The Explanations of the Sixty-Four Hexagrams by King Wen - The Lectures on the Sacred Classics by the Sage Confucius

六十四卦，自八卦出，無論伏羲文王一也；其次序自伏羲八卦方位定，無論先後天一也。唯六十四卦，有本宮次序，有本卦次序，有相錯次序，有相和次序，各以其變化而定。本宮者，分乾坎艮震巽離坤兌八宮，各八變，成六十四卦，此序卦之自生也。

All sixty-four hexagrams are derived from the eight trigrams. Whether it is the Yi of Fuxi or the Yi of King Wen, there is no difference in this regard; their order also depends on the arrangement of the eight trigrams of Fuxi, whether earlier Heaven or later Heaven, and this is also without difference. However, the arrangement of the sixty-four hexagrams has several systems: there is the "order within the palace," the "order of the primary hexagram," the "order of mutual opposition," and the "order of mutual harmony," each determined by the particular method of change adopted. The "order within the palace" divides the sixty-four hexagrams into eight palaces: Qian, Kan, Gen, Zhen, Xun, Li, Kun, and Dui. Each palace undergoes eight changes, resulting in the sixty-four hexagrams. This is a method of arrangement that arises naturally from the hexagrams themselves.

本卦者，亦依八卦之生化，而以乾兌震離巽坎艮坤之序，分屬一卦，以成八屬，此明卦氣之消長為循環也。相錯者，以卦之交錯，分乾坤坎離震艮巽兌，相交錯而成行，以循環而為序，即《周易》上下經之序也。

The order of the primary hexagrams is also arranged according to the generation and transformation of the eight trigrams. Following the sequence of Qian, Dui, Zhen, Li, Xun, Kan, Gen, and Kun, all hexagrams generated from a particular trigram are grouped under that trigram's name, forming eight categories. This is used to explain the continuous cycle of the hexagram energies. The sequence of alternating trigrams is determined by the mutual crossing of trigrams. The trigrams Qian, Kun, Kan, Li, Zhen, Gen, Xun, and Dui are separated and arranged alternately in rows. The order is determined by the cyclic pattern, which establishes the sequence of the upper and lower parts of the Zhou Changes.

相和者，亦卦之交錯，合其體用，明其常變，和先後天之例，一伏羲文王之序，並及《連山》《歸藏》之成規，與本宮本卦參照而為序者，即《雜卦傳》之序也。蓋卦變本多，變必有例，易以明變，則一變有一序也。以此四者舉其凡，若盡其變，尚不止耳。

The concept of harmony and sequence also involves the intermingling of hexagrams, but it goes further by combining the essence and function together, clearly indicating both the constant principles and the changes. It harmonizes the Earlier Heaven and Later Heaven systems, unifies the two arrangements of Fuxi and King Wen, and takes into account the old practices of the books of Continuous Mountains and Returning Concealment. It also refers to the sequences of the original palace and the primary hexagram to determine the order. This is the order used in the "Zagua Transmission." Generally speaking, hexagrams naturally have many variations; whenever there is change, there must be a corresponding system. The Book of Changes is precisely used to explain change, so each variation produces a different pattern, and thus there is a corresponding order. Here four examples are given only as a general idea; if all variations are to be fully covered, there would be more than these.

六十四卦既由八卦出，八卦之序已有不同，則六十四卦之序，自分多類。不過後天易象重在交錯，二五流行，無不交互，天下萬類無非錯行，合則以生，分則以化，推之不盡，用之不窮，則當以文王所序之例為主，以能象現在之事物，而可推諸往來之氣數也。其它各例，以備參考，俾知序變則用殊，易道不窮，則變例無盡。

The sixty-four hexagrams arise from the eight trigrams, and since the eight trigrams themselves have an order of Earlier Heaven and Later Heaven, the order of the sixty-four hexagrams naturally divides into many categories. However, the Later Heaven arrangement of the Book of Changes focuses on intermingling: the energies of yin and yang and the five phases constantly flow and interact everywhere, and all things under heaven are intermingled. When combined, they give rise to existence; when separated, they undergo transformation. This process continues endlessly, and its application is inexhaustible. Therefore, we should take the system established by King Wen as the main reference, because it can symbolize current realities and be used to calculate the flow of energies. Other systems should be left as references, so that people may understand that when the order changes, its function also changes. The Way of the Book of Changes is boundless, and so too are the systems of change.

有後聖者出，推而廣之，亦足與文王易同，則變例之存，將有待於推闡，不獨溯源探本已也。文王所定六十四卦次序，大別之為上下篇，而上篇統於乾坤坎離，下篇統於震艮巽兌，此大略也。其實皆相錯交互，明氣之周流，二氣消息往復無已，自為環行，繫後天自然之象。

If there were a sage in later generations who could elaborate and expand upon these systems, they would be sufficient to stand equal with the Yi of King Wen. This shows that preserving these variations is left for later scholars to explore and clarify, not merely for tracing back to the origin. The order of the sixty-four hexagrams established by King Wen is generally divided into upper and lower parts: the upper part belongs to Qian, Kun, Kan, and Li, while the lower part belongs to Zhen, Gen, Xun, and Dui. This is a general classification. In reality, both upper and lower parts are interwoven and contain each other, used to illustrate the continuous flow of qi. The mutual rise and fall, movement and return of yin and yang energies have no end, naturally forming a circular movement, which is precisely the natural phenomenon of the Later Heaven.

由先天既變，氣隨形化，數隨事見，天道存於人物，化育寓於時位，皆莫為而為，莫致而至，以繼往啟來，垂今鑑古，無不符合，故為易之主體，而見卦之大用也。上篇三十，首乾坤而終坎離，明先後天之卦象異主，坎離即以代乾坤，為宇宙之樞機，運陰陽之中極，而天地間萬物從此生化也。

Since the Earlier Heaven transformed into the Later Heaven, the vital energy has changed along with forms, and numbers have manifested along with things. The heavenly way resides within people and objects, and the nurturing and transformation are contained within seasons and directions. All of this happens naturally without deliberate effort, without intentional invocation, and naturally comes to be. It connects the past with the future, guides the present, and reflects upon the ancients, with nothing failing to correspond. Therefore, the sequence established by King Wen became the main body of the Book of Changes, and the great function of the hexagrams is thus evident. The upper section contains thirty hexagrams, beginning with Qian and Kun and ending with Kan and Li, clearly indicating that the rulers of the Earlier Heaven and Later Heaven hexagram systems have changed: Kan and Li have replaced Qian and Kun, becoming the key elements of the universe, operating at the center of yin and yang, and from here all things in the universe between heaven and earth begin to grow and flourish.

下篇首咸怛，終既未濟，即本上篇乾坤坎離交錯，而成人類之萬事萬象，以震艮巽兌縱橫其間，明事物之迴環曲折，無窮無盡。人主其中，以代天地，並化育，為世界開化，為物類建極，以成天地人三才之德，而全易卦六爻之用。此下篇三十四卦始終，與上篇大同，皆以乾坤起，坎離終，而更交錯之也。

The lower section begins with the hexagrams "Xian" and "Heng" (the latter originally written as "Da"), and ends with "Ji Ji" and "Wei Ji." This structure continues from the interweaving of Qian and Kun, Kan and Li in the upper section, thereby forming the myriad phenomena of the human world. Then the hexagrams Zhen, Gen, Xun, and Dui are interwoven throughout to illustrate the endless cycles and twists of things. Humans dwell amidst all these, taking the role of heaven and earth, participating in the process of nurturing and transforming all things. They bring civilization to the world and establish standards for all creatures, thus achieving the virtue of the three elements—Heaven, Earth, and Humanity. This also completes the full function of the sixty-four hexagrams. The overall structure of the thirty-four hexagrams in the lower section is similar to that of the upper section, both beginning with Qian and Kun and ending with Kan and Li, but the interweaving is more complex.

蓋後天之象異先天者，以多變也。變因於交錯，而天地既判，人物已繁，往來其中者，形與氣也。司形者數，司氣者神；神主於隱，數行於顯，於是一者分為二矣。先天一氣，同屬乾坤，雖二仍一，以氣同也；後天之變，乾坤分居，坎離代用，形氣並具，二者乃分。

Later Heaven differs from Earlier Heaven, primarily because of the multiplicity of change. Change arises from interaction, and once heaven and earth have been separated, human beings and things have become numerous. What moves among them is no more than the two aspects of "form" and "vital energy." The aspect of form is governed by numbers, while the aspect of vital energy is governed by spirit; spirit resides in the subtle and hidden, while numbers operate in the manifest and clear. Thus, what was originally unified splits into two. Earlier Heaven consists of a single vital energy, unified under the governance of Qian and Kun, though it is said to be two trigrams, they are still one in essence, because they share the same vital energy. After the change of Later Heaven, Qian and Kun retreat to the four corners and occupy two positions, while Kan and Li take over their functions. Form and vital energy coexist, and thus the division into two is truly established.

故後天統於水火，分於木金，而同寓於土，非復先天二氣之一源，生化盡於乾坤，周迴歸於陰陽，其象簡，其數單，而明顯易見，純一易名也。故後天之卦，必以交錯為用，愈交愈生，愈錯愈化，生化日眾，交錯益多。此六十四卦，雖大類統於水火，屬於四正，而其往復之跡、消息之機，無不縱橫如織，迴環若輪也。此文王六十四卦定序之義也。

Therefore, the Later Heaven system is governed by water and fire, distributed among wood and metal, and jointly resides in earth. It is no longer like the Earlier Heaven, where yin and yang arise from the same source, and all processes of generation and transformation belong to Heaven and Earth, circulating in a cycle and returning to yin and yang. The image of the Earlier Heaven is simple, with a small number of elements, clearly visible, purely unified, and easy to name. The hexagrams of the Later Heaven, however, must be used through their interweaving: the more they intersect, the more things they generate; the more they differ, the more transformations they produce. The processes of generation and transformation increase day by day, and the intersections become more intricate day by day. Therefore, these sixty-four hexagrams, although generally categorized under water and fire and belonging to the four cardinal directions, their reciprocal movements and the mechanisms of their waxing and waning are all like the crossing threads of a loom, or the turning of a wheel. This is the intention of King Wen in establishing the order of the sixty-four hexagrams.

文王六十四卦次序，雖因交錯，而因異本宮本卦之序，而其取法者，則仍乾坤對列之八卦位次也。蓋乾坤對列之位次，雖屬先天卦象，究為卦象本體，不得棄之而別取法也。若上離下坎之象，雖名後天位次，其為用祇與本宮本卦之序相證，而非文王六十四卦序所本也。

King Wen's sequence of the sixty-four hexagrams, although different from the sequences of the original trigrams and the primary hexagram due to the principle of mutual crossing, still follows the fundamental arrangement of Heaven above and Earth below, with the eight trigrams paired accordingly. Although the arrangement of Heaven above and Earth below belongs to the Earlier Heaven diagram, it is the essential position of the trigrams and cannot be abandoned for another basis. As for the diagram with Fire above and Water below, although it is called the Later Heaven arrangement, its function is only to corroborate the sequences of the original trigrams and the primary hexagram, and it is not the fundamental basis for the sequence of the sixty-four hexagrams. In other words, King Wen changed the positions of the eight trigrams, but in the sixty-four hexagrams he returned to the fundamental principle of Heaven above and Earth below. The positions can change with time, but the essential nature cannot change along with the positions, otherwise change would lose its reference point, and the mutual crossing and arrangement of the sixty-four hexagrams would be impossible.

此其異者，以先天之至後天，因其變，變有其例，因於體用，體此而用則彼，體先而用則後。文王八卦位次，仿自伏羲八卦，而與本宮本卦之序相應，一先一後，一體一用也。二者同出異用，一常一變，常者不變，故其用能變，變而不失其常。若體已變，則何以用變？以變為變，將不復知有常矣，則易道亂，亂則何以神其用哉？故變者本於不變，而後天必本於先天也。

The difference between them arises because moving from the Earlier Heaven to the Later Heaven necessarily involves a transformation, and this transformation follows a specific pattern, which depends on the relationship between form and function: taking one set as form, another set becomes function; taking the Earlier Heaven as form, the Later Heaven becomes function. The arrangement of King Wen's eight trigrams is modeled after Fuxi's eight trigrams, and it corresponds with the sequence of the original trigrams and the primary hexagram, one preceding the other, one as form and one as function. Both originate from the same source but serve different purposes; one is constant, the other is changeable. The constant aspect remains unchanged, so the changeable aspect can change; even though it changes, it does not lose its constancy. If the original form itself were to change, then what would the function rely on to change? Changing by means of change would lose the constant, and the Way of the Book of Changes would become chaotic; once it is chaotic, how could its function become profound and mysterious? Therefore, change must be based on constancy, and the Later Heaven must be based on the Earlier Heaven.

世之習易者，以文王六十四卦不合其八卦位次，而其八卦位次恰與本宮之序同，有疑為不如是者。不知六十四卦者，全易之象，八卦亦在其中；文王六十四卦之序，即後天之象，與伏羲本宮卦序，正為體應，非可疑也。苟就六十四卦之象前後觀之，其氣消息，其數盈虛，其行往復，其道迴環，無不與伏羲八卦位次同，蓋可見其取法所自矣。

People who study the Book of Changes in the world notice that the arrangement of the sixty-four hexagrams in King Wen's system does not match the order of the eight trigrams he himself established, but instead exactly corresponds to the sequence of the hexagrams in his own palace. Therefore, they doubt that this should be the case. They do not realize that the sixty-four hexagrams encompass all the images of the Book of Changes, and the eight trigrams are already included within them. The sequence of the sixty-four hexagrams in King Wen's system is precisely the Later Heaven arrangement. It has a relationship of essence and response with the original sequence of the eight trigrams from Fuxi. There is nothing to doubt. If one carefully examines the sequence of the sixty-four hexagrams from beginning to end, one will find that the flow of energy, the waxing and waning of numbers, the movement back and forth, and the circular path all correspond exactly with the positions of the eight trigrams from Fuxi. The source of this system becomes clearly evident.

且六十四卦之序，不有數例在乎？試各按之，皆足以參證其用。以本宮言之，三變而後則屬對宮，七變為游魂，八變為歸魂，仍本先天八卦方位者也。蓋變多必因交錯，氣交數錯，變乃無盡。後天以變為主，固必取交錯之例。交錯以對位為主，以旁行為輔；對位為交，旁行為錯。如乾之坤，對位也；之離坎，則旁行也。

Moreover, the order of the sixty-four hexagrams is not based on just one system; there are several different arrangements. If each is tested individually, each is sufficient to confirm its function. In terms of the sequence of this particular palace: after the third change, it moves to the opposite palace; the seventh change is called "you hun" (wandering soul), and the eighth change is called "gui hun" (returning soul). This still follows the positional arrangement of the Earlier Heaven Trigrams. The reason for the multitude of changes is due to the interweaving: when the qi (vital force) meets and the numbers shift, the changes have no end. The Later Heaven focuses on change, so it must adopt the system of interweaving. Interweaving is mainly based on "duiwei" (opposite position) and assisted by "pangxing" (side movement): "duiwei" is called "jiao" (meeting), and "pangxing" is called "cuo" (error). For example, moving from Qian to Kun is "duiwei"; moving from Qian to Li or Kan is "pangxing".

文王六十四卦序，其例正如此，故以乾坤為首，以既未濟為終，明後天之交錯，而象事物之生化也。夫本宮之序，終於歸妹，與此之終於未濟，其義亦可互參。傳曰歸妹女之終也，未濟男之窮也。乾道成男，坤道成女，男女即乾坤也，乾坤即天地也，天地即陰陽也。陰盡于歸妹，明體靜也；陽盡於未濟，明用動也。

King Wen's arrangement of the sixty-four hexagrams follows this system, beginning with the hexagrams Qian and Kun and ending with Ji Ji and Wei Ji, to illustrate the Later Heaven arrangement and symbolize the growth and transformation of things. The sequence of this particular set of hexagrams ends with Gui Mei, which can be cross-referenced with King Wen's sequence ending with Wei Ji. The "Xugua Zhuan" states, "Gui Mei signifies the end of women," and "Wei Ji signifies the end of men." The "Xici Shang Wen" says, "The way of Qian gives rise to masculinity, and the way of Kun gives rise to femininity." This shows that male and female correspond to Qian and Kun, Qian and Kun correspond to heaven and earth, and heaven and earth correspond to yin and yang. The termination of yin energy at Gui Mei indicates the principle of stillness, while the termination of yang energy at Wei Ji indicates the principle of action.

先天主靜，內陽外陰；後天主動，內陰外陽。故文王之序，以乾始，以未濟終，示陽氣之循環，為後天生化之本；而陽氣之終盡，為人物窮竭之時。此其取義，亦象天地自然之氣者也。況易者盡而無盡，窮而復通，以其循環也。天地為一大循環，終則有始，非不續也，故未濟窮而不窮。

The Earlier Heaven emphasizes stillness, with yang within and yin outside; the Later Heaven emphasizes movement, with yin within and yang outside. Therefore, King Wen's arrangement starts with the Qian hexagram and ends with the Weiji hexagram, illustrating that the cycle of yang energy is the fundamental principle of later heaven generation and transformation. When yang energy reaches its limit, it is also the time when both people and things reach their exhaustion. This meaning is also a depiction of the natural flow of qi in heaven and earth. Moreover, the Yi Jing discusses completeness that is not yet complete, and exhaustion that is not final, because it is inherently cyclical. Heaven and earth form a great cycle; reaching the end is also the beginning again, and it is not a complete interruption. Thus, although Weiji is named as the extreme, in reality it is not truly extreme.

卦象先後天之異，在方位與次序，夫子已詳言之。唯先後天各圖象，位次各不同者，以其氣數各有合也。伏羲八卦位序，為一切根本，其六十四卦則有數種；位序不同，名類斯異。文王八卦位序，自伏羲變來，其六十四卦，亦與伏羲者殊，然皆出於上乾下坤之八卦位序則同。蓋根本一，而變化無盡也。

The differences between the Earlier Heaven and Later Heaven diagrams are reflected in both direction and sequence. The Master has already explained this in detail. However, the reasons why the various diagrams of Earlier Heaven and Later Heaven differ in their positions and order are due to the different ways in which their energies and numbers are combined. The sequence of the Eight Trigrams of Fuxi is the foundation of all Yi diagrams. From this, sixty-four hexagrams can be derived, but there are several different arrangements. If the sequence differs, the names and classifications also change accordingly. The sequence of the Eight Trigrams of King Wen is derived from that of Fuxi. The sixty-four hexagrams derived from King Wen's sequence also differ from those of Fuxi. However, in the end, they all originate from the same fundamental sequence of Heaven above and Earth below in the Eight Trigrams. There is only one root, yet the variations arising from it are endless.

伏羲六十四卦，應以本卦之序為最明顯，即依乾、兌、離、震、巽、坎、艮、坤之一、二、三、四、五、六、七、八次序，而將本卦所變者，統屬之於一卦。如乾卦之下，兌乾、離乾、震乾、巽乾、坎乾、艮乾、坤乾各卦，即夬、大有、大壯、小畜、需、大畜、泰，皆屬之乾卦。

Fu Xi's sixty-four hexagrams are most clearly ordered according to the sequence of the Primary Hexagram. This sequence follows the Earlier Heaven order: Qian (Heaven) one, Dui (Lake) two, Li (Fire) three, Zhen (Thunder) four, Xun (Wind) five, Kan (Water) six, Gen (Mountain) seven, and Kun (Earth) eight. All hexagrams generated from a particular Primary Hexagram are grouped under that one. For example, under the Qian hexagram, all hexagrams with Qian as the Lower Trigram and Dui, Li, Zhen, Xun, Kan, Gen, or Kun as the Upper Trigram—namely, Gua, Da You, Da Zhuang, Xiao Xu, Xu, Da Xu, and Tai—are grouped under Qian. This grouping is because the Lower Trigram represents the inner and primary aspect, and the Earlier Heaven system discusses the generation of qi. Qi arises from within and moves outward, from below to above. Therefore, the Lower Trigram determines which hexagram is generated. The change of the Upper Trigram merely indicates the different objects encountered by this qi. Each of the eight trigrams leads eight hexagrams, and eight multiplied by eight gives exactly sixty-four, neither more nor less.

其次則兌卦，兌所合者，如履、兌、暌、歸妹、中孚、節、損、臨各卦，皆屬之。兌以下，如離、如震、如巽、坎、艮、坤各本卦所合者，依序列之，以為全易次序。因其由本卦所推，故名為本卦序；因其依先天八卦位次，故名為先天六十四卦序，或伏羲六十四卦序。

The next is the Dui trigram. All hexagrams that combine with Dui, such as the hexagrams of "Lǚ" (Following), "Dui" (Joy), "Kuí" (Strife), "Guī Mèi" (Return of the Maiden), "Zhōng Fú" (Faith in the Middle), "Jié" (Regulation), "Sǔn" (Loss), and "Lín" (Approach), are all classified under Dui. Following Dui, the hexagrams generated by combining with Li (Fire), Zhen (Thunder), Xun (Wind), Kan (Water), Gen (Mountain), and Kun (Earth) are also arranged in the same manner, sequentially. Together, they form the entire sequence of the Book of Changes. Because these hexagrams are derived from the primary hexagrams, this sequence is called "Primary Hexagram Sequence." Additionally, since it follows the order of the Earlier Heaven Trigrams, it is also referred to as "Earlier Heaven Sixty-Four Hexagram Sequence" or "Fuxi Sixty-Four Hexagram Sequence."

此種卦序，為圖有方，有圓，有平列，有豎立，其象雖殊，致用略一，而其別於他類者，順八卦之位次，示本卦之分合，無交錯之用，純先天之象。蓋其變化少，而生育之功不見，藉以定天地之位、辨氣數之差而已。故後人多不曉其意義，不過備易象之一格，而為他卦參證云爾。

This set of hexagram sequences can be drawn in various forms, such as square diagrams, circular diagrams, flat arrangements, or vertical arrangements. Although the forms differ, their general purposes are similar. Its distinction from other methods of arrangement lies in the fact that it follows entirely the order of the eight trigrams, only showing how the primary hexagram is divided and combined, without discussing the interweaving between hexagrams. It is a pure representation of the Earlier Heaven pattern. Because it contains fewer changes, it is not capable of demonstrating the function of generating all things. It can only be used to determine the directions of heaven and earth and to distinguish differences in the vital energies. Therefore, later generations mostly did not understand its meaning, treating it as a mere part of the Yi hexagrams, used only for mutual verification with other hexagram sequences.

又有本宮卦序者，則依文王八卦位次，而為各類；其卦變化，則依本宮對宮相交錯，及比類五卦，而推生各卦，皆為八變。如乾宮自乾起，初變為乾巽，次為乾艮，次為乾坤，次為巽坤，次為艮坤，次為離坤四，終為離乾，即乾、姤、遯、否、觀、剝、晉、大有各卦，依次序列，屬之乾宮卦。

There is another system called "the sequence of the trigrams within their respective palaces," which divides the trigrams according to the order of the King Wen trigrams. As for the transformation of the trigrams, they are generated by the interaction between the trigram of the palace and the trigram of the opposite palace, along with adjacent trigrams of the same type, resulting in eight transformations for each palace. For example, the palace of Qian starts with the Qian trigram: the first transformation is upper Qian and lower Xun, the second is upper Qian and lower Gen, the third is upper Qian and lower Kun, the fourth is upper Xun and lower Kun, the fifth is upper Gen and lower Kun, the sixth is upper Li and lower Kun, and the last is upper Li and lower Qian. That is, the trigrams of Qian, Gou, Dun, Po, Guan, Bo, Jin, and Dàyǒu are arranged in order, all belonging to the palace of Qian.

其次為坎宮，自坎以下，為節、屯、既濟、革、豐、明夷、師各卦，亦依變化之次序列，屬之坎宮卦。以下如震、如巽、如離、如坤、如兌，皆依後天八卦位次序列，以推生全易卦象者也。以其變由生於本宮，不似前之出於本卦者，故名本宮卦序，亦曰八宮卦序，或稱後天六十四卦序。然非與文王六十四卦序同，不過序列各宮，依文王八卦位次，其推生變化純先天例，有異文王後天交錯之序也，應仍屬之先天卦序之一種。

Next is the Kan Palace: starting from the Kan hexagram, the sequence proceeds to the hexagrams 《Jie》, 《Zun》, 《Ji Ji》, 《Ge》, 《Feng》, 《Ming Yi》, and 《Shi》, arranged in the order of their transformation. All these hexagrams belong to the Kan Palace. Continuing downward, the Zhen Palace, Xun Palace, Li Palace, Kun Palace, and Dui Palace are also arranged according to the positions of the Later Heaven Trigrams, used to generate all the images of the sixty-four hexagrams. Since these transformations originate from within each palace, unlike the previous method which involves combining hexagrams, they are called "hexagram sequences within the palace," also known as "eight palace hexagram sequence" or "Later Heaven sixty-four hexagram sequence." However, it is not equivalent to the sequence of the sixty-four hexagrams arranged by King Wen. It merely arranges each palace in the order of the eight trigrams of King Wen. The principles used for generating and transforming the hexagrams are purely based on the Earlier Heaven system, differing from King Wen's Later Heaven arrangement which involves interweaving. Therefore, it should still be considered a type of Earlier Heaven hexagram sequence.

此種卦序，有一定之例，即自本宮本卦起，三變而至對宮，七變而為對比宮，是曰游魂；八變由比宮仍還本卦，是曰歸魂。大凡八卦，依伏羲方位相對者曰對宮，相併者曰比宮。如乾與坤，離與坎，震與巽，艮與兌，對宮也；如乾與離，坤與坎，震與艮，巽與兌，則比宮也。

This sequence of hexagrams follows a fixed pattern: starting from the primary hexagram of the original trigram, the transformation reaches the third change and moves to the opposite trigram's palace, then at the seventh change it moves to the palace adjacent to the opposite one, and this transformation is called "you hun." When it reaches the eighth change, it returns from the adjacent palace back to the original hexagram, and this transformation is called "gui hun." In general, among the eight trigrams, two trigrams that are opposite to each other according to Fuxi's arrangement are called "dui gong," while two trigrams that are adjacent to each other are called "bi gong." For example, Qian and Kun, Li and Kan, Zhen and Xun, Gen and Dui are dui gong; while Qian and Li, Kun and Kan, Zhen and Gen, Xun and Dui are bi gong.

對宮不獨本卦位次相對，其變化位次皆相對。如乾變之巽，之艮，至坤，由離返乾，皆自上下行，由下返上；而坤則之震，之兌，至乾，由坎返坤，皆自下上行，由上返下。所至所行，恰相對也。

The hexagrams in opposite trigrams not only have their positions relative to each other, but also the positions they pass through during transformation are oppositely aligned. For example, the transformation of the Qian trigram first reaches Xun, then Gen, and finally Kun, and finally returns to Qian via Li. This path follows a route from top to bottom and then back from bottom to top. Meanwhile, the transformation of the Kun trigram first reaches Zhen, then Dui, and finally Qian, and then returns to Kun via Kan. This path follows a route from bottom to top and then back from top to bottom. The destinations and the paths taken are exactly opposite to each other.

其行各宮，而生變化，一宮所涉者五，不入者三。如乾涉巽、艮、坤、離，坤則涉震、兌、乾、坎，餘宮皆然，此其例也。蓋氣之變，必以動，變至三則易其位，至七則遊於比宮，八則歸於本宗。故一宮八卦，所交五宮，亦自然變化之序。此序之用，為納甲所本，於占法適宜，是先天用法，古人常取之以卜筮，至今猶傳，與後天卦序有相闡發也。

Changes move among the various palaces, and each palace is connected to only five others, with three palaces unreachable. For example, the Qian palace relates to Xun, Gen, Kun, and Li; the Kun palace relates to Zhen, Dui, Qian, and Kan; the same applies to the other palaces. This is the general rule. Change requires movement: after the third change, the direction shifts; after the seventh change, it moves to an adjacent palace; after the eighth change, it returns to its original palace. Therefore, the eight trigrams of one palace relate to five other palaces, following the natural order of change. This sequence is fundamental to the method of 'Najia' stem assignment, which is very suitable for divination. It belongs to the Earlier Heaven system, and ancient people often used it for divination, and it has been passed down to the present day. It can be used in conjunction with the Later Heaven sequence to explain each other.

此外有合一歲序者，亦有數種。如以八卦八宮分候四季者，以乾坤二宮分候十二月者，以六十四卦分候全歲、一卦六日七分者，其例詳各家書，皆傳自古，為曆數家所用，亦本先天卦象，推其變化，而應於歲時，無不合也。

In addition, there are also various systems that combine the trigrams with the seasonal changes of a year. For example, some use the eight trigrams divided into eight palaces to correspond with the four seasons, others use the Qian and Kun palaces to correspond with the twelve months, and still others distribute the sixty-four hexagrams throughout the entire year, with each hexagram governing six days and seven parts. These systems are thoroughly recorded in the writings of different scholars, and they have been passed down since ancient times, adopted by those who study calendars and mathematics. They all base themselves on the Earlier Heaven trigrams, deduce their transformations, and use them to correspond with the seasonal changes of the year, and they all match perfectly.

蓋卦象包羅無盡，其變化隨用而見，初非限於一例也。天文地理，日月度數，星辰躔次，山川里程，人物形體，皆有所象。神而明之，無不符合，固不僅象一事一物，亦不止象一時一世。果推而廣之，則宇宙之圖，今古之跡，天下之事，神形之倫，在大氣之中者，無不隨象而可征也。蓋氣者生化之本源，卦象氣也，則凡有生化者，舉不外於卦象，而視人之能明否耳。

The infinite variations contained in the hexagrams are not limited to a particular system; they manifest according to their application. The hexagrams can correspond to astronomical and geographical phenomena, the degrees of the sun and moon's movement, the positions of stars, the distances of mountains and rivers, and the forms of people and objects. As long as one can understand and explain them thoroughly, there will be no discrepancy. The hexagrams do not merely symbolize specific things or events, nor do they represent particular times or eras. If we truly expand their application, then the entire universe, the records of past and present, the affairs of the world, and all kinds of beings and forms existing within this great atmosphere can all be verified through the hexagrams. This is because qi is the source of generation and transformation, and the hexagrams symbolize precisely this qi. Therefore, all things that undergo generation and transformation are encompassed within the hexagrams, and the only difference is whether people can comprehend them.

文王之易，亦此一例，以後天之卦，象後天之氣，而推及變化所至而已。故易象一，而用無盡；一者本也，即伏羲八卦是也，餘皆其用。而所異則在次序，次序異，則象異；而象不因事物名，皆以氣數紀。先天之氣純數簡，故取象少，既伏羲八卦，已足為萬變之宗；後天之氣交數繁，故取象眾。

The Yi of King Wen is also one of these systems: using the Later Heaven trigrams to symbolize the Later Heaven qi, then deriving the various changes that this qi brings about. That is all. Thus, the origin of the Yi images is one, yet its functions are endless—the "one" is the root, that is the trigrams of Fuxi. All other arrangements are merely its applications. The differences among various arrangements lie only in the order: when the order changes, the images taken also change. However, the images are not named according to specific things, but are uniformly recorded by qi and numbers. The qi of the Earlier Heaven is pure and the numbers simple, so the images taken are few; with just the trigrams of Fuxi, they are sufficient to serve as the master principle for all changes. The qi of the Later Heaven is complex and the numbers intricate, so the images taken are numerous.

雖匯各序例，猶未盡其變，但歧途而同歸，仍不離一本之源。此無論為伏羲，為文王，為連、歸，為本宮本卦，六日七分，歲時星紀，種種例用，更無問其為出自先天後天，合自八卦六十四卦，皆一也，皆上乾下坤之八卦位次，所生所化耳。故伏羲八卦，為一切卦之母，因得名先天之象，其餘皆後天也。

Even if all the various systems of arrangement are gathered together, they still cannot exhaust its transformations; however, all paths lead to the same origin. Therefore, whether it is the Yi of Fuxi or the Yi of King Wen, whether it is the Lianshan and Guicang, whether it is the order of the palace, the order of the primary hexagram, the method of six days and seven parts, or the method of coordinating with the seasons, stars, and the calendar, all these systems and methods, let alone the question of whether they come from the Earlier Heaven or the Later Heaven, or whether they are derived from the Eight Trigrams or the sixty-four hexagrams — they are all the same thing, all derived from and transformed from the arrangement of the Eight Trigrams with Heaven on top and Earth below. Therefore, the Eight Trigrams of Fuxi are the mother of all hexagrams, hence named "the image of the Earlier Heaven." The rest are all considered Later Heaven.

然以伏羲六十四卦本卦之序，與文王者異，亦名之先天，猶日後天之先天也。若繩之八卦，則為後天；若較之文王各卦，則為先天。故以此別之，其實先天之象祇一，而克稱先天者，上乾下坤之八卦序耳。此為爭論先後天之重要處，故表出之，以袪世人之惑。

However, the order of the sixty-four hexagrams in Fuxi's system is different from that of King Wen, so it is called Earlier Heaven. This is like saying it is "Earlier Heaven within Later Heaven." If we measure it by the source of the Eight Trigrams, it already belongs to Later Heaven; but if we compare it with King Wen's hexagrams, it is considered Earlier Heaven. People distinguish between them in this way. In reality, there is only one true image of Earlier Heaven, and only the sequence of the Eight Trigrams with Heaven on top and Earth below qualifies as Earlier Heaven. This is exactly the key point of contention throughout history regarding Earlier and Later Heaven, so it is specially pointed out to eliminate people's doubts.

文王六十四卦次序，所取旨意，已見序卦傳，而所應知者，則其例也。其次序本於伏羲八卦方位，以往來交錯而成，而其連接者，皆相對也。以後天生化，必一陰一陽，交互而行，非如先天之陽行於陽，陰行於陰也。故文王六十四卦，取八宮各卦，分合而交錯之，本八卦位次，往復而對舉之，以成一陰一陽之道，而見天生地成之義。

The rationale behind the order of the sixty-four hexagrams in the Book of Changes, as explained in the "Sequence of Hexagrams" passage, is already clarified. Readers should also be aware of the arrangement principle. This sequence is based on the original positions of the eight trigrams attributed to Fuxi. Through their mutual interaction and alternation, each pair of consecutive hexagrams are opposites of each other. Because the later heaven's generative process necessarily involves the alternation of yin and yang, unlike the earlier heaven where yang moves only within yang and yin moves only within yin. Therefore, the sixty-four hexagrams of King Wen are derived by taking the eight trigrams and either separating or combining them to create alternations. According to the order of the eight trigrams, they are paired alternately to illustrate the principle stated in the "Great Treatise Upper Transmission" that "yin and yang together are called the Dao," thereby demonstrating the meaning of heaven's giving birth and earth's forming things.

凡各卦之有往者，必繼之以復；有上者，必對之以下；有奇者，必聯之以偶；有動者，必應之以靜。使本宮對宮相錯，比卦類卦相交，不限於八宮之序，不囿於本卦之次；而其次序，恰與八宮相證，不亂其數；恰與本卦相通，不乖其位，以後天自然之序也。天地人物，歲時日月，周行不息，動靜有度，皆如此序。

Whenever there is a hexagram indicating movement outward, there must be a following hexagram indicating return; whenever there is an upward movement, there must be a corresponding downward movement; whenever there is an odd number, there must be a connected even number; whenever there is an active element, there must be a corresponding passive element. In this way, the primary hexagram and its opposite hexagram interweave with each other, and adjacent hexagrams and similar hexagrams connect with each other. This arrangement is not restricted by the order of the eight palaces, nor is it bound by the sequence of the primary hexagram. Yet the resulting order coincides perfectly with the sequence of the eight palaces without disrupting their numerical arrangement, and it also harmonizes perfectly with the primary hexagram without contradicting its position. This is because this order is naturally established in the Later Heaven. The heavens and the earth, human beings, the seasons, days, and months all flow and circulate continuously, with movement and stillness each following their own rules, all conforming to this order.

故以卦象言，文王六十四卦，自乾坤起，以乾坤對舉，陰陽交行也；終於既未濟，以坎離互交，水火易位也。其中各卦，莫非此例，皆以比偶相及，對應相生，分之自成一卦，合之則為全序。

Therefore, in terms of the hexagram images, King Wen's sixty-four hexagrams begin with the hexagrams of Qian and Kun, pairing them together to signify the mutual interaction of yin and yang. They conclude with the hexagrams of Ji Ji and Wei Ji, allowing Kan and Li to intermingle, symbolizing the mutual exchange of water and fire. In between, each hexagram follows this pattern: they are all related to one another in pairs through adjacent pairings, and they correspond to each other in pairs to generate each other. Individually, each hexagram forms a complete hexagram on its own; collectively, they constitute the complete sequence of the entire text.

以卦雖六十四，而乾、坤、坎、離、頤、中孚、大小過八卦，獨不同象；其它五十六卦，皆反覆自為兩卦；則五十六卦，實二十八也。合之乾、坤、坎、離、頤、中孚、大小過八卦，共三十六卦，以應周天之數，而象萬物之類。

There are sixty-four trigrams in total, but eight of them, namely Qian, Kun, Kan, Li, Yi, Zhongfú, Da Guo, and Xiao Guo, are unique in that when they are viewed upside down, they remain the same. The remaining fifty-six trigrams each become another trigram when reversed, forming pairs of opposites. Thus, these fifty-six trigrams actually represent only twenty-eight distinct forms. Adding the eight special trigrams, there are a total of thirty-six trigrams, used to correspond to the degrees of the celestial circle and to symbolize the various categories of things in the world.

故其次序，以上下篇分括六十四卦，而皆統之於乾坤坎離；明天地為萬物之本，水火為二氣之宗，而合乎伏羲八卦方位四正之象也。故全易之序，皆以此四卦為主，反覆交互，上下錯綜，更以震、巽、艮、兌為用，縱橫應接，奇偶對生，以盡二氣之生化，而推五行之承制，蓋其旨意固如是也。

Therefore, this order uses the upper and lower parts to encompass the sixty-four hexagrams, and both parts are subordinate to the four hexagrams of Qian, Kun, Kan, and Li. This is to indicate that heaven and earth are the fundamental elements of all things, and water and fire are the masters of yin and yang energies. It also corresponds with the four cardinal directions of the eight trigrams in Fuxi's arrangement. Thus, the entire sequence of the Book of Changes revolves around these four hexagrams, allowing them to interact repeatedly and intermingle in a complex manner. The other four trigrams, Zhen, Xun, Gen, and Dui, serve as supplementary elements, interweaving and connecting with each other in all directions. Odd and even numbers are paired to exhaust the generation and transformation of yin and yang energies, and to demonstrate the relationships of succession and control among the five phases. This was the original intention.

至文王卦序之例，可得言者，則其卦之對舉，合之本宮卦序，必一與五世，二與四世，三與三世；游魂與游魂，歸魂與歸魂，皆不亂也。如屯蒙二卦對舉，屯為坎宮二世卦，蒙為離宮四世卦；又如同人大有二卦對舉，同人為離宮歸魂，大有為乾宮歸魂，是其所舉異宮，而仍同世也。

As for the arrangement of the hexagrams in the sequence of King Wen, there is another point worth noting: whenever two hexagrams are paired together, if we check them against the sequence of their respective trigrams, they must always be paired as first-generation hexagram with fifth-generation hexagram, second-generation with fourth-generation, and third-generation with third-generation. Similarly, wandering soul hexagrams are paired with wandering soul hexagrams, and returning soul hexagrams are paired with returning soul hexagrams, without any confusion. For example, the hexagrams Zun and Meng are paired together. Zun is the second-generation hexagram of the Kan trigram, while Meng is the fourth-generation hexagram of the Li trigram. Another example is the pairing of Tongren and Dayou. Tongren is the returning soul hexagram of the Li trigram, while Dayou is the returning soul hexagram of the Qian trigram. This shows that although the two paired hexagrams come from different trigrams, their generational positions remain consistent.

其次則乾、坤、坎、離常以對舉，以屬先天對宮也；震、巽、艮、兌或對舉，或比類，以屬於先天四隅卦也。又乾與坎，坤與離，或離與乾，坎與坤，亦比類連舉，以先天之乾坤，後天之坎離同位；先天乾以離為用，坤以坎為用，其位次相比並，有如比肩。

Next, the four trigrams Qian, Kun, Kan, and Li are often paired together, because in the Earlier Heaven arrangement they naturally belong to opposite trigrams facing each other. The four trigrams Zhen, Xun, Gen, and Dui are sometimes paired together or grouped by similarity, because in the Earlier Heaven arrangement they belong to the four corner trigrams. Additionally, Qian with Kan, Kun with Li, or Li with Qian, Kan with Kun, are also sometimes mentioned together as similar trigrams. This is because in the Earlier Heaven arrangement, the trigrams Qian and Kun correspond to the Later Heaven trigrams Kan and Li, which occupy the same position. In the Earlier Heaven arrangement, Qian uses Li, and Kun uses Kan, and these two trigrams are closely adjacent, standing side by side.

故其在後天有相對之象，有相類之象，亦猶乾與坤，坎與離也。震、巽、艮、兌亦然：震之於艮、於兌，巽之於兌、於艮，艮之於震、於巽，兌之於巽、於震，皆以比類連舉，如震與巽、艮與兌之對舉也。

Therefore, these four trigrams, when considered in the Later Heaven, have both opposing relationships and similar relationships, just like the relationship between Qian and Kun, or between Kan and Li. The trigrams Zhen, Xun, Gen, and Dui also follow this pattern: Zhen opposes Gen and Zhen opposes Dui; Xun opposes Dui and Xun opposes Gen; Gen opposes Zhen and Gen opposes Xun; Dui opposes Xun and Dui opposes Zhen. All of these can be paired as similar trigrams, just as Zhen and Xun, and Gen and Dui, are paired as opposing trigrams.

且在先天震巽為對，後天則震與兌對；先天艮兌為對，後天則艮與坤對；巽與乾對，其為比類者，在後天變對舉。故其序怛連舉也。又震與艮、巽與兌二卦獨舉，不以先後天對宮，為明四隅之卦，以交錯為先，以類及為重，不似乾、坤、坎、離四正之卦也。故其下篇序，震艮連及，巽兌並列，以先天方位次序，固如是對，而卦之性相同也。

In the Earlier Heaven arrangement, Zhen faces Xun, but in the Later Heaven arrangement, Zhen faces Dui; in the Earlier Heaven arrangement, Gen faces Dui, but in the Later Heaven arrangement, Gen faces Kun; Xun faces Qian. Previously, these were two trigrams adjacent to each other, but in the Later Heaven arrangement, they become pairs facing each other, so they are always mentioned together in the sequence of trigrams. Additionally, the pairs Zhen and Gen, Xun and Dui are mentioned separately and not paired according to the Earlier Heaven or Later Heaven opposite positions, to indicate that the trigrams in the four corners are primarily arranged in a crosswise manner and emphasize mutual relations, unlike the four cardinal trigrams Qian, Kun, Kan, and Li, which strictly adhere to opposite positions. Therefore, in the sequence of the next section, Zhen and Gen are mentioned consecutively, and Xun and Dui are arranged together: according to the Earlier Heaven positional order, they were originally facing each other, and moreover, the nature of the trigrams is similar to each other.

震艮一長男也，一少男；巽兌一長女，一少女；性類不殊，氣數可通。故其致用也順，為生也孚。風澤為中孚，澤風為太過；雷山為小過，山雷為頤；之四卦者，反覆不變，恰與乾、坤、坎、離同，其並舉有由來矣。

Zhen and Gen represent the eldest son and the youngest son respectively; Xun and Dui represent the eldest daughter and the youngest daughter respectively. Their nature and category are essentially the same, and their qi and numbers can communicate with each other. Therefore, when they function, they proceed smoothly without obstruction, and when they generate and nurture all things, they harmonize with each other. When Xun is above and Dui is below, it forms the hexagram Zhongfou; when Dui is above and Xun is below, it forms the hexagram Daguò. When Zhen is above and Gen is below, it forms the hexagram Xiaoguo; when Gen is above and Zhen is below, it forms the hexagram Yi. These four hexagrams remain the same when viewed upside down, just like Qian, Kun, Kan, and Li. This shows that they are intentionally paired together in the sequence of hexagrams.

又六十四卦，一往一復，無不相應，合之先天八卦方位，自可見也。如乾坤之後，繼以屯蒙，屯為水雷，蒙為山水。後天之用，始於震，終於艮，而藏機於坎。坎水以代坤，坤之氣見於坎，故坎陽體陰用。屯自水中陽出，蒙則山下水流；屯為往，蒙為復，一往一復，見氣之所化。

Furthermore, the sixty-four hexagrams alternate between movement and stillness, and none fail to correspond with each other; by comparing them with the positions of the Earlier Heaven Trigrams, this becomes evident. For example, after the Trigrams of Heaven and Earth come the hexagrams of Zhun and Meng. Zhun is composed of Kan above and Zhen below, representing the image of water and thunder; Meng is composed of Gen above and Kan below, representing the image of mountain and water. The function of the Later Heaven begins with Zhen and ends with Gen, with the key hidden in Kan. The water of Kan replaces the function of Kun, and the energy of Kun manifests within Kan, so Kan takes Yang as its essence and Yin as its function. Zhun represents the emergence of Yang energy from water, while Meng represents water flowing out from beneath the mountain; Zhun signifies movement, and Meng signifies return. Between movement and return, the manifestations of the vital energy become apparent.

陽動而陰靜，陰出而陽歸，故二卦對舉，而見一陰一陽之道。此後天生化之始，二氣往復之初，以交互而生，以循環而化。為卦止二，為象已多，天地之機以明，乾坤之用以啟，故繼乾坤而為六十四卦之首也。

Yang is active and Yin is static. When Yin energy moves, Yang energy returns. Therefore, the two hexagrams Zun and Meng are presented together, illustrating the alternating principle of Yin and Yang. This marks the beginning of later heaven generation and transformation, the first step of the reciprocal movement of Yin and Yang energies. They produce through mutual interaction and transform through continuous cycles. Although there are only two hexagrams, the symbolic meaning is already very rich: the mechanism of heaven and earth's operation is thus revealed, and the functions of Heaven and Earth are thus initiated. Therefore, they follow Heaven and Earth and are placed first among the sixty-four hexagrams.

雷之為物，動而為陽，靜而為陰，故出於地，而升於天。在後天，東方木也；木氣生於天，成於地；木數生於三，成於八。其本則天地也，其先則水火也；在先天水為始，而後天木為初。故傳曰帝出乎震，言萬物之始生也。然自出者，必有本；震之所本，坎也。

Thunder is a thing that, when active, belongs to Yang, and when still, belongs to Yin. Therefore, it arises from beneath the earth and ascends to the heavens. In the Later Heaven arrangement, Zhen (Thunder) is associated with the East, the direction of Wood. The vital energy of Wood originates in Heaven and takes form in the earth. The generative number of Wood is three, and its completed number is eight. Its root lies in Heaven and Earth, and its leading force is water and fire. In the Earlier Heaven arrangement, water is considered the beginning of all things, but in the Later Heaven arrangement, Wood is regarded as the starting point. Therefore, the "Commentary on the Hexagrams" says, "The Emperor arises from Zhen," referring precisely to the beginning of all things. However, wherever there is an origin, there must be a source; the fundamental basis upon which Zhen relies is Kan (Water).

坎為水，先天之始生，後天之根源；震自坎出，為先天化為後天之啟端，故屯卦為全易各卦之初始，象萬物之初生也。祇在卦爻求之，即可見矣。然生者必化，往者必復，此後天公例。既有屯，以象往生；自有蒙，以象復化。化於此者，即生於彼；往於昨者，必復於今。

The trigram Kan represents water, which is the beginning of all things in the Earlier Heaven and the origin of all things in the Later Heaven. The trigram Zhen arises from Kan, marking the starting point of the transformation from the Earlier Heaven to the Later Heaven. Therefore, the hexagram Zun is placed as the first hexagram in the entire Book of Changes, symbolizing the initial emergence of all things. By examining the lines of the hexagram, this can be clearly understood. However, whenever there is generation, there must also be transformation; whenever there is movement forward, there must also be return. This is the general principle of the Later Heaven. Since the hexagram Zun symbolizes forward movement and generation, there must naturally be the hexagram Meng symbolizing return and nurturing. What is transformed here will be generated elsewhere; what went out yesterday will surely return today.

此循環之定理。既有屯蒙以明其初氣，自有需訟以象其次數。氣數周流，生化無盡，而後萬物之象見，萬類之數明，其例固昭昭矣。就屯蒙卦言，在先天八卦，坤之左右，雷自水出，泉流山下。二者一自左上，一自右降，一升一降，仍還於原。坤用重坎，故用水不言地，明卦序之為後天也。

This is the principle of continuous cycles. Since the hexagrams Zhun and Meng explain the initial qi, there naturally exist the hexagrams Xu and Song to symbolize the subsequent qi numbers. Qi and numbers flow endlessly, generating and transforming without end, and thus the forms of all things become evident, and the numbers of all categories become clear. This system is inherently clear. Regarding the hexagrams Zhun and Meng, in the Earlier Heaven arrangement of the eight trigrams, they are positioned on either side of the Kun trigram: thunder arises from water, and spring water flows down the mountain. One rises from the left, the other descends from the right, ascending and descending, eventually returning to their original positions. Here, the Kun trigram uses the overlapping Kan trigram to function, so it only speaks of water and not of earth. This clearly indicates that this sequence of hexagrams belongs to the Later Heaven arrangement.

然後天者，仍出於先天，仍歸於先天，故需訟二卦，則一為水天，一為天水。坎本得乾陽為體，故游魂之卦，仍溯源於所生，而需訟之象，乃往復於乾坎也。需訟二卦，一為坤宮之游魂，一為離宮之游魂；坤之游魂，即乾宮之氣所化；離之游魂，即坎宮之氣所化，則需卦為乾坤二氣之交互，訟卦即離坎二氣之循環。

However, Later Heaven ultimately originates from Earlier Heaven and eventually returns to Earlier Heaven. Therefore, the hexagrams "Need" and "Song" represent the image of water above heaven below (upper Kan, lower Qian) and heaven above water below (upper Qian, lower Kan), respectively. The hexagram Kan originally takes the yang line of Qian in the central position as its body, so it belongs to the category of wandering souls. Hence, the images of "Need" and "Song" alternate between Qian and Kan. These two hexagrams are wandering souls of the K'un palace and the Li palace respectively. The wandering soul of the K'un palace is actually transformed from the qi of the Qian palace, and the wandering soul of the Li palace is transformed from the qi of the Kan palace. Thus, the hexagram "Need" represents the mutual interaction of the qi of Qian and K'un, while the hexagram "Song" represents the cyclic transformation of the qi of Li and Kan.

以水天合而為需，水上於天，即坎與乾交，而陽上升；以天水合而為訟，天下近水，即乾與坎交，而陽下降。一升一降，一往一復，自相偶也，故需與訟二卦對舉，恰相當其位，而氣數亦相得。

Water above and Heaven below form the hexagram Need, where water floats above Heaven, meaning the trigrams Kan (Water) and Qian (Heaven) meet, and the yang energy rises; Heaven above and Water below form the hexagram Suing, where Heaven descends close to Water, meaning the trigrams Qian and Kan meet, and the yang energy descends. One rising and one falling, one moving forward and one returning, naturally form a pair. Therefore, the hexagrams Need and Suing are presented together, their positions exactly corresponding, and their energies and numbers complement each other.

自先天八卦言之，乾與坎為比類，即後天之對位也。在後天坎代坤用，有似於泰否二卦，與晉明夷卦二卦相類。晉與明夷，一為火地，一為地火，為坤與離升降交互之卦。離在後天代乾，與泰否亦相似，又與既未濟亦相近也。蓋先天為泰否，後天為既未濟。

From the perspective of the Earlier Heaven Trigrams, Qian and Kan belong to adjacent trigrams of the same type. However, in the Later Heaven arrangement, they become opposite positions. In the Later Heaven, Kan takes the role of Kun, and this relationship is somewhat similar to the two trigrams Tai and Po. It is also comparable to the two trigrams Jin and Mingyi. Jin is the trigram of fire on earth, while Mingyi is the trigram of earth on fire; both are formed by the interaction of Kun and Li rising and falling. In the Later Heaven, Li takes the role of Qian, so these two trigrams are similar to Tai and Po, and also close to Ji Ji and Wei Ji. In summary, the trigrams Tai and Po are used to explain the Earlier Heaven, while Ji Ji and Wei Ji are used to explain the Later Heaven.

半先半後，則需訟與晉明夷也，皆乾坤坎離交錯往復之卦，即陰陽二氣交互升降之象也。故皆對舉以成序，仍本於八卦位次者也。需訟在八宮，以坤與離對；在八卦位次，以乾與坎合。對合之間，見其交錯之出於自然，明其生化之有其定序，不少差也。不獨其世同也，

As for the four hexagrams that are half belonging to the Earlier Heaven and half to the Later Heaven, they are the hexagrams of Need, Strife, Progress, and Bright Abundance. They are all composed of the trigrams of Heaven, Earth, Water, and Fire alternating and interchanging, which represent the image of the mutual rise and fall of the two energies of yin and yang. Therefore, they are paired in pairs to form sequences, still following the order of the eight trigrams. In terms of the eight palaces, Need and Strife are opposite between the Earth Palace and the Fire Palace; in terms of the order of the eight trigrams, they are paired between Heaven and Water. Between this pairing and combination, one can see that the interweaving is natural, and one can understand that the process of generation and transformation has a definite order, without any error. Moreover, the two paired hexagrams not only share the same worldly position,

凡此卦序，其例皆然，皆自氣數所至，生化所成，非故為之序也。故六十四卦之序，循環終始，一一相得；而八卦之用，往來升降，一一相當；初無不偶之處，亦無相逆之情。其相對舉也，正一陰一陽之道，後天生化之理然也。合之洛書，征之太極，自易明曉；至其續之義，見序卦傳者，不贅述也。

All the sequences of the sixty-four hexagrams follow this pattern: they are the results of the movement of qi and the natural process of generation and transformation, not deliberately arranged by anyone. Therefore, the sequence of the sixty-four hexagrams continues cyclically from beginning to end, with each hexagram complementing the others. The functions of the eight trigrams are interrelated in their movement and changes, being appropriate in every aspect; there is no place where any is isolated or mismatched, nor any instance of contradiction between them. The reason they are paired and presented in pairs is precisely in accordance with the saying "yin and yang together are called the Dao," which reflects the inherent principle of generation and transformation in the Later Heaven. Comparing them with the Luo Writing and verifying them with the concept of the Supreme Ultimate naturally makes this clear. As for the meaning of the sequence of hexagrams following one another, the "Sequence of Hexagrams" passage has already explained it, so there is no need to repeat it here.