《天原發微》Vol. 15

Chapter 15, Section 6 of Tianyuan Fawei was compiled by Bao Yunlong (courtesy name Jingxiang) of Luzhai and collated by Fang Hui (courtesy name Wanli) of Xugu. This section primarily discusses the concept of "the Two Centers."

The numbers one through ten form the complete numerical system of heaven and earth, with five and six being the pivotal numbers between them. Five occupies the center of heaven as the sovereign number of generation, while six resides at earth's core as the sovereign number of completion. Five is called the number within Yang, positioned amidst the Yang numbers one, three, seven, and nine; six is termed the number within Yin, situated among the Yin numbers two, four, eight, and ten.

Examining the total numbers of heaven and earth: five times five makes twenty-five, five times six makes thirty, summing to fifty-five. Subtracting five—heaven's core number—leaves fifty, known as the "Great Expansion Number" (for divination). Subtracting six—earth's core number—yields forty-nine, called the "Yarrow Stalk Number" (for milfoil divination). These two central numbers operate between heaven and earth: aligning with their middle path brings auspiciousness, while excess or deficiency invites misfortune.

Shao Yong observed: The foundation of heaven and earth begins with "the center." Humans dwell at heaven-earth's center, while the heart resides at the body's center. The sun is most potent at noon, the moon most full on the fifteenth day—thus the noble person values seizing timely equilibrium.

The Taiji (Supreme Ultimate) differentiates into heaven and earth, transforms between them to generate humans, and concentrates within humans as the heart. Humans are heaven-earth's heart, and the human heart naturally contains a complete heaven-earth. When sages emerge to establish the central path, they anchor heaven-earth's core, guiding all under heaven toward the middle way. Only thus can they assist heaven-earth in nurturing all beings and harmonize with the Dao of heaven.

Therefore, heaven centers on noon, earth on midnight; Yang centers at sunrise (卯时), Yin at sunset (酉时). Heaven and earth never deviate from this principle of centrality. As the saying goes: The sun begins declining upon reaching noon, the moon wanes after becoming full—excess leads to deviation, hence the noble person's emphasis on timely centrality.

The Yizhuan states: Heaven-earth's numbers total fifty-five, the Great Expansion Number being fifty. Heaven's twenty-five is five times five; earth's thirty is six times five. The Small Expansion Number is ten (two fives), the Great Expansion Number fifty (ten fives). Dong Cheng remarked that all numerical principles ultimately return to five—the root of numbers. Whether three heavens and two earths or three Yang and two Yin, these intricate numerical patterns all converge upon five as their foundation.

This scripture primarily elucidates the profound significance of the numbers "five" and "six" within the cosmic order.

First, regarding the number "five": Both the Yin and Yang lines in divination originate from the generative number five. The Five Phases (Wood, Fire, Earth, Metal, Water) develop to their ultimate expression through the number nine, while the five blessings (longevity, wealth, health, virtue, and peaceful death) manifest through forty-five variations—all fundamentally rooted in five. Both the Hetu and Luoshu (ancient divinatory diagrams) recognize five as the numerical source. Thus Heaven and Earth operate through the Qi of Five Phases; humans embody the five constant virtues (benevolence, righteousness, propriety, wisdom, and faithfulness); the heavens feature five planets (Venus, Jupiter, Mercury, Mars, Saturn); the earth has five sacred mountains (Tai, Hua, etc.); music contains five tones (gong, shang, jue, zhi, yu); and colors display five hues (blue, red, yellow, white, black). Further manifestations include the five relationships (parent-child, ruler-minister, etc.), five rituals (auspicious, inauspicious, military, diplomatic, celebratory), five insignia patterns, five punishments, five flavors (sour, bitter, sweet, pungent, salty), five grains, and military organization in units of five. All converge upon five as Heaven-and-Earth's central number.

Concerning the number "six": The "Canon of Yao" records 366 days in a year, while the "Announcement of Kang" mentions five or six days forming a xun period. Hexagrams contain six lines, and the moon's phases change every five or six days: six days for the new moon, six for the first quarter, six for fullness, six for waning, and six for disappearance. From midnight to noon spans six Yang hours, while noon to midnight comprises six Yin hours. The interaction of five and six generates transformations: two sixes make twelve months; three sixes yield eighteen changes (divination process); four sixes create twenty-four solar terms; six sixes form a year's count. Humans possess six virtues (wisdom, benevolence, sagacity, righteousness, loyalty, harmony) and six practices (filial piety, friendship, harmony, kinship, responsibility, compassion); six arts (rites, music, archery, charioteering, calligraphy, mathematics); ritual vessels include six zun and six yi vessels; six dou and six bian containers; music has six pitch standards and six modes. The "Rites of Zhou" documents six canons and six ministries; the queen possesses six ceremonial robes; cuisine employs six grains and six sacrificial animals (ox, sheep, pig, dog, wild goose, fish) with six clear beverages; food varieties number 120, sauces fill 120 urns, and tripods appear in twelve forms—all demonstrating sixfold patterns.

Zhu Xi concluded: Heaven-and-Earth's cyclical movements use six as their fundamental rhythm. When six Yang periods culminate, a Yin period emerges to moderate; when six Yin periods peak, a Yang period arises to balance—thus preventing excess. Only through such rhythmic alternation do the four seasons form. The celestial axis divides Heaven and Earth, while the four seasons—augmented by the solar commencements of spring, summer, autumn, and winter—create eight nodal points constituting the annual cycle. Major rhythms appear in sixfold, twelvefold, twenty-fourfold, and seventy-twofold patterns; minor rhythms like day-night divisions and lunar phases all manifest twelve segments, with six remaining the operative principle in practical application.

The number sixty holds profound significance in the Book of Changes (Yijing). Thirty-six (the number of Great Yang) plus twenty-four (the number of Great Yin) equals sixty; similarly, thirty-two (Lesser Yin) plus twenty-eight (Lesser Yin) also sums to sixty. The combination of ten Heavenly Stems and twelve Earthly Branches forms the sexagenary cycle of sixty, as does the multiplication of five tones with twelve pitch standards. Scholar Shao Yong (Northern Song Dynasty Neo-Confucianist) observed: "Heavenly Stems culminate at six, Earthly Branches culminate at five."

The Yellow Emperor's Inner Canon (Huangdi Neijing) records how the Yellow Emperor commanded his minister Da Nao to create the sexagenary calendar by observing the Big Dipper's handle orientation to establish the Heavenly Stems and Earthly Branches. The ten Heavenly Stems (Jia, Yi, etc.) represent solar cycles, while the twelve Earthly Branches (Zi, Chou, etc.) represent lunar cycles—their pairing generates sixty combinations. This reveals a fundamental pattern: phenomena beginning with five culminate at six, while those beginning with six culminate at five. The ten Heavenly Stems (2×5) multiplied by twelve Earthly Branches (2×6) yield thirty. Yang numbers commence from thirty—hence thirty days form a month and thirty years constitute a generation in ancient timekeeping. Yin numbers commence from twelve—thus twelve two-hour periods make a day and twelve months complete a year. Multiplying months by thirty gives 360 days (lunar year), while multiplying days by twelve yields 4,320 two-hour periods (360×12). All these numerical progressions stem from the dynamic interplay between five and six.

The Song Dynasty esoteric text Qianxu proposes: Heaven's median number is five (5×5=25), Earth's median number is six (5×6=30), their sum fifty-five representing the totality of cosmic generation. Among generative numbers (1-5), five occupies Heaven's center preceding six; among formative numbers (6-10), six occupies Earth's center following five. This manifests as: one-five yields six (Water), two-five yields seven (Fire), three-five yields eight (Wood), four-five yields nine (Metal), five-five yields ten (Earth). Just as water has sources and tributaries, fire has major and minor flames, wood has roots and tips, metal contains ores and edges, while earth encompasses foundations and tombs—all governed by the five-six principle. Yang numbers quintuple to ten, yin numbers sextuple to twelve. Shao Yong employed these core numbers to construct his calendrical masterpiece Supreme Principles Governing the World (Huangji Jingshi), elucidating cosmic truths. Both Sima Guang and Shao Yong frequently deliberated these arcane numerical principles, their scholarship representing the purest essence of this wisdom.

Cosmic operations follow this pattern: small cycles transform by fives and sixes, while grand cycles revolve in sixties.

This describes an ancient system using hexagrams (from the sixty-four hexagrams) and celestial stems/earthly branches (symbols from the calendrical system) to calculate temporal cycles. Each month corresponds to five hexagrams, with each hexagram containing six lines (yao). Thus five times six yields thirty (representing yang numbers), while six times six yields thirty-six (representing yin numbers), combining to form the annual cycle of twelve months and 360 days.

Small cycles operate in six-day units, where sixty minor cycles precisely compensate for the solar year's fractional days to complete the 360-day count. When celestial movements follow six-based calculations, they always produce a six-day surplus distributed across six time periods. The six time periods following Zi hour (11 PM - 1 AM) mark ascending yang phases, while those following Wu hour (11 AM - 1 PM) mark declining yang phases.

Calculated via the sixty stem-branch combinations, these cycles manifest at multiple levels: six months form a minor cycle, six years an intermediate cycle, sixty years a major cycle, and 360 years a complete grand cycle. For instance, the sixty-year cycle corresponds to stem-branch years from Jiazi to Jiawu (thirty years constituting one generation), while the six-month cycle shows yang growth from Zi month to Wu month and decline from Wu to Zi. Six years complete the rotation of six climatic influences (liuqi), while sixty years complete the five elemental movements (wuyun).

Song dynasty scholar Cai Yuanding (Master Xishan) elaborated: Heaven's numbers revolve around five (wuxing), while earth's numbers center on six (liuqi). Heaven manifests dual aspects (yin-yang), making five's double ten (as 3+7 or 1+9); earth displays hardness-softness characteristics, making six's double twelve (as 4+8 or 2+10). The ten heavenly stems represent yin-yang aspects of the five phases, while twelve earthly branches represent hardness-softness qualities of six qi - ultimately different expressions of the same cosmic energy.

The five phases manifest celestially as meteorological phenomena: rain, shine, cold, warmth, and wind; terrestrially as material elements: water, fire, wood, metal, and earth. For example, celestial rain corresponds to earthly water, celestial shine to earthly fire. Water and fire represent qi's forms; rain and shine represent material manifestations - thus celestial and terrestrial energies intertransform. Two transformations (yin-yang) represent pure states, while three transformations (five phases) represent blended states.

The Zuo Commentary notes humanity's six emotions (fondness, aversion, joy, anger, sorrow, pleasure) originate from six qi. Humans receive life through natural qi of yin, yang, wind, rain, gloom, and brightness: yin corresponds to metal, wind to earth, rain to wood, gloom (darkness) to water, and brightness to fire. Specifically: fondness arises from yang qi, aversion from yin qi, pleasure from wind, anger from rain, and sorrow from gloom.

This scripture primarily explores the relationship between the Qi (vital energy) of heaven and earth and human nature, as well as how to harmonize Yin-Yang energies to achieve balance.

The text first explains that heaven and earth possess six fundamental Qi (referring to the six natural phenomena: Yin, Yang, wind, rain, darkness, and brightness), which generate five flavors. When humans consume these five flavors, they correspond to heaven's six Qi. Different emotional expressions manifest through different Qi: sorrow produces weeping, joy brings song and dance, delight leads to generosity, while anger incites conflict. Happiness stems from affection, whereas anger arises from aversion. Only by maintaining moderation in sorrow and joy can one align with the intrinsic nature of heaven and earth, thereby achieving longevity.

The analysis then turns to how human temperaments and endowments vary: some individuals are excessively rigid due to an overabundance of Yang Qi; others are overly pliant because of excessive Yin Qi. Some display violent and perverse tendencies—this represents the negative aspect of Yang Qi; others exhibit cunning and sinister traits—the negative manifestation of Yin Qi. Some possess harmonious dispositions that are easily guided, while others remain stubborn and difficult to teach. These differences all stem from variations in the Yin-Yang Qi each person receives. However, it's crucial to note that Yin and Yang Qi themselves are neither good nor evil—these diverse temperamental characteristics naturally emerge through the processes of distribution, combination, and transformation.

The text points out that heaven, earth, and humanity are all composed of the same fundamental Qi. When celestial cycles become abnormal, disasters occur; when earthly phenomena deviate, strange portents appear; when human hearts violate the Dao and De (Virtue/Power), chaos ensues. These anomalies can move heaven and earth to produce supernatural signs. So-called "ominous disasters" include floods and droughts, famines, unseasonable cold or heat, thunderstorms and hail, solar and lunar eclipses, comets and meteors among celestial phenomena, as well as insect plagues, landslides, and earthquakes. All these result from Yang Qi being suppressed and unable to ascend, Yin Qi obstructed and unable to flow, creating calamities through the stagnation of the six Qi.

Finally, the text emphasizes that transforming chaotic Qi into harmonious Qi depends fundamentally on the ruler attaining the state of "central harmony." This enables heaven and earth to maintain their proper positions. The discussion then employs the hexagram transformations from the Yijing (Book of Changes) to illustrate the patterns of Yin-Yang waxing and waning: beginning with the Gou hexagram (one Yin line emerging) in the fifth month, Yin Qi gradually increases until reaching its peak in the tenth month's Kun hexagram (six Yin lines). Then Yang Qi regenerates, forming the Fu hexagram (one Yang line returning). The cycle from Gou to Fu encompasses seven stages of transformation—this constitutes the fundamental principle of "returning in seven days" in Yijing philosophy.

This passage primarily discusses different interpretations of the phrase "return in seven days" (七日来复) from the Zhouyi (Book of Changes). Both orthodox Confucian doctrine and Zheng Xuan's (Zheng Sinong) citation of the Yiwei (Apocryphal Texts on the Changes) mention the "six days and seven parts" (六日七分) theory, which forms part of the complete "hexagram-qi" system (古人用六十四卦对应一年气候变化的体系) where the sixty-four hexagrams correspond to annual climatic changes. While Confucius's and Wang Bi's (Fushi) annotations are clear, the question remains whether Zheng Xuan's (Kangcheng) interpretation is reasonable.

The author argues that both interpretations are valid. The Yijing encompasses all phenomena, adapting to the Dao of Heaven without fixed interpretations. When explaining the sages' classics, one may adopt the orthodox Confucian view, understanding "seven days" as "seven months," or follow the hexagram-qi theory, correlating "six days and seven parts" with the degrees of the celestial sphere (古代天文学将天空分为365.25度). These two interpretations can coexist, leaving the judgment to later generations.

However, the author points out a flaw in Wang Bi's annotation regarding "the extinction of yang qi" (阳气绝灭)—yang qi may weaken but never truly vanishes. Additionally, Wang Shu's claim that the sun's movement through seven lunar lodges (古代天文学将黄道分为二十八宿) from the fifth to the eleventh month signifies the revival of yang qi is inaccurate. In reality, the sun moves one degree daily, meeting the moon once monthly, and traversing seven lodges corresponds to seven months—days cannot be conflated with months.

The distinction between "seven days" and "seven months" has been thoroughly addressed by earlier scholars. The author explains: beginning with the Bo hexagram (剥卦, the 23rd hexagram) in the tenth month, yang qi gradually declines; by the Gou (姤卦, 44th) to Kun (坤卦, 2nd) hexagrams, the six yang lines are exhausted. At the winter solstice (子半) in the eleventh month, yang qi begins to regenerate. If calculated based on yang qi, this is the "return in seven days" (where "seven days" actually means seven months); if based on yin qi, it is six months. This phrasing reflects the philosophical emphasis on honoring yang qi.

Lastly, three interpretations of the Fu hexagram (复卦, the 24th hexagram) are discussed: Zhou Dunyi (Lianxi) interprets it as a return to the Kun hexagram, emphasizing fu as a return to authenticity; Cheng Yi (Yichuan) focuses on "movement" (动), viewing it as the inception of heaven-and-earth's vitality; while Shao Yong (Kangjie) understands it as the state between movement and stillness. Zhu Xi (Master Zhu) considers these principles fundamentally identical, differing only in emphasis. Observing the lowest line (初九爻) of Fu, which indeed symbolizes movement, and the hexagram image of "thunder beneath the earth" (雷在地中), Cheng Yi's interpretation proves most accurate.

This passage from Tianyuan Fawei discusses the manifestation of the "Return Hexagram" (one of the 64 hexagrams in the Yijing, symbolizing the rebirth of yang energy) in human affairs. Master Zhu Xi explains that just as heaven and earth undergo the waxing and waning of yin and yang, the human mind also experiences the cyclical return of good and evil. Ordinary people often see the resurgence of negative thoughts, whereas the sage maintains a childlike purity of heart, perpetually united with the Dao (the Way), free from the fluctuations of good and evil.

Here, distinctions are made among different types of "return": the virtuous swiftly correct their faults ("returning without straying far"), while petty individuals persist in delusion ("returning in confusion"). Someone once asked Zhu Xi, "When a thought arises from absolute stillness, is this 'return'?" He replied that it cannot be generalized—one must distinguish between the return of good and evil and the return of stillness and movement. Just as the daytime mind may be bound by worldly affairs ("fettered and lost"), yet in moments of sudden awakening, compassion naturally stirs—this exemplifies the yin-yang transformation of good and evil. Similarly, movement arising from extreme stillness represents the yin-yang alternation of stillness and movement.

The human mind is originally clear and bright. One should nurture the good thoughts detected in stillness and uproot the evil ones noticed in activity. Gradually eliminating human desires while preserving heavenly principle (tianli), one may progress from the ordinary state of "having return" toward the sage's realm of "no return."

Using the six lines of the Return Hexagram as metaphors: the initial yang line, "returning without straying far," corresponds to Yan Hui (whom Confucius praised for "never repeating a mistake"). Though the other five lines do not explicitly reference specific figures, they contain implicit admonitions. For instance, Zixia's immediate correction upon hearing criticism reflects "auspicious return"; Zengzi's daily self-reflection embodies "frequent return"; and Qu Boyu's annual introspection represents "solitary return." In contrast, Lu Qi (a treacherous Tang dynasty minister), obstinate in his errors, exemplifies the ominous "returning in confusion." Yet none compare to Yan Hui's skill of "knowing the subtle signs" (anticipating omens), whose single day of self-restraint could restore benevolence to the world.

Finally, the hexagram statement "return comes in seven days" is explained as the cyclical pattern of the Dao's operation (Cheng Yi compares it to the yin-yang alternation of seasonal changes; detailed explanations appear earlier). While sages primarily teach the highest realization, they guide ordinary people through gradual cultivation.

This passage explores the fundamental principles governing celestial movements and the transformations of Yin-Yang. Zhang Zai (Hengquzi) observes that the seven-day cycle of day and night reflects natural law, as the cosmos operates in ceaseless continuity. Heaven and Earth revolve in perpetual cycles—appearing static yet eternally dynamic, maintaining this rhythm since the dawn of creation. The Dao follows its spontaneous course (Wuwei), impervious to human interference; forced alterations inevitably prove unsustainable.

Zhu Xi (Zhushi) elaborates: When Yin energy peaks (as in the Kun hexagram), Yang begins its resurgence. These dual forces cycle through the six lines of hexagrams, manifesting in daily, monthly, and annual rhythms. Ancient sages tracked celestial bodies starting from Altair, establishing midnight, winter solstice, and the Huangzhong musical pitch as calendrical foundations. Yang Xiong (Ziyun) developed this into the eighty-one sections of the Canon of Supreme Mystery, while Shao Yong expanded it into the theory of cosmic epochs—both attempting mathematical modeling of celestial ebbs and flows.

Cheng Yi (Chengzi) succinctly captures celestial mechanics, whereas Zhang Zai emphasizes Yang energy's relentless momentum—never extinguished even in deepest winter. Han scholars prioritized numerical patterns, calculating calendrical hexagrams through seven-day cycles correlated with winter solstice observations. Zhu Xi synthesizes: All existence stems from unified Qi, whose movement and stillness birth Yin-Yang. From celestial bodies to seasonal transitions, all phenomena embody this dynamic interplay. The Fu hexagram symbolizes Yang's nascent resurgence—faint as silk yet containing the complete celestial cycle.

Integrating multiple Neo-Confucian perspectives, the core teaching emerges: Natural laws manifest through Yin-Yang fluctuations, calculable yet fundamentally spontaneous (Wuwei). Humanity should harmonize with—not forcibly alter—these celestial rhythms.

This passage employs metaphors and hexagram imagery to discuss the waxing and waning interplay of Yin and Yang. Just as a single point of white in darkness allows one to perceive the surrounding blackness—akin to how the earth cannot conceal the sun's radiance even before dawn—so too in human affairs we find parallels. Consider Yan Hui (Confucius' disciple), who appeared dull among three thousand students yet none could deny his virtue. Zhu Xi observed that when a good thought first sprouts in a person's mind, however tiny, no amount of evil can suppress it.

Master Xu explains that the "Return" hexagram (Fu, symbolizing Yang Qi's resurgence) represents the pivotal moment for reverting to goodness. One must carefully discern this opportunity when a thought first arises—known only to oneself before others perceive it—and consciously return to the virtuous path. Following this principle makes one a noble person (junzi); violating it makes one petty (xiaoren). Failing to discern the essence of things leads to catastrophic errors—how can we not approach this with reverence?

Cheng Yi (Master Cheng) maintained that Yang Qi never fully vanishes; when it wanes above, it simultaneously grows below without interruption. Just as when the "Peeling" hexagram (Bo, representing Yang's decline) reaches its extreme and becomes pure Yin (the Kun hexagram), Yang Qi is already gestating anew. Aligning months with hexagrams, the tenth month corresponds to Kun—seemingly devoid of Yang, yet secretly nurturing its growth, hence its alternate name "Yang Month."

Zhu Xi further clarifies that the solitary Yang line in the Return hexagram doesn't emerge abruptly but accumulates gradually through Kun's phase. Like the moon's thirty-day cycle, Return's Yang Qi disperses across the month, accumulating daily increments from mid-tenth month after Minor Snow. Yin-Yang fluctuations mirror lunar phases—only after thirty days is the cycle complete. Kun never lacks Yang Qi entirely; its nascent energy simply remains too subtle to form a complete Yang line. This isn't abstruse philosophy—Cheng Yi originally failed to articulate how "Yin and Yang perpetually wane and wax in inseparable unity."

Through hexagram transformations, this text illuminates nature's constant interplay where Yin and Yang perpetually transform and counterbalance each other. Using everyday analogies, it emphasizes how virtuous thoughts and righteous Qi, however faint, can never be fully extinguished and will inevitably resurge.

The Tianyuan Fawei primarily discusses the waxing and waning patterns of Yin-Yang, using the winter solstice and lunar phases to explain the gradual transformation between these forces.

At midnight (11pm-1am) during the winter solstice, Yang Qi begins to germinate, yet this represents only the initial formation of a single Yang line. Subsequently, Yang energy grows incrementally by one-thirtieth each day, requiring a full month to complete the second Yang line. Just as the moon's phases require thirty days to transition from the Guan hexagram to the Bo hexagram, and another thirty days from Bo to Kun, Yang Qi similarly accumulates gradually—only on the winter solstice day does a complete Yang line truly form.

The transformation between Yin and Yang occurs progressively, never abruptly. Consider the top Yang line in the Bo hexagram being divided into thirty portions: each day one portion diminishes until completely vanishing by the ninth month's end. The growth of Yin Qi follows the same principle, observable through the Gou hexagram, though ancient scholars didn't explicitly state this.

The Qi between heaven and earth operates through six layers. At winter solstice, Yang Qi begins growing from the bottom layer, ascending over six months to reach the sixth layer (corresponding to the fourth lunar month)—the zenith of Yang that immediately begins declining. This is actually the same Qi circulating through the six layers: when Yang expands, it doesn't recruit external Yin energy; rather, the receding portions of Yang naturally transform into Yin. Thus Yang's return is called "Fu" (restoration to original state), while Yin's arrival is termed "Gou" (fortuitous encounter).

The bottom line of the Fu hexagram represents movement. Master Cheng Yi remarked that scholars throughout history believed stillness revealed heaven-earth's true heart, yet he alone advocated perceiving it through motion. When asked whether one should seek stillness within movement, he affirmed this—yet the true challenge lies in maintaining stillness before joy, anger, sorrow, or pleasure arise. Here we may call it stillness, but how then to comprehend the "movement" inherent within?

This passage explores the principles governing the movement of heaven and earth and the transformations of Yin-Yang. It begins by discussing the concept of "stillness," explaining that a completely unconscious state cannot be considered true stillness—real stillness exists before thoughts arise. Just as trees appear motionless while undergoing constant internal changes, with old leaves falling as new buds emerge, all things in heaven and earth are perpetually transforming. These changes occur not only over years and months but even within hours, minutes, and seconds, though most people remain unaware of them.

The metaphor of "the unplucked fruit" illustrates how an uneaten fruit contains the principle of renewal within it. Like the hard pit of a peach or apricot, which may seem lifeless on the outside, the seed inside holds the potential for new life. This embodies the benevolent heart of heaven and earth in creating all things—nothing is truly dead. The Book of Changes (Yijing) expresses this idea in the Fu (Return) and Qian (Heaven) hexagrams: when decay reaches its extreme, renewal follows, just as Yang energy regrows beneath the earth, much like a fallen fruit giving rise to new life.

Cheng Yi (Master Yichuan) explains that "returning in seven days" reflects the inevitable law of reversal at extremes—where there is birth, there must be death; where there is beginning, there must be end. The contraction and expansion, the coming and going of Qi (vital energy), follow natural principles without need for forced distinctions. It is like metal being smelted in a great furnace: as the old Qi dissipates, new vital energy naturally arises. The creative transformations of heaven and earth operate in this ceaseless cycle—as old Qi scatters, new Qi is born, revolving endlessly without exhaustion.

This scripture primarily explores the principles of Yin-Yang waxing and waning and natural cycles. The Yang Qi (vital energy) between heaven and earth resembles ocean tides—when the sun rises, the tide recedes (symbolizing the dissipation of Yang Qi), and when the moon rises, the tide returns (symbolizing the stirring of Yin Qi). Zhu Xi (Master Zhu) used the phrase "returning after seven days" not to suggest the return of past Yang Qi but to indicate the spontaneous emergence of new Yang Qi. Just as the great De (Virtue/Power) of heaven and earth operates eternally, and rivers flow unceasingly, there is no need to rely on dissipated old Qi to nourish new life.

Cai's interpretation explains that Yang Qi begins to wane in the Wu month (the fifth lunar month) and starts to regenerate in the Zi month (the eleventh lunar month), a process spanning seven hexagram lines (symbolizing changes in trigrams) or seven months. Guo further elaborates that the initial Yang line of the Qian hexagram (symbolizing the birth of Yang Qi) corresponds to the midnight of the winter solstice in the Jiazi year, when the movements of the sun, moon, and stars are recalculated starting from the Ox constellation (one of the Twenty-Eight Mansions). The Huangzhong pitch (the first of the Twelve Pitches, corresponding to the winter solstice) is the root of all growth—when Yang Qi ascends, all things flourish; when Yin Qi ascends, all things wither.

Li adds that when Yin Qi emerges in the Wu month (the fifth month), the sun moves to the south, and when Yang Qi regenerates in the Zi month (the eleventh month), the sun moves to the north, marking the winter solstice. The newly born Yang Qi, though as faint as a strand of hair, requires seven days (an ancient cyclical period) to accumulate sufficient strength. Just as plants wither and fruits fall to the ground, new vitality sprouts again from their seeds. The Yu hexagram speaks of acting in accordance with the moment because principle precedes Qi movement, while the Fu hexagram speaks of returning to the right path amid movement, embodying the ceaseless generative laws of heaven and earth.

Note: The terms "Jianwu month" and "Jianzi month" are ancient calendrical terms referring to the months containing the summer and winter solstices, respectively; "Seven Regulators" refers to the sun, moon, and the five planets (Venus, Jupiter, Mercury, Mars, and Saturn); "Ox" is one of the Twenty-Eight Mansions; and "Huangzhong" is the first of the Twelve Pitches, corresponding to the winter solstice.

This passage elucidates the correspondence between celestial movements and human respiration. Liu Shi (possibly the Han dynasty scholar Liu Xiang) proposed that celestial phenomena operate through twelve directional positions, with Yin and Yang each occupying six positions. When Yang energy reaches the seventh position, it returns to its origin—this cyclical pattern applies equally to calculations of years, months, days, and hours.

Han scholars employed the transformations of the Qian and Kun hexagrams (the fundamental trigrams representing Heaven and Earth in the Yijing) to reckon time: a day cycles from noon through midnight back to the zi hour (11 PM–1 AM); a year progresses from the fifth month through the eleventh month back to the zi month (the eleventh lunar month); and seven years form a complete cycle from the noon year back to the zi year. The Dao of Heaven naturally manifests this rhythm, with sixty hexagrams corresponding to 360 days, each pair of hexagrams separated by seven days. When the sages emphasized "returning in seven days" in the Fu hexagram, they were illustrating the operational principle of hexagram-Qi (the energy correspondence between hexagrams and solar terms).

Someone once asked Shao Yong (the Northern Song Neo-Confucian philosopher) about the respiration theory concerning the two solstices. The explanation states: after the winter solstice comes exhalation, after the summer solstice comes inhalation. During exhalation, all things flourish; during inhalation, all things return to storage. One annual respiration constitutes Heaven-Earth's grand opening and closing. The zi hour (11 PM–1 AM) in midnight marks exhalation, while the shen hour (3–5 PM) in afternoon signifies inhalation—respiration harmonizes with Yin-Yang transformations. Humans undergo 13,600 respirations daily: daytime exhalation corresponds to worldly activity, while nighttime inhalation brings universal stillness. Heaven-Earth's patterns manifest in the human body—breathing relates to speech and movement, with the Fu and Gou hexagrams (representing Yang ascent and Yin retreat) mutually transforming as Yang energy rises and Yin recedes.

Ultimately, even the 129,600-year cosmic cycle (Yuan cycle proposed by Shao Yong) constitutes but a fleeting moment within the vast flow of cosmic transformation. Through correlating astronomical calendrics with human respiration, this passage expounds the Daoist philosophy of Heaven-human resonance.