On Yin–Yang Circulation in Meng Xi and Jing Fang’s Gua-Qi Theories and Its Influence

Zhang Chunxiang

Abstract： During the Han dynasty， the main current in the studies of the Book of Changes was the image–numerology school founded by Meng Xi and Jing Fang， which attempted to explain the Changes through gua-qi theories of the circulation of yin and yang that regarded generation and circulation as the essence of the Way of the Changes. Specifically， by drawing on astronomical calendrical knowledge， they established a generative philosophical system in which， as they claimed， on the basis of the circulation of yin and yang one could deduce climatic changes in the four seasons of the year could be deduced and thereby foretell good or bad luck in human affairs. Their efforts represent a creative interpretation of the ideas that “the great virtue of heaven and earth is the production and reproduction of life” and “production and reproduction is what is called change” advocated by pre-Qin studies of the Changes， and around this core concept of the circulation of yin and yang they constructed a generative mode of thinking about the cosmos， heaven and earth， and society and life.

Keywords： gua-qi theory， generation， yin–yang

The pre-Qin theories of gua-qi （卦氣說） became the mainstream or basic theory of the studies of the Book of Changes in the Han dynasty （206 BCE–220 CE）. Contemporary scholars have made considerable achievements in studying those theories， such as Liu Dajun 劉大鈞， who focuses on its historical origins， and Wang Xinchun 王新春， who pays more attention to tracing its historical evolution and philosophical significance it implies， highlighting the meaning of the sixty-four hexagrams as symbols. Both studies are based mainly on academic analysis of the theories history and value. In contrast， the present essay is a philosophical attempt to study the concept of the circulation of yin and yang put forth by Meng Xi 孟喜 （ca. 90–40 BCE） and Jing Fang 京房 （77–37 BCE） in their theories of gua-qi and that concepts influence on the later development of the dominant intellectual structures of ancient Chinese thought.

Source of the Theories of Gua-Qi [Refer to page 16 for Chinese. Similarly hereinafter]

Though theories of gua-qi were popular in studies of the Changes in the Han dynasty， it emerged earlier. Liu Dajun， who studied the new unearthed bamboo slip and silk manuscripts， is of the opinion that theories of gua-qi was developed before the Qin dynasty （221–207 BCE）.

What is meant by gua-qi？ The character gua 卦 has two meanings： it can refer to the eight trigrams—namely Qian 乾 （heaven）， Kun 坤 （earth）， Zhen 震 （quake）， Xun 巽 （wind）， Kan 坎 （water）， Li 離 （fire）， Gen 艮 （restraint）， and Dui 兌 （joy）—or to the sixty-four hexagrams. Qi 氣 has also two meanings： one is jieqi 節(jié)氣 （solar terms， i.e.， the twenty-four divisions of the solar year in the traditional Chinese calendar） and the other， the vital forces of yin and yang （the two opposing but complementary principles in nature， according to traditional Chinese philosophy）. Theories of gua-qi developed to correlate the eight trigrams or sixty-four hexagrams with the twenty-four solar terms of the four seasons. Furthermore， with the twelve months and with the three hundred and sixty-five days of the solar year， and， taking into account the changing odd–even numbers as yin–yang symbols， it was used to explain the change and rotation of the years solar terms and seasonal variations in climate. In the history of Han dynasty studies of the Changes， there are two gua-qi theories， one organized around eight trigrams and the other around the sixty-four hexagrams.

The gua-qi theory of eight trigrams dates back to “Explaining the Trigrams” [說卦] in the Book of Changes.

The myriad things come forth in Zhen; Zhen corresponds to the east. They are set in order in Xun; Xun corresponds to the southeast. “Set in order” means that they are fresh and neat. Li here means brightness. That the myriad things are made visible to one another here signifies that this is the trigram of the south. The fact that the sage king faces the south to listen to the whole world and that he turns toward the brightness there to rule is probably derived from this. Kun here means the earth. The myriad things all are nourished to the utmost by it. This is why it is said “it gives them maximum support.” Dui here means autumn at its height， something in which the myriad things all find cause to rejoice. This is why it is said “it makes them happy.” As for “has them battle in Qian，” Qian here is the trigram of the northwest， so this signifies where yin and yang exert pressure on each other. Kan here means water. It is the trigram of due north. It is the trigram of wearisome toil. It is here that the myriad things all find refuge. This is why it is said， “It finds them thoroughly worn out in Kan.” Gen is the trigram of the northeast. It is here that the myriad things reach the end of their development， but it is also the beginning of that development. This is why it is said “it has them reach final maturity in Gen.”

In this chapter， the eight directions are defined; but as for the seasons， the chapter says only that “Dui here means autumn at its height，” without mentioning the other three seasons. This schema of the eight trigrams can be seen as the earliest instance of the gua-qi theories. The theory of four cardinal trigrams （正卦） and four midway trigrams （維卦） that developed later serves as further basis for the inception of further gua-qi theories in the Han dynasty. According to that theory， the four trigrams of Zhen， Li， Dui， and Kan correspond to the four cardinal directions due east， south， west， and north respectively， and to spring， summer， autumn， and winter at their heights; and it is for this reason that they are called the cardinal trigrams. In contrast， the other four trigrams of Xun， Kun， Qian， and Gen pertain to the four midway directions of southeast， southwest， northwest， and northeast and the four points of seasonal transition; hence they are called the midway trigrams. This schema reflects not only the special changes of the eight directions （i.e.， the east， south， west， and north and the southeast， southwest， northwest， and northeast） but also the passage of time and changing of the seasons. Thus in light of this theory， the myriad things in nature are correlated in time and space， and with the passage of time and with circulation in space， they are always connected with one another in a flow that never ends. In its early stage， the gua-qi theory of the eight trigrams had formulated these characteristic concepts of four cardinal and four midway trigrams， convertibility of time and space， the circulation of yin and yang， and the generative and circulating Way of Changes. Meng Xi and Jing Fangs studies of the Changes are characterized by their attempts to explain the Changes with the concept of yin–yang circulation in their gua-qi theories， which defined generative circulation as the essence of the Way of the Changes.

Meng Xis Gua-Qi Theory [16]

Meng Xi was the first to advocate gua-qi theory in the Han dynasty. On the basis of the earlier gua-qi theory of the eight trigrams， he developed a fresh theory concerning the sixty-four hexagrams， proposing a completely new explanation of the four cardinal trigrams.

The period from the beginning of the Winter Solstice （the twenty-second solar term） can be correlated with the hexagram Zhongfu 中孚 （inner trust）， and the number of days in a month happens to be the sum of the four numbers of nine， six， seven， and eight used in divination. Every month of the year can be correlated with five hexagrams， each governing a period of six days. Five days are counted as a pentad （hou 候）， and five times six is thirty， which is the number of days in a month， at the end of which occurs the change to the coming month. Thus twelve such changes represent the twelve months of a year. Of the four trigrams of Kan， Li， Zhen， and Dui， each line governs one of the twenty-four solar terms in sequence. . . . Therefore all the changes of the four seasons involve the six lines of each hexagram， and their responses to the twenty-four solar terms are complete.

The earliest mentions of the twenty-four solar terms and seventy-two pentads can be found in such ancient documents as “Proceedings of Government in the Different Months” [月令] in the Book of Rites， “Twelve Periods” [十二紀(jì)] in Lüs Commentary on the Spring and Autumn Annals [呂氏春秋]， and “Patterns of Heaven” [天文訓(xùn)] and “Months of Seasons” [時則訓(xùn)] in the Huainanzi [淮南子]. In the Han dynasty， when Meng Xi attempted to apply the sixty-four hexagrams to explain the changes of the solar terms in a lunar year， he proposed his theory of the four cardinal hexagrams and the twelve sovereign hexagrams （辟卦） and， by correlating the seventy-two pentads with the sixty hexagrams other than the four cardinal ones， he discussed the generative yin–yang circulation underlying the characteristic changes in weather throughout the year.

Four Cardinal Hexagrams and the Generative Circulation of the Twenty-Four Solar? Terms [17]

Meng Xi correlated the four cardinal hexagrams of Kan， Li， Zhen， and Dui with the images of the four seasons of spring， summer， autumn， and winter.

In his theory， the trigrams of Kan， Zhen， Li， and Dui， which are ?， ?， ?， and ? respectively， represent due north， east， south， and west. Of their bottom lines， the first is a broken or yin line （SIX in the first position） and the other three are all unbroken or yang lines （NINE in the first position）. These bottom lines symbolize the Winter Solstice which is the middle point of the eleventh month， the Spring Equinox at the midpoint of the second month， the Summer Solstice at the midpoint of the fifth month， and the Autumn Equinox at the midpoint of the eighth month.

The transition points between winter， spring， summer， and autumn are represented by the bottom lines of the four cardinal hexagrams and called Winter Solstice， Spring Equinox， Summer Solstice， and Autumn Equinox respectively. Around those points， the gradual seesawing change between yin and yang occurs and correspondingly the odd–even numbers also undergo change. Thus such changes of yin–yang and odd–even numbers indicate the generative circulation of the four seasons， one such cycle making one year. Thus， one year is divided into twenty-four solar terms and one month occupies two solar terms. The four cardinal hexagrams， each formed from a doubling of the cardinal trigrams， have twenty-four lines in total， which correspond to the twenty-four solar terms， respectively.

Twelve Sovereign Hexagrams and the Generative Circulation of Twelve Months [18]

Table 1. Seesawing yin and yang indicated by the twelve sovereign hexagrams

Lunar month Season Hexagram name Hexagram Yin and yang configuration

Eleventh month Second month of winter Fu 復(fù) （return） One yang， five yin

Twelfth month Third month of winter Lin 臨 （overseeing） Two yang， four yin

First month First month of spring Tai 泰 （peace） Three yang， three yin

Second month Second month of spring Dazhuang 大壯 （great strength） Four yang， two yin

Third month Third month of spring Guai 夬 （resolution） Five yang， one yin

Fourth month First month of summer Qian Six yang

Fifth month Second month of summer Gou 姤 （encounter） One yin， five yang

Sixth month Third month of summer Dun 遯 （withdrawl） Two yin， four yang

Seventh month First month of autumn Pi 否 （obstruction） Three yin， three yang

Eighth month Second month of autumn Guan 觀 （viewing） Four yin， two yang

Ninth month Third month of winter Bo 剝 （peeling） Five yin， one yang

Tenth month First month of winter Kun Six yin

In Mengs theory， these twelve hexagrams， also called sovereign or monarch hexagrams （君卦） or rising and falling hexagrams （消息卦）， make up the trunk of the sixty hexagrams correlated with a lunar year， and he used the seesawing changes between yin and yang in those hexagrams （see table 1） to symbolize the rotation through the years twelve months. In the winter images， yin flourishes to the greatest extent and yang declines to its lowest ebb. This indicates the period of the great yin （太陰）. In the spring images， yang begins to rise and yin to decline， which indicates the period of lesser yang （少陽）. In the summer images， yang waxes maximally and yin ebbs to its lowest point， indicating the period of great yang （太陽）. And in the autumn images， yin begins to rise and yang to decline， indicating the period of lesser yin （少陰）. Thus the years four seasons run through a cycle of rising yang followed later by rising yin. From the numbers corresponding to yin and yang， four are picked out （i.e.， SEVEN and NINE for yang and EIGHT and SIX for yin）， which are referred to as lesser yang， great yang， lesser yin， and great yin. Meng uses broken and unbroken lines and odd and even numbers to represent yin and yang and applies the changes of the yin and yang lines in the hexagrams and of odd–even numbers to explain the rising and falling processes of yin and yang. In his theory， the cycle of the four seasons， twenty-four solar terms， and sixty-four hexagrams are all attributed to the waxing and waning movement of yin and yang.

The Generative Circulation of Sixty-Four Hexagrams and Seventy-Two Pentads [19]

Each of the twelve months in a year is divided into two solar terms， called jieqi 節(jié)氣 （node solar term） and zhongqi 中氣 （center solar term）. Thus there are twelve node solar terms and twelve center solar terms in a year. Each of the node and center terms is further divided into three pentads， for a total of seventy-two pentads in a year. Each has its own climate feature， which is called a response （ying 應(yīng)）. This division of a year into seventy-two pentads， each with its own characteristic climate change， was mentioned very early in “Seasons Explained” [時訓(xùn)] in the Lost Book of Zhou [逸周書]. Meng Xi improved the description of climatic changes represented in the seventy-two pentads and correlated them with the sixty non-cardinal hexagrams， leaving four cardinal hexagrams of Kan， Zhen， Li， and Dui unassociated with the pentads. In his system， the second pentad in the second solar term of each month is indicated with the lines of the twelve sovereign hexagrams， and the remaining forty-eight hexagrams are correlated with the other sixty pentads. Thus the six pentads in the two solar terms of a month are indicated with four entire hexagrams and two half hexagrams （one upper trigram and one lower trigram） and， to indicate the seventy-two pentads in the twelve months of the year， sixty hexagrams are used in total.

In Mengs gua-qi theory， Kan， Zhen， Li， and Dui are the four cardinal hexagrams and their bottom lines correspond respectively to the Winter Solstice， Spring Equinox， Summer Solstice， and Autumn Equinox， the four critical points where yin–yang changes occur. In Mengs words， “The static SEVEN of yang begins with Kan， and the dynamic NINE of yang begins with Zhen; the static EIGHT of yin begins with Li， and the dynamic SIX of yin begins with Dui.” Then he correlated the changes of the twenty-four lines of the four cardinal hexagrams with the yin–yang changes of the twenty-four solar terms， thus making the natural circulation of the four seasons and the yin–yang changes of the hexagram lines correspond perfectly with each other. This is what he meant when he said the aforementioned “all the changes of the four seasons involve the six lines of each [cardinal] hexagram.” By using the seventy-two pentads， he brought the specific responses of the four seasons into the other sixty hexagrams. This is what is meant by his “their responses to the twenty-four [node and center] solar terms are complete.” The other sixty hexagrams than the four cardinal ones are correlated with the twelve months of a year， and each month calls for five of them， which are referred to respectively by using five titles of nobility， that is， marquis， senior official， minister， duke， and sovereign. In this way， the circulation of yin and yang underlying the concrete beings on the physical level tallies with the evolution of the Heavenly Way for production and reproduction of life on the metaphysical level， and the Heavenly Way and the Human Way come into identity. So in the true sense， the Human Way is established on the basis of the Heavenly Way and humanity is created along the model of the Heavenly Way. All activities ranging from national governance to farming work to peoples conduct display life-creating processes， that is， those from the Heavenly Ways production and reproduction of life to that of the Human Way. Also displayed here is the characteristic philosophical feature of the commentaries of the Book of Changes， namely the unity of Heaven and humanity， something conveyed by the phrase “fully understanding the Heavenly Way and clearly ascertaining the experience of the people.” In addition， Mengs theory highlights the generative nature of Han dynasty studies of the Changes and even of the whole of Confucian philosophy.

Jing Fangs Gua-Qi Theory [21]

Jing Fang was the most important of the scholars who advanced the thriving of the study of the image–numerology of the Changes in the Western Han dynasty （206 BCE–25 CE）. He created many divinatory calculation patterns on the basis of his understanding of the divinatory rules set up in the Book of Changes. Underlying all these patterns was his basic concept of the circulation of yin and yang and generation. He inherited Meng Xis gua-qi theory and applied that concept to interpreting the proposition that “the successive movement of yin and yang constitutes what is called the Way，” which best represents his way of thinking concerning the Changes.

‘Each Component Trigram of the Eight Cardinal Hexagrams Is Attributed to Yin or? Yang and the Six Positions Are Correlated with the Five Elements [21]

Jing Fang arranged the sixty-four hexagrams in the order of the eight houses and thereby illustrated the changes of the hexagram line images as the waxing and waning process of yin and yang， thus deepening Meng Xis gua-qi theory.

Each main hexagram of the eight houses is comprised of the doubling of two identical trigrams. The order of these eight house hexagrams， also called the eight pure hexagrams， is Qian， Zhen， Kan， Gen， Kun， Xun， Li， and Dui. Of these， Qian and Kun are the father and mother hexagrams respectively， each leading three sons and daughters. Zhen， Kan， and Gen are the first， second， and third sons， and Xun， Li， and Dui are the first， second， and third daughters. Each main hexagram of the eight houses leads seven other hexagrams and each house contains eight hexagrams. Thus beginning with Qian and ending with Guimei 歸妹 （marrying maid）， the sixty-four hexagrams are separated into eight houses led by the eight pure hexagrams. In each house， every hexagram has its own position and these positions are divided into eight categories， that is， top generation （the eight pure hexagrams）， first， second， third， fourth， and fifth generations， wandering soul， and returned soul. The eight hexagrams in each house are generated from the positional changes of the lines in the eight pure hexagrams in the top generation. There are two types of line changes， namely from yin to yang and from yang to yin， which are the mutual transformations between yin and yang. For example， when the bottom yang line of Qian （） changes into a bottom yin line， the hexagram changes into another hexagram of Gou （）. Thus when such a line changes from yang to yin or vice versa， the result is a different hexagram， which is one in the first generation. If both the bottom yang line and the second yang line of Qian change to yin ones， the hexagram changes into Dun （）， a different hexagram of the second generation. In a similar fashion， the changes resulting in the other hexagrams in this house and the hexagrams in all other houses can be known. To improve the efficacy of divination， Jing went further and proposed three more theories， which he brought into his system of eight houses.

First was the shiying 世應(yīng) （generation–response） theory. In this theory of Jing， the six lines of a hexagram， from the bottom to the top， correspond to the six grades in the framework of an imperial court （i.e.， bottom scholar， senior official， the Three Dukes， princes or dukes， the Son of Heaven， and the royal ancestral temple）. According to him， when practicing divination， the diviner needs only to judge the dominant line for a determination of good or ill luck. The dominant line of a first generation hexagram is the bottom scholar， the dominant line of a second generation hexagram is the senior official， and so on. As for the eight pure hexagrams， their dominant lines are their top lines. These dominant lines are called by such names as jushi 居世 （residing generation）， linshi 臨世 （downward-looking generation）， and zhishi 治世 （ruling generation）. The responses corresponded to the generations and among the line positions， the correspondences are between the first （bottom） and fourth， second and fifth， and the third and the top. With such clearly defined positions of the dominant lines for divination and host–guest correspondences， the diviner could determine the images symbolizing good or ill luck according to the generation–response relationships.

Second was the feifu 飛伏 （manifest–latent） theory， which is concerned with both the image of an entire hexagram and the images of its lines. When explaining the hexagram of Qian， Jing wrote， “All the six positions of Qian are occupied by yang lines， but the image of yin lies within. Yang is the sovereign， and yin the subject; yang is the people and yin the affairs. With solid yang and empty yin， the image is either manifest or latent， by which yin and yang can be known.” According to this theory， “manifest and latent” mean that when yang is manifest， yin is latent， and vice versa. This is illustrated by Jings explanations of Qian and Kun： “Qian is manifest and meanwhile Kun is latent” and “Kun is manifest and meanwhile Qian is latent.” In this sense， when Qian （yang） is manifest， Kun （yin） is latent， and vice versa. Thus the good or ill luck in human affairs is attached to the generative circulation of the Heavenly Way and yin–yang.

Third was the theory of najia 納甲 （attaching the ten Heavenly Stems and twelve Earthly Branches to the eight pure hexagrams）. Here the main hexagrams of the eight houses are correlated with the ten Heavenly Stems and the lines with the twelve Earthly Branches. Jia 甲 being the first one of the ten Heavenly Stems， the name najia means “attaching jia.” Similarly， attaching zhi 支 （i.e.， the Earthly Branches） is what is meant by nazhi 納支. Jings Explanation of the Book of Changes [京氏易傳] states：

To the images of Heaven and Earth， Qian and Kun， are attached jia， yi 乙， ren 壬， and gui 癸. To the images of Zhen and Xun， Kan and Li， Gen and Dui， are attached geng 庚 and xin 辛， wu 戊 and ji 己， bing 丙 and ding 丁 respectively. Thus each component trigram of the eight cardinal hexagrams is attributed to yin or yang and the six positions are correlated with the Five Elements. Brightness shines in all four directions and the changes indicate the solar terms definitely.

Of the ten Heavenly Stems， jia， bing， wu， geng， and ren are the five yang ones and yi， ding， ji， xin， and gui， the five yin ones. Qian contains two component trigrams， of which the lower trigram is the inner one and the upper trigram is the outer one. Jia and ren are attached to the inner and outer trigrams respectively. Thus in the hexagram， jia indicates the beginning of yang and ren， the end of yang. In the same fashion， Kuns inner and outer trigrams are attached with yi and gui respectively， where yi indicates the beginning of yin and gui， the end of yin. Qian and Kun are the father and mother hexagrams， which serve as the gate and leader for all other six hexagrams. This is what is meant by the aforementioned saying that “each component trigram of the eight cardinal hexagrams is attributed to yin or yang.” “The six positions are correlated with the Five Elements” is a reference to nazhi. Of the twelve Earthly Branches， zi 子， yin 寅， chen 辰， wu 午， shen 申， xu 戌 are the yang ones， and chou 丑， mao 卯， si 巳， wei 未， you 酉， hai 亥 are the yin ones. The lines of the male hexagrams from bottom to top are attached to the yang branches， which are prograde， and the lines of the female hexagrams are attached to the yin branches， which are retrograde. This is what is meant by the six positions correlated with the six lines. Then the Five Elements are attached to the eight house hexagrams; that is， Qian， Kun， Zhen， Kan， Li， Gen， and Dui are attached to Metal， Earth， Wood， Water， Fire， Earth， and Metal respectively. According to the correlation between the Five Elements and the Earthly Branches， they can be attached to the six lines of each hexagram. In this way， when the Heavenly Stems correlate with the eight cardinal hexagrams form combinations with the Earthly Branches， respectively， the process of najia can be said to be complete.

Thus the natural evolution of the Heavenly Way is reflected in the circulation and generation of the eight hexagrams in each house， and meanwhile the dominant lines for divination and host–guest correspondences are brought into each house and have their correspondent combinations of the Heavenly Stems and Earthly Branches. This means that the generation and evolution of the Human Way and human affairs are also reflected in the changes of the eight hexagrams in each house. Therefore when yin–yang and the Five Elements were attached to the Heavenly Stems and Earthly Branches， and to the eight house hexagrams and the six lines of each hexagram therein， and when this was used to explain the changes of the Heavenly Way and human affairs， the result would be for “brightness [to] shine in all four directions and the changes [to] indicate the solar terms definitely.” That is why Jing said that “the generation of the meaning of good or ill luck begins with the Five Elements and ends with the hexagrams of eight houses.” The Heavenly Way and the Human Way come into unity naturally in the evolution of the eight houses and the eight hexagrams in each house， in the sense that the changes of the Heavenly Way and the auspiciousness and inauspiciousness of the Human Way become interconnected， thus realizing the unity of Heaven and humanity.

‘The Interaction between Yin and Yang Gives Rise to Images [24]

From the concept of yin–yang in the Book of Changes， Jing developed his qi theory of yin and yang （as two vital forces）. In his opinion， the interaction between yin and yang is “an unceasing process of renewing and reproducing，” and he gave a new explanation of “the successive movement of yin and yang constituting what is called the Way，” as is said in the Book of Changes.

In divinatory calculations， with the arrangements of the hexagrams， the houses are formed， where Qian， Kun， Zhen， Xun， Kan， Li， Gen， and Dui activate each other and yin and yang interact unceasingly， one penetrating into the other. Thus it is said that “production and reproduction is what is called change，” meaning that all between heaven and earth penetrate one another.

（When explaining Kun， he says） yin and yang， the two vital forces， connect heaven and earth together and their images indicate the good or ill luck in human affairs; with the changing six positions in the hexagrams， whether one of their component hexagrams is yin or yang can be known. Yin， though empty in nature， becomes solid when attached to a yang position. Never static， yin rises when yang falls and yang rises when yin falls， with the myriad of changes. That is why this seesawing process is called by yi 易， which means changes.

Jings explanation of “production and reproduction as what is called change” through his theory of yin and yang can be understood with regard to the following three points.

First， what constitutes the basis of production and reproduction is yin and yang. When Jing represented the abstract yin and yang with concrete and dynamic qi， he offered a specific form for explaining the process of production and reproduction as well as changes， and according to him， only qi can penetrate everywhere and into everything between heaven and earth.

Second， the mode of production and reproduction is the unceasing interaction of yin and yang. He proposed many modes of interaction between the two， such as crossing， contesting， converging， rising and falling， and growing and declining.

Third， the relationship between yin and yang is one of mutual transformation and the meeting of their extremes is a way of production and reproduction.

It is their interweaving and inter-activating， conflicting and converging， rising and falling， and growing and declining that bring about the changes of the hexagram images and of good or ill luck in human affairs. In the proposition that “the successive movement of yin and yang constitutes what is called the Way，” the Way refers to both the Heavenly Way and the Human Way， and what connects them is none other than yin and yang. The interaction between yin and yang means their pushing each other in their circulation， and their changing never stops in this continuous process of production and reproduction. This is what is meant by “production and reproduction as what is called change.”

‘Looking Up and Observing Down Are Matters of Humankind; Hiding or Showing， Ill? or Good Luck Depend on Heaven [25]

In his study of the Changes， Jing Fang was adept in foretelling disasters， for example divining wind， rain， heat， and cold by using hexagram images and talking about yin–yang indications of disasters or abnormal phenomena. In Jings Explanation of the Book of Changes， he writes，

The generation of the meaning of auspiciousness and inauspiciousness begins with the Five Elements and ends with the hexagrams of the eight houses. In turning from non-being into being， disaster can be foretold by observing the stars， while in turning from being into non-being， the images of yin and yang can be seen. . . . The upper and lower lines in a hexagram， and the Heaven and Earth with yin and yang， change to show images of being and non-being， which can be correlated with human affairs. With regard to the hexagrams of the eight houses， looking up and observing down are matters of humankind; hiding or showing， good or ill luck， depend on Heaven; considering timing and inspecting human affairs depends on the hexagrams.

Jing tried to foretell good or ill luck by astronomic and climatic changes. In his “turning from non-being to being，” the “non-being” in question refers to the invisible images of good or ill luck and “being” to the visible changes of the sun， moon， and stars. In his phrase “turning from being into non-being，” “non-being” refers to the abstract changes of yin and yang. The division of a year into solar terms is based on the circulation of yin and yang， and this circulation determines the good or ill luck in human affairs. Therefore the changes of the lines in a hexagram， as heaven， earth， and stars change， also forebode the good or ill luck， weal or woe， in human affairs.

By introducing the theory of Heaven–humanity interaction into his gua-qi theory， Jing Fang bound the Heavenly Way and human affairs together in close relationship， shifting the focus of Meng Xis gua-qi theory from the Heavenly Way to the good or ill luck in human affairs. This represents his creative application of “fully understanding the Way of Heaven and clearly ascertaining the experience of the people，” as is said in “Appended Remarks I” in the Book of Changes， displaying a heavily religious color. His theoretical model of the eight pure hexagrams leading the sixty-four hexagrams highlights the seesawing growth and decline between yin and yang in a dynamic end-to-end circulation which extends infinitely， on the basis of which his explanation of the cosmos and life is structurally more reasonable and more systematic.

The Influence of Meng Xi and Jing Fangs Gua-Qi Theories [25]

In the Han dynasty， gua-qi theories were the mainstream of the studies on the image–numerology of the Change， and Meng and Jing were the most important scholars in the historical development of the gua-qi theories and even the ancient Chinese studies of the image–numerology of the Changes， Meng as the initiator of the theory and Jing as the person who improved and systematized it. Their core position is salient in the following three aspects.

First， taking the circulation of yin and yang as their basic way of thinking， they constructed the generative philosophical system for Han thinking concerning the Changes， which set up the most fundamental intellectual structure for explaining the cosmos， heaven and earth， and society and life. One of the main features of Meng Xi and Jing Fangs studies was to explain the Changes using the circulation of yin and yang highlighted in their gua-qi theories to reveal generative circulation as the essence of the Way of the Changes. Specifically， by applying their gua-qi theories and drawing on their astronomical and calendrical knowledge， they established a generative philosophical system where the circulation of yin and yang serves as the basis for deducing the climatic changes in the four seasons of the lunar year and further foretelling good or ill luck in human affairs. This represents their creative interpretation of the ideas that “the great virtue of heaven and earth is the production and reproduction of life” and that “production and reproduction is what is called change，” as proposed by pre-Qin studies of the Changes， and meanwhile their creation for later scholars of the generative mode of thinking with yin–yang circulation as the core. Their mode of thinking set up the most basic intellectual structure by which later scholars would explain the cosmos， heaven and earth， and society and life. That is， they would apply the concept of dynamic yin–yang circulation to probing the infinite changes of the cosmos， heaven and earth， contemplating trends in the development of human society， and understanding the vicissitudes of an individual life. It indicates the structural， systematic， and holistic features characteristic of Han dynasty studies of the Changes， marking the complete formation of the generative thinking mode of ancient Chinese philosophy.

Second， Meng Xi and Jing Fangs gua-qi theories pervaded later social life. With their theories they deduced for later generations a schema generative of changes theoretically based on the circulation of yin and yang. In other words， they proposed a method， a way， or a specific mode for explaining the course of the cosmos and of life. Their gua-qi theories contributed much to the development of generative thinking in studies of the Changes and even of the intellectual style of ancient Chinese philosophy at large， a style that also penetrated into the daily life of common people and their farming activities， thus exerting great influence on later generations. The philosophic system revolving around the Changes and centered on the gua-qi theories， in combination with such specific subjects as astronomy， almanacs， medicine， and agriculture， was applied widely in various fields of society and life. After them， the study of the Changes entered a period of turning to the life of common people and using a more structural model based on the Changes whole holistic generative character is salient.

Third， Meng and Jings gua-qi theories made contributions to the development of the theory of divination based on the Book of Changes. Mengs explanation of the Changes is based on qi， and according to Qing scholar Hui Dong 惠棟 （1697–1758）， most Han dynasty Confucians applied the concept of gua-qi when practicing divination and took seasonal changes in nature as the topmost law manifesting the operation of the Heavenly Way. Meng Xi and Jing Fangs theories of gua-qi， as a divinatory system， influenced later practices of divination， especially the well-conceived construction of the system， and contributed to completing the image–numerology logical system of ancient China.

Nonetheless， the Han dynasty was also noted for abuses in annotating ancient classics， including the Book of Changes， which was then respected as the head of the Five Classics，i though that abuse took a different form from that of other classics. As the mainstream of Han dynasty studies of the Changes， Meng Xi and Jing Fangs theories of gua-qi， despite their refined and exquisite structures， also failed to free themselves from verbosity.

Bibliography of Cited Translations

Legge， James， trans. Book of Changes. http：//ctext.org/book-of-changes， accessed December 2， 2020.

Lynn， Richard， trans. The Classic of Changes： A New Translation of the I Ching as Interpreted by Wang Bi. New York： Columbia University Press， 1994.

Translated by Wang Xiaonong