Even if the Zhou 周 (11th cent.-221 BCE) culture was a mixture of different cultures of peoples that lived in the Wei River 渭水 valley in southern Shaanxi, after expanding their realm into the Yellow River Plain, the Zhou people keenly adopted the culture of the Shang 商 (17th-11th cent. BCE) people. Oracle bone divination, the use of sacrificial bronze vessels, and burying rites were taken over from the Shang. Yet there were also novel concepts.
The most important concept newly introduced by the Zhou people was the Mandate of Heaven (tianming 天命). The highest deity of the Shang people, Shangdi 上帝 (see Shang religion), was a rather impersonal figure which could not directly be influenced by sacrifices, and was to be distinguished from the dynastic ancestors. While Shangdi influenced the world rather generally, the "Heaven" of the Zhou was directly involved into political events, and its decisions or influence depended on the style of government of the Zhou rulers. Because the latter were "morally better" than the last Shang king Zhou 紂, Heaven gave the rule over the Central Plain into the hands of King Wu 周武王 of the Zhou, and took it away from the Shang.
|惟不敬厥德，乃早墮厥命。||For want of the virtue of reverence, the decree in its (the Shang's) favour prematurely fell to the ground. (Shangshu 尚書, ch. Zhaogao 召誥)|
|[殷王]誕淫厥泆。||[The king of Yin 殷 (i.e. Shang)] greatly abandoned to dissolute idleness. (ch. Duoshi 多士)|
Transl. Legge 1865.
The Zhou sometimes confounded the figure of Heaven with that of their own ancestors, namely in the way that the Zhou believed the Shang kings were not aware that the Mandate of Heaven would be taken away from them. The Heaven of the Zhou was not a "public Heaven", but only that of the Zhou themselves – even if early Zhou-period sources like the Classic Shangshu 尚書 "Book of Documents" occasionally call Heaven "Shangdi" (for instance, ch. Taishi 泰誓, Wucheng 武成) (Li 1994: 117).
The use of the concept of the Heavenly Mandate was a means of legitimization against the Shang, yet on the other hand, the Shangshu chapter Kanggao 康誥 warns that the Mandate would not be eternally given to the Zhou: "[Heaven's] appointments are not unchanging" (wei ming bu yu chang 惟命不于常). With almost the same words, the ode Wenwang 文王 in the Classic Shijing 詩經 "Book of Songs", warns that "the appointment of Heaven is not constant" (tian ming mi chang 天命靡常). The Mandate was, following the arguments of the Zhou, given to a dynasty which ruled by "moral" standards and based on a ritual system.
The Classic Shijing repeatedly (Xiaoya 小雅 "Lesser Odes": odes Tianbao 天保, Chuci 楚茨; Daya 大雅 "Greater Odes": odes Xiawu 下武, Juan'a 卷阿) claims that the kings of Zhou were "filial descents" (xiao sun 孝孫) and possessed "filialty and virtue" (you xiao, you de 有孝有德), for instance, by delivering the seasonal offerings (see Zhou religion) to their forefathers, so that King Wu's "filial mind was the model [for anyone else]" (xiao si wei ze 孝思維則). Filial piety meant not only reverence to living progenitors, but also to the ancestors, and required that one had to venerate them in the afterlife (zhuixiao 追孝, xiangxiao 享孝), care for the tombs and shrines, and deliver sacrifices. A complex system of terms for ancestral veneration evolved on the base of that of the Shang.
|予克紂，非予武，惟朕文考無罪。紂克予，非朕文考有罪，惟予小子無良。||[King Wu 周武王 said:] If I will subdue [King] Zhou [of the Shang], it will not be my prowess, but the faultless virtue of my deceased father [King] Wen 周文王. If Zhou subdues me, it will not be from any fault of my deceased father Wen, but because I, who am as a little child, am not good. (Fragment of Shangshu chapter Taishi, quoted in Liji 禮記, ch. Fangji 坊記)|
Transl. Legge 1885.
The Shang-period meaning of de 德 was "potency, force, effect", and represented and expression of the power of the Shang king over his subordinates and allies. The early character of de was 悳, showing how the "heart" 心 of the ruler was "straightly" 直 connected to that of his subjects. For this reason, the Shang kings had to tour their empire to keep up their authority (Sun 2015: 1-2). The character de (/tək/) 德 "virtue" is also seen as phonetically related to de (/tək/) 得 "to obtain, to occupy", meaning that it was an authority by which anyone was given his lot (Liu 1988; Chen, Xu 1989; Xu, Li 2000).
In Zhou-period texts like the relevant Shangshu chapters (Zhoushu 周書), the word de has two meanings, namely a relatively wide and unspecific meaning of "effect, force, value", like in the words jiude 酒德 "the [disempowering] force of wine", baode 暴德 "cruel government", Jie de 桀德 "an [evil] way [like that] of King Jie 桀 (the last ruler of the Xia 夏, 21th-17th cent. BCE)", or yide 逸德 "to exceed one's duty". This original meaning of de as "effective force" can still be seen in the expressions wende 文德 "virtue of culturedness" and wude 武德 "virtue of martiality", which were both to master by good rulers.
The other meaning of de was "virtue", like in the expression mingde 明德 "make clear the virtue", always with reference to the ancestors, Heaven, or the execution of punishments. The Zhou began to distinguish between "goodness" (mingde 明德, yide 懿德, wende 文德, jiade 嘉德, jide 吉德, lingde 令德) and "evilness" (hunde 昏德, luande 亂德, ede 惡德, liangde 凉德, baide 敗德, or bode 悖德).
The interpretation of the Zhou was that in the last phase of the Shang, their rulers tended to govern with "bad modes of virtue", stressing enforced power over governance with mildness, and investing more power into worldly fights than in sacrifices and communication with ancestral spirits and the High God. This step of interpretation was accompanied with a spiritualization of the word de (Sun 2015: 4): From a simple tool of demonstrating authority, de became a mode of governance sanctioned the superhuman power of Heaven. Yet still, de was related to the mode of government: The ruler's virtue "clarified the penal law" (ming xing 明刑) and "clarified the punishments" (ming fa 明罰). The Zhou ruler was "able to illustrate his virtue and be careful in the use of punishments" (ke ming de shen fa 克明德慎罰; Shangshu, ch. Kanggao).
The early Zhou conception of the term de includes four different realms (Wang 1997), namely the "virtue of Heaven" (tiande 天德), the "virtue of the ruler" (wangde 王德), the "virtue of his ministers" (chende 臣德), and the "virtue of the people" (minde 民德). The centre of these aspects of virtue was that of the ruler.
While for the Shang people, both the spirits of their ancestors and the High God were deities, and the Shang rulers were only executioners of the will of these deities, the Zhou took away from the spirits of their own ancestors the aura of numinosity, and at the same time de-mystified the role of Heaven and that of themselves. Heaven acted like a supreme ruler, whose executioners the Zhou were (Wang 1997: 9-10). Their way of government by virtue was ordered by Heaven, which therefore had also its principles of virtue. These could only be brought into the world by a dynasty ruling by means of virtue. The Zhou rulers thus alleged to simply obey the order of Heaven, punish the Shang for their "rule without virtue", and took over their empire.
When speaking of the ruler's virtue, the Shangshu texts stress the virtuous rule of the royal ancestors (xian wang zhi de 先王之德), mainly the "greatly distinguished father, King Wen 周文王" (pi xian kao/lao Wen Wang 丕顯考文王). They had executed a government of virtue "corresponding to [the will of] Heaven" (yi de pei tian 以德配天). The Zhou nonetheless somehow mistrusted Heaven (tian bu ke xin 天不可信, Shangshu, ch. Jun Shi 君奭,), insofar as the only chance to secure Heaven's mandate was to constantly stress that the Zhou would adhere to the virtue of their forefathers. The merit accumulated by previous generations would not suffice to guarantee Heaven's goodwill for any present generation of kings.
Among the ministers of the early Zhou, the Duke of Zhou 周公旦 was the most important. The Duke, reigning for King Cheng 周成王, therefore ordered the highest dignitaries to hold to the principles of virtue. At the same time, he reminded the King to appoint only ministers and counsellors which would be dedicated to the principles of virtue, and appealed to all functionaries and dignitaries of the Zhou court and the regional states to follow the King's moral orders. All these direct and indirect executioners of Heaven's will were not just to "respect Heaven" (jing tian 敬天; Shangshu, ch. Luogao 洛誥), but also to "protect the people" (bao min 保民, ch. Kanggao). Heaven would follow the desires of the people (tian qin yu min, min zhi suo yu, tian bi cong zhi 天矜於民, 民之所欲, 天必從之; Shangshu, ch. Taishi 泰誓 A), and in case of bad governance, punish the ruling dynasty.
The Duke not just admonished the king to venerate his ancestors, but also appealed to the courtiers and regional lords to take the late kings as a model of governance with virtue, meaning to use harsh punishments sparingly, pity the orphans and widows, see to it that everyone treated each other with respect, and serve the king. The Zhou kings therefore had constantly to have an eye on the people. Yet the concept of "virtue" also included a kind of self-cultivation and self-restriction. Fasting for certain periods, refraining from hunting, or taking the plough and working a certain tract of land, were therefore part of the cycle of ceremonial behaviour of the Zhou kings through the year (Li 1994: 112).
The four realms in which virtue was to be applied is a prove for the downward shift of the term "virtue" (de ; Wang 2016). While de was a means of rulership for the Shang kings, it was divided into a political ("good governance") and a private sphere ("self-cultivation", xiushen 修身), and could therefore be applied not just to the king, but also to his ministers and functionaries, and finally to everyone in the Zhou empire. The most important tool to promote a conduct of virtue was the introduction of the concept of "rites" (li 禮) as standards for ceremonies, behaviour and any other activities in the political and social realm. The concrete prescriptions of rites/rituals in various spheres of daily life, from the royal court down to individual households, were not just an outer performance of virtue, but they were believed to lead directly to the emergence of virtue in all parts of society, so that "rites" and "virtue" had practically the same meaning until the end of the Spring and Autumn period 春秋 (770-5th cent. BCE) (Wang 2016: 27).
The term li 禮, usually translated as "ritual" or "propriety", was the most important instrument of the Zhou to "maintain the state, carry out the governmental orders, and not to lose the people" (shou qi guo, xing qi zhengling, wu shi qi min 守其國，行其政令，無失其民, Zuozhuan 左傳; Zhaogong 5 昭公), or to "bring order into the state/the dynastic lineages, give settlement to the state altars of soil and grain, secure the order of the people, and to provide for the good of one's future heirs" (jing guo jia, ding sheji, xu renmin, li housi zhe 經國家，定社稷，序人民，利後嗣者; Zuozhuan, Yingong 隱公 11) (Li 1994: 108).
Li was thus a political attitude, and not just a set of social and religious ceremonies (yi 儀). The connection between such a political order with the spiritual world can be seen in the origin of the character 禮, which originally denoted a sacrificial vessel (醴) with which wine was offered to the spirits. Such a tie between offerings to a single non-ancestral spirits (Heaven) and politics was a novelty.
Rituals were expressed in the palatial architecture (with clear-cut division of, but close interaction between private and public spheres) or in the arrangement of tombs (with differences between ranks of the nobility expressed by the number of ritual vessels, lieding 列鼎, or in the construction of inner and outer coffin). In the lineage system (zongfa 宗法) of the Zhou, each member had a well-defined place in the ancestral temple according to his status in kinship. Transgression of these rules (jianyue 僭越) was not allowed.
Social rituals made a difference between "close" kinsmen (qin 親) that "approached" (qin as a verb) each other, and non-kinsmen which were to be treated with respect (zun 尊). The former were treated with kindheartedness (ren 仁), while the latter were to be dealt with in the framework of propriety (yi 義, "how to behave in a certain status and in a certain context"). The relation between father and son was therefore the basis on which the other private and public relations were built. The mother was to be respected just like the father was the head of the family, and a lord was to be "served" (shi 事) just like the own father deserved respect.
While the position of each member in a family or in society was fixed, the Zhou also believed that the kingdom was structured hierarchically, with the king at the top, and the rulers or the secondary or regional states (bangguo 邦國, fangguo 方國) in the various places of the kingdom, the minister and grand masters (qing dafu 卿大夫) servicing the central and local governments, and the servicemen (shi 士) institutions and villages. On the lowest level, the ground was also hierarchically divided according to a system later called the "well fields" (jingtianzhi 井田制).
The ritual system of the Zhou is said to have been introduced by the Duke of Zhou 周公, brother of the dynastic founder King Wu. The Duke was the paradigm for government according to the standards of "virtue". After the untimely death of his brother and the accession to the throne of young King Cheng 周成王, the Duke took over regency (shezheng 攝政) and acted as advisor or counsellor (xiang 相) of the sovereign. In this function he put down the rebellion of Guan Shu Xian 管叔鮮, defeated the eastern barbarians, and founded a secondary capital, Chengzhou 成周 (today's Luoyang 洛陽, Henan), in the east. When these questions of power were settled, he tackled the question of creating a coherent system of rituals, including ritual music (zhi li zuo yue 制禮作樂), and so created the "religio-social rules of the Zhou" (Zhouli 周禮, not the book Zhouli 周禮).
The Duke's rules fixed a hierarchical order for the royal house and the princely lineages, and joined this order with the right to dominate over landed estates. Each member of the royal house and of the nobility was given a certain status and was given land of a certain size to live off. This lineage system included the right of throne succession which lay with the oldest son, and not any more with a younger or older brother of the late sovereign, as under the Shang. The religio-social rules are found in the chapter Wangzhi 王制 "Royal Regulations" in the ritual classic Liji.
The cosmology of the Zhou operated with the belief in the "Five Agents" (wuxing 五行), sometimes called "Five Elements", but the translation "elements" is not appropriate because they represent statuses of natural forces, not "species of atoms" in the chemical sense or that of Greek Pre-Socratic philosophy (fire, earth, water, air).
Fragments in the book Shangshu dazhuan 尚書大傳, ch. Hongfan 鴻笵, a source from the very early Western Zhou, explain that the basis of the people's livelihood were fire and water (for eating and drinking), metal and wood (for living), as well as the soil (generating produce). Each of the Five Agents was not only associated with a human activity, but also with one of the five senses. The chapter Hongfan 洪範 in the transmitted Classic Shangshu adds some more correlations of the Five Agents, like their powers to transform, and the tastes which which they are related.
|水火者、百姓之所飲食也，金木者、百姓之所興作也，土者、萬物之所資生也。是為人用。||Water and fire is that from which the people live; metal and wood serve the people to flourish and to create [objects]; and earth is the source from which the ten thousand being arise. All this is useful for mankind. (Shangshu dazhuan, ch. Hongfan)|
|皃屬木，言屬金，視屬火，聽屬水，思屬土。火發于密，水洩于深。||Appearance is a matter of the agent wood, language that of metal, vision that of fire, hearing that of water, and thought is a matter of the agent soil. Fire arouses from density, and water emerges from the depth. (idem)|
|水曰潤下，火曰炎上，木曰曲直，金曰從革，土爰稼穡。||[The nature of] water is to soak and descend; of fire, to blaze and ascend; of wood, to be crooked and straight; of metal, to yield and change; while [that of] earth is seen in seed-sowing and in-gathering. (Shangshu, ch. Hongfan, transl. Legge 1865)|
|潤下作鹹，炎上作苦，曲直作酸，從革作辛，稼穡作甘。||That which soaks and descends becomes salt; that which blazes and ascends becomes bitter; that which is crooked and straight becomes sour; that which yields and changes becomes acrid; and from seed-sowing and in-gathering comes sweetness. (idem)|
The sequence, nature, and application of the Five Agents is described in these phrases. The agents are seen as a matter of change in the course of conflicts in nature. The right use of these agents under certain circumstances can prove useful, as seen in the story of the mythological emperor Yu the Great 大禹, who applied the nature of water and earth to tame the floods of the rivers.
Some of the agents were counterparts to each other, like down-running water und upwards-blazing fire, crooked wood and straight metal. The agents were able to devour or "defeat" (ke 克, sheng 勝) each other, like earth which soaks up water, or fire which extinguishes wood, etc., and are able to "produce" (sheng 生) each other, like water which gives life to wood, wood which helps to extract metal from ores, etc.
The authenticity of the Hongfan chapter in the Classic Shangshu cannot be proved, so that the earliest text which the relation between the Five Agents and government is described is the chapter Zhengyu 鄭語 in the history book Guoyu 國語. It is said the "former kings" (xianwang 先王) used the agent earth and combined it with metal, wood, fire, and water, to create the "hundred things" (cheng bai wu 成百物). While some scholars interpret this sentence as a kind of "creation of the world", others bring it into relation with craftsmen working under the royal court and producing various tools and objects by using the "five materials" (wucai 五材) (Du, Jin 2003: 114).
Another aspect of Zhou thought was binary thinking, i.e. the belief the existence of opposites, like fortune and misfortune (ji xiong 吉凶), prosperity and disaster (fu huo 福禍), great and small (da xiao 大小), hard and soft (gang rou 剛柔), top and bottom (shang xia 上下), inner and outer (nei wai 內外), advance and retreat (jin tui 進退), obtain and loose (de sang 得喪), living and dying (sheng si 生死), great and little (tai pi 泰否), increase and decrease (yi sun 益損), etc.
The paradigm of opposites is the duality of Yin and Yang - later expressed in the famous disk on which Yang 陽, the white area, diminishes when it has reached its largest extension, while the black Yin 陰 area gradually increases. This gradual model of growth and decline was perhaps influenced by the observation of the waxing and waning of the moon, and the change of the seasons.
Another origin of the Yin-Yang theory is the observation that those parts of the landscape which are illuminated by the sun (southern slope of a hill, northern slope of a river flowing west-east) are warmer and produce more plants than those not reached by the sun (northern slope of a hill, southern banks of a river). The word yang 陽 originally meant "place warmed by sunrays, sunshine", and yin 陰 "thickets, shadowy place" (like the word yin 隱). Around the year 1,000 BCE, these words were transferred to a more abstract realm and were used to identify two different aspects of nature, symbolized by the solid and broken lines of the trigrams and hexagrams of divination (see the "Changes"). But his is only one application of Yin-Yang thought.
The other way of applying the belief in Yin and Yang into administrative life was the identification of Yin with winter and Yang with summer, both expressed by the various elements of phenology changing over the course of the seasons. As the book Guoyu (ch. Zhouyu 周語 1) explains that in old times, the Grand Astrologer had not just observed the sky, but also soil and vegetation, to see whether the forces or energies (qi 氣) of Yin and Yang were mutually developing and retreating in accordance with the year. The administrative jurisdictions of the astrologer/astronomer and that of the Minister of agriculture (ji 稷) were overlapping (Du, Jin 2003: 113-114).
The forces of Yin and Yang might under certain circumstances – when their "order was transgressed" (guo qi xu 過其序) - be contained and their evolvement obstructed, and in this case, earthquakes would arise, the people brought into disorder, and a state would perish. The normal agent was that the forces of Yang had to rise, and those of Yin to sink down. Such was the theory in the late Western Zhou period (Du, Jin 2003: 114).
The Shang were famous for their divination with the help of heated cavities in bones, but transmitted sources speak of a hexagram system once used by the Shang (Guicang 歸藏), of which not much is known. The creation of the Zhouyi hexagrams is attributed to King Wen of the Zhou, or even to the mythological emperor Fu Xi 伏羲, but both ideas are rather hard to believe.
The hexagram system uses not only a binary model, meaning either one status, or its opposite, but also includes the belief that the change from one status to the other occurs by gradual increase of one status, until it reaches its extreme (ji 極) and then flips to other side, but back to the lowest level, like a trigger graph on an oscilloscope, as expressed in the proverb "when [hexagram] Little reaches its extreme, [hexagram] Great proceeds" (Pi ji Tai lai 否極泰來).
Apart from constituting opposites per se, there was the belief that under certain circumstances, one state could transform into its opposite. Divination about such transformations was performed with the help of trigrams (gua 卦) and hexagrams (chonggua 重卦) which are composed of three, or six lines, respectively, which can be either solid (━), or broken (╍). A change in status is expressed by the replacement of a broken line by a solid one, and vice versa. A handbook describing these changes is the Classic Yijing 易經 "Book of Changes", whose core part is also called Zhouyi 周易 "Changes of the Zhou". It includes 64 hexagrams which are created by milfoil divination (shi 筮) with the stalks of the milfoil plant (shi 蓍).
|☰||乾||Qian||the Creative||天 tian||Heaven|
|☷||坤||Kun||the Receptive||地 di||Earth|
|☵||坎||Kan||the Perilous Pit||水 shui||Water|
|☲||離||Li||the Clinging||火 huo||Fire|
|☳||震||Zhen||Exciting Power||雷 lei||Thunder|
|☶||艮||Gen||Arresting Movement||山 shan||Mountain|
|☴||巽||Xun||Gentle Penetration||風 feng||Wind|
|☱||兌||Dui||Joy and Pleasure||澤 ze||Swamp|
The eight trigrams consist of four pairs of opposites, namely Heaven and Earth, thunder and wind, water and fire, and mountain and lakes. The 64 hexagrams, combined permutations of the Eight Trigrams, likewise constitute, in their great number.
The Zhou people used to count out two hexagrams to answer their questions, just like the Shang, who had posed a question in a positive and in a negative form (like "will there be rain?", "will there not be rain?"). The second hexagram would show the Zhou people like the status of the first might change because of inherent inconsistencies. Such reasons for change were, for instance, the position of a trigram contrary to the natural position of the elements, like Earth above Heaven in the hexagram Tai 泰 ䷊. Yet Heaven below meant that its energetic vapours (qi 氣) were ascending and merging with the descending vapours of the earth. The mixture of the two vapours would benefit all creatures.
The hexagram Pi 否 ䷋ shows Heaven on the top and the Earth below, so that their vapours were separating from each other, and not benefitting nature. Yet with a change of the hexagram lines, Pi would transform into Tai, and so bring prosperity. The function of the hexgrams pairs Jiji 既濟 ䷾ and Weiji 未濟 ䷿, with fire and water, and other hexagrams in which yang symbols and yin symbols were either located above or below (Tongren 同人 ䷌/Dayou 大有 ䷍, Xun 巽 ䷸/Daxu 大畜 ䷙, Lü 履 ䷉/Guai 夬 ䷪), was similar. In all these cases, opposites belonged to each other and transformed to each other, so that positions of seeming contradiction might be profitable.
Each thing on earth was subject to constant change, and therefore each of the hexagram lines (yao 爻) had to be interpreted as a changing state. The hexagram Qian 乾 ䷀, for instance, describes how the auspicious animal dragon is rising from its hiding place in the well and ascending to the sky, where it "exceeds the proper limits, with the occasion for repentance" (kang long, you hui 亢龍，有悔) The hexagram Qian transforms into its opposite, Kun 坤 ䷁, which begins with hoarfrost and end with dragons fighting in the wild, their blood being dark and yellow, signifying the end of the progress of Kun (long zhan yu ye, qi xue xuanhuang 龍戰於野，其血玄黃).
In many hexagrams, the "change arises from minuscule things" (bian qi yu wei 變起於微) and occurs "when the extreme stage is reached" (wu ji bi fan 物極必反).
The set of 64 hexagrams is able to describe and understand the whole cosmos. The commentary Xici 繫辭 says: "Yes, wide is the Yi and great! [...] If we speak of it in connexion with all between Heaven and Earth, it embraces all.".
Hexagram Gen 艮 ䷳ says that it is necessary to gain an overview of a whole thing, instead of just a glimpse at a detail. Solid and broken lines (yanyao 陽爻, yinyao 陰爻) and numbers (6, 9) are used to express the presence of Yin and Yang in nature. A paradigm of numerology is the sentence in the commentary Xici explaining the "Great Expansion":
|大衍之數五十，其用四十有九。分而為二以象兩，掛一以象三，揲之以四以象四時，歸奇于扐以象閏。五嵗再閏，故再扐而後掛。||The numbers of the Great Expansion, [multiplied together], make 50, of which [only] 49 are used [in divination]. [The stalks representing these] are divided into two heaps to represent the two [emblematic lines, or Heaven and Earth]. One is then taken [from the heap on the right], and placed [between the little finger of the left hand and the next], that there may thus be symbolised the three [powers of Heaven, Earth, and man]. [The heaps on both sides] are manipulated by fours to represent the four seasons; and then the remainders are returned, and placed [between] the two middle fingers of the left hand, to represent the intercalary month. In five years, there are two intercalations, and therefore there are two operations; and afterwards the whole process is repeated.|
Jing Fang 京房 (77-37 BCE) interpreted the figure 50 as the sum of the days of the ten-day week (xun 旬), the twelve double-hours of the day (shi'er chen 十二辰), and the twenty- eight constellations (ershiba xiu 二十八宿). Ma Rong 馬融 (79-166 CE) added the "extreme dimension" (taiji 太極, everything inside the cosmos seen as one single unit) of the world's origin, the "two appearances" (liang yi 两儀; i.e. Yin and Yang), sun and moon, the four seasons, the Five Proceeses, the twelve months, and the twenty-four "energies" (ershisi qi 二十四氣), to reach 50. The great interpreter of the Classics, Zheng Xuan 鄭玄 (127-200), subtracted the number of the Five Agents from the "numbers of Heaven and Earth" (tian di zhi shu 天地之數, i.e. the sum of Celestial numbers 1, 3, 5, 7, 9, and of Terrestrial numbers 2, 4, 6, 8, 10), which was 55. The subtraction was justified by the fact that the energy of the Five Agents penetrated everything (wu xing tong qi 五行通氣). Xun Shuang 荀爽 (128-190) interpretes the number 50 as the product of six hexagram lines (yao) and the eight trigrams (gua), plus the important hexagrams Qian and Kun, in which the solid and the broken line, respectively, appear six times.
Much later, during the Song period 宋 (960-1279), the numerologist and early Neo-Confucian Shao Yong 邵雍 (1011-1077) sees fifty just as the double of the celestial numbers (tianshu 天數, i.e. 1+3+5+7+9=25). Master Zhu Xi 朱熹 (1130-1200) has again a very different approach by using the image of the River Chart (hetu 河圖), in whose centre 5 white dots represents Heaven, and 10 (divided into two lines of 5 black dots) the earth. Their product is 50. Hang Xinzhai 杭辛齋 (1869-1924), a late Qing-period 清 (1644-1911) scholar, sees in 50 the sum of the three square numbers 9, 16, and 25. The most recent interpretation came from Jin Jingfang 金景芳 (1902-2001), who was of the opinion that ancient books just left of the last cipher of the word fifty-five (Zheng Xuan's sum).
Experts discern between hexagram divination (shifa 筮法) with four "images" (sixiang 四象) and an older one with six "images" (liuxiang 六象). Both systems operate with the numbers six and nine to discern changeable Yin and Yang hexagram lines (bianyao 變爻). Liu Xinying 劉林鷹, a modern scholar of Yijing Studies (yixue 易學) holds that the combination of the "four images" with the two forces Yin and Yang (eryi 二儀) in the Yijing hailed from the ancient six-image divination.
Liu believes that the six images originated in the shape of gnomons (gui 圭, as can be seen in the character for "trigram", 卦, i.e. gnomon 圭 plus divination 卜) used for astronomical observations. The number of six images (trigrams) was later expanded to eight, by adding the trigrams Kan 坎 ☵ and Li 離 ☲. The original number of six can be seen in several theoretical combinations like "three Yin and three Yang" (sanyang sanyin 三陰三陽, i.e. Zhen 震 or shaoyang 少陽, Dui 兑 or yangming 陽明, Qian 乾 or laoyang 老陽, Xun 巽 or shaoyin 少陰, Gen 艮 or queyin 厥陰, and Kun 坤 or laoyin 老陰) used in theoretical medicine. The number of eight, as used in Zhou-period divination, was sanctioned by the belief – described in the Xici Commentary – that the Changes substantialized by the emergence of the two forces Yin and Yang out of the originary "extreme dimension" (taiji). Yin and Yang in turn produced the "four images" (standing for the seasons?), and the latter the Eight Trigrams.