (performing dark acts at the wrong time), thus causing "internal heat and entanglement sickness."

It can be seen that the moderation standard for conjugal visits in Pre-Qin times was not only concerned with health preservation but also with eugenics. Visits conforming to the season and timing guarantee that the offspring are physically sound and well-endowed; visits that violate timing and season lead to "incomplete" children and harm the parents' health.

Section 2: The Concern over "Incomplete Sons"

The Book of Rites, "Monthly Ordinances," for the second month of spring states:

"Three days before the thunder is to sound, the wooden mud-drum is shaken to announce in the thoroughfares, saying: 'The thunder is about to sound! Whoever does not restrain their appearance and repose will suffer calamity in the birth of their sons.'" (Liji 礼记·月令)

This passage is extremely significant. "Failing to restrain their appearance and repose" (wú jiè qí róng zhǐ) means failing to be vigilant and moderate one's behavior. "The birth of sons will not be complete" (shēng zǐ bù bèi) means the resulting children will be defective or flawed. "There will surely be disaster" (bì yǒu xiōng zāi).

Why would failure to restrain oneself when "thunder is about to sound" lead to "incomplete sons"$4

Pre-Qin people had a profound understanding of this. Thunder is the extreme manifestation of the surge of Yang qi. In the month of mid-spring, Yang qi rises from the earth, and the accumulated Yang energy suddenly erupts as thunder. At this time, the Yin and Yang of Heaven and Earth clash, and the flow of qi is chaotic.

If conjugal visits occur during this clash of Yin and Yang, the jing qi (essence and qi) of the couple will also become chaotic, following the surging Heavenly qi. Chaotic jing qi leads to a chaotic conception, resulting in "incomplete sons."

This principle, although derived from Pre-Qin Yin-Yang theory rather than modern science, finds some correspondence in modern medicine, which recognizes that factors like climate change and electromagnetic environments do affect human reproductive functions. While Pre-Qin people lacked modern scientific tools, they grasped this relationship through long-term accumulation of experience and acute observation.

"There will surely be disaster" implies not only "incomplete sons" but perhaps also harm to the parents. As quoted earlier from Physician He, "Indulgence leads to internal heat and entanglement sickness," meaning untimely visits harm the parents' bodies.

Thus, "Frost descends, women are wed; ice thaws, cessation kills" is not only a societal regulation regarding the marriage season but also a design for eugenics: by marrying and engaging in marital intimacy between Frost's Descent and the Thawing of Ice, one avoids the time of thunderous activity in mid-spring, maximizing the chance that the resulting children will be "complete" rather than "incomplete."

Section 3: Heavenly Essence and the Relationship to Conception

Pre-Qin thinkers believed that conception depended not only on the union of male and female essence but also on the cooperation of Heavenly and Earthly essence.

The Guanzi, "Inner Cultivation," states:

"When a person is born, Heaven produces his essence, and Earth produces his form; these combine to form the human." (Guanzi 管子·内业)

Heavenly essence (tiān zhī jīng 天之精) is the Yang qi, the celestial qi, the spiritual endowment. Earthly form (dì zhī xíng 地之形) is the Yin substance, the material endowment. The combination of Heavenly essence and Earthly form creates a complete human being.

At the time of conception through conjugal visits, if the Heavenly and Earthly essences are in a state of harmony (like the concealment in autumn and winter), the Heavenly essence and Earthly form can easily combine, resulting in offspring with superior endowments. If the Heavenly and Earthly essences are in a state of chaos (like the struggle in mid-spring), the Heavenly essence and Earthly form cannot combine harmoniously, and the resulting child may have defects.

The Guanzi, "Inner Cultivation," further elaborates:

"Essence is the quintessence of qi; the flow of qi leads to birth. Birth leads to thought, thought leads to knowledge, and knowledge leads to rest."

Essence is the purest form of qi. The transformation and generation of essence depend on the "flow of qi" (qì dào 气道)—the smooth operation of qi. When the qi of Heaven and Earth flows smoothly (during the stable convergence of autumn and winter), human jing qi also converges smoothly; this is the optimal time for conception. When the qi of Heaven and Earth is turbulent (during the struggle in mid-spring), human jing qi scatters; conception is then unsuitable.

The Guanzi, "Water and Earth," discusses the relationship between Water and reproduction even further:

"Man is Water. The essences and qi of men and women combine, and form flows like Water."

Human nature is Water; the combination of male and female essence is like the flow of water taking shape. Winter corresponds to Water, the time when Water is vigorous and essence is abundant—the most suitable time for conception. This aligns with the regulation of "Frost descends, women are wed."

Section 4: The System of Pre-Qin Eugenics

Synthesizing the above discussions, the Pre-Qin eugenics philosophy can be summarized as follows:

I. Harmony of Time (Hé Shí 合时)

Marriage and conjugal visits must occur in the appropriate season: autumn and winter are suitable; spring and summer are not. Specifically, between Frost's Descent and the Thawing of Ice.

II. Harmony of Regulation (Hé Jié 合节)

The frequency of visits must have appropriate moderation: based on age, status, and season, a rational frequency must be determined. "Once in ten days, an embrace" is one such standard.

III. Harmony with Rites (Hé Lǐ 合礼)

Marriage must follow the Six Rites: Nà cǎi, Wèn míng, Nà jí, Nà zhēng, Qǐng qí, Qīn yíng (纳采、问名、纳吉、纳征、请期、亲迎). The completeness of the rites is not only a requirement of social norms but was also believed to affect the resulting offspring. Those who marry according to rites will have children who also know rites; those who unite without rites (like "eloping couples") might have flawed offspring.

The Book of Rites, "The Meaning of Wedding" (昏义), states:

"The wedding rite is to unite the harmony between two clans, above to serve the ancestral temples, and below to continue the later generations. Thus, the noble man esteems it."

The solemnity of the wedding ceremony lies in its connection to "continuing the later generations," which means not just producing descendants but producing superior descendants to perpetuate the clan’s bloodline and spirit.

IV. Harmony of Virtue (Hé Dé 合德)

The union of husband and wife should occur when both are in a good physical and spiritual state.

The Book of Rites, "Inner Regulations," states:

"When one is about to embrace the ruler, she cleanses herself, bathes, and dresses." (Liji 礼记·内则)

"Qí" (齐) means fasting or purification. Before a visit, one must fast and bathe, purifying the body and mind. This is not merely for cleanliness but for the concentration of spirit. When visiting in a state of purification, the spirit is focused, and qi is concentrated, making the resulting child ideally endowed.

This requirement of "Harmony of Virtue" is the essence of Pre-Qin eugenic thought. It posits that the physical and mental state of the parents at the time of conception directly influences the quality of the offspring. This idea finds some echoes in modern genetics and epigenetics.

V. Harmony of Number (Hé Shù 合数)

The "ten days" in "Once in ten days, an embrace" is not an arbitrary number but accords with the number of the Heavenly Dao. As discussed earlier, it relates to the Heavenly Stems and the xún cycle. Furthermore, "ten" carries the meaning of "completion" in Pre-Qin numerology.

The Book of Documents, "The Great Plan," states:

"Heaven produces Water as One; Earth produces Fire as Two; Heaven produces Wood as Three; Earth produces Metal as Four; Heaven produces Earth as Five. Heaven's numbers are five, Earth’s numbers are five; they combine in their respective series. Heaven's total number is twenty-five; Earth's total number is thirty. The total number of Heaven and Earth is fifty-five. This is how transformation is completed and the spirits and deities move."

This passage, found in the Yijing but related to the Hongfan, suggests that the combination of Heaven’s numbers (1, 3, 5, 7, 9) and Earth’s numbers (2, 4, 6, 8, 10) totals ten. Ten represents the complete cycle of Heaven and Earth’s numbers. "Once in ten days, an embrace" uses the complete cycle of Heaven and Earth as its period, ensuring that each embrace receives the totality of the essence of Heaven and Earth, resulting in the most complete endowment.