天地之气，始于子中。子居正北，其名朔方，又曰幽都。幽者，隐也，微也，谓万物未
生，幽隐未可察也。朔者，尽也，初也，谓阴气之极，阳气之始也。邵子曰∶阳气自北方而
生，至北方而尽。故尧典谓北方为朔易，朔易者，除旧更新之谓也。盖其自子至亥，周而复
始，以成东西南北、春夏秋冬之位。子午为阴阳之极，卯酉为阴阳之中，是为四正；四正定
而每隅间之以二，是为十二宫；每隅间之以五，是为二十四向。再按洛书九宫，位分八卦。
伏羲八卦曰先天，其次则干南坤北，离东坎西，以左右分数之，自南而东者，曰干一兑二，离
三震四，自西而北者，曰巽五坎六，艮七坤八也；文王八卦曰后天，离象火而居南，坎象水而
居北，震象木而居东，兑象金而居西，以次而数，则干起西北，顺而左旋，曰干坎艮震巽离坤
兑，以周八宫也。先天以乾坤分天地而定上下之位，后天以坎离分水火而定南北之方。先
天以干居正南，坤居正北，其阳在南，其阴在北；后天以干居西北，坤居西南，其阳在北，其
阴在南。故先天以巽离兑虽为阴卦而本乎干体，故位于上，震坎艮虽为阳卦而本乎坤体，
故位于下；后天以干来交坤，化为坎水而居北，坤去交干，变为离火而居南，天体倚北而偏
于西，故干之退位于西北，地体属土而继乎火，故坤之寄位于西南，巽居东南，木先火地，艮
止东北，因对坤方，干父在北，故坎艮震三子随之而居下，坤母在南，故巽离兑三女随之而
向前。先天以上下分左右，故以乾坤为纵，六子为横；后天以东西界阴阳，故以震兑为横，六
卦为纵。先天以乾坤之末交二至，离为日，故升于东，坎为月，故生于西；后天以震兑之中
当二分，自震而南，巽离为木火之地，自兑而北，干坎为金水之乡，故易传曰帝出乎震，齐乎
巽，相见乎离，致役乎坤，说言乎兑，战乎干，劳乎坎，成言乎艮，正以明东南春夏之盛，西北
秋冬之衰。是先天者，所以言六合之象；后天者，所以明气候之详。故邵子曰∶先天为易之
体，后天为易之用也。夫天体正圆，面南背北。南北两极，乃其运转之枢。北极居上而为
尊，南极居下而为对。邵子曰∶天之阳在南，阴在北；地之阴在南，阳在北。天阳在南，故日
处之；地刚在北，故山处之。河图括地象曰∶西北为天门，东南为地户。内经曰∶天不足西
北，地不满东南。故曰天门无上，地户无下。又曰东南方阳也，阳者其精降于下；西北方阴
也，阴者其精奉于上。故阳降于下，则阳盛阴微而东南之方常多热；阴奉于上，则阴盛阳微
而西北之地常多寒。昆仑峙于西北，故西北高而多山；沧海浴于东南，故东南下而多水。
高者多寒，下者多热。东南阳胜，则气为熏蒸，而春夏之气多烟雾；西北阴胜，则气为凛冽，
而秋冬之气多风霾。中国形胜，居昆仑之东南，故天下之山脉皆起于昆仑，山脉之所起，即
水源之所发。是以中国之山，自西北而来；中国之水，亦自西北而发。朱子曰∶大凡两水夹
行，中间必有山；两山夹行，中间必有水。试考中国舆图，其山脉发自昆仑，委蛇二万四千
三百余里而入中国，分大龙为三障于外，大河为两川于中，以成中国河山之胜 。由是四
方立而有十二辰之会，二十八宿辨而有分野之详。三代分为九州，虞舜分为十二州，周末
分为十二国，秦为三十六郡，汉为十三部，晋为十九州，宋为二十二州，唐为十道，宋为二十
三路，元为十二省二十二道，至我朝则分为两直隶十三省，而天象舆图古今一致矣。
天地之气，起始于子时正中。子位处于正北方，其名为朔方，又称幽都。“幽”意为隐蔽、微细，指万物尚未生成，处于隐蔽不可见的状态。“朔”意为终结、初始，指阴气达到极点，阳气开始萌生。邵雍说：阳气从北方产生，至北方而穷尽。所以《尚书·尧典》称北方为“朔易”，所谓“朔易”，就是除旧更新的意思。大概从子到亥，循环往复，从而形成东、西、南、北以及春、夏、秋、冬的位置关系。子午是阴阳的极点，卯酉是阴阳的中点，这称为四正；确定了四正之后，每个方位之间再间隔两个地支，这就构成了十二宫（十二地支）；每个方位之间再间隔五个地支，这就构成了二十四向（二十四山）。再按照洛书九宫的布局，方位分为八卦。伏羲八卦称为先天八卦，其次是乾在南、坤在北、离在东、坎在西，按左右分数排列，从南向东依次是：乾一、兑二、离三、震四；从西向北依次是：巽五、坎六、艮七、坤八。文王八卦称为后天八卦，离象征火而居南方，坎象征水而居北方，震象征木而居东方，兑象征金而居西方，按顺序数来，则乾起于西北，顺行左旋，依次为乾、坎、艮、震、巽、离、坤、兑，以此周遍八方。先天八卦以乾坤分别天地来确定上下之位，后天八卦以坎离分别水火来确定南北之方。先天八卦中，乾居正南，坤居正北，阳在南，阴在北；后天八卦中，乾居西北，坤居西南，阳在北，阴在南。所以先天八卦中，巽、离、兑虽然是阴卦，但本源于乾体，所以位于上方；震、坎、艮虽然是阳卦，但本源于坤体，所以位于下方。后天八卦中，乾交于坤，化为坎水而居北方；坤交于乾，变为离火而居南方。天体倚靠北方而偏于西方，所以乾退位于西北；地体属土而继乎火，所以坤寄位于西南。巽居东南，因为木先于火地；艮止于东北，因为对着坤方。乾父在北方，所以坎、艮、震三个儿子随之居于下方；坤母在南方，所以巽、离、兑三个女儿随之居于前方。先天八卦以上下分左右，所以以乾坤为纵轴，六子卦为横轴；后天八卦以东西界分阴阳，所以以震、兑为横轴，六卦为纵轴。先天八卦中，乾坤的末爻相交于二至（冬至、夏至），离为日，所以升起于东；坎为月，所以生于西。后天八卦中，震、兑之中当二分（春分、秋分），自震向南，巽、离是木火之地；自兑向北，乾、坎是金水之乡。所以《易经·说卦传》说：“帝出乎震，齐乎巽，相见乎离，致役乎坤，说言乎兑，战乎干，劳乎坎，成言乎艮。”这正是为了说明东南春夏的旺盛，以及西北秋冬的衰败。这是先天八卦用来阐述六合的形象，后天八卦用来阐明气候的详细情况。所以邵雍说：先天是《易》的本体，后天是《易》的作用。
天的形体正圆，面南背北。南北两极，是天体运转的枢纽。北极居上而尊贵，南极居下而对峙。邵雍说：天之阳在南，阴在北；地之阴在南，阳在北。天阳在南，所以太阳处在那里；地刚在北，所以高山处在那里。《河图括地象》说：西北为天门，东南为地户。《黄帝内经》说：天不足于西北，地不满于东南。所以说天门无上，地户无下。又说：东南方属阳，阳的精气下降于下；西北方属阴，阴的精气奉养于上。所以阳气下降于下，则阳盛阴微，东南方向常多热；阴气奉养于上，则阴盛阳微，西北地方常多寒。昆仑山耸立于西北，所以西北高且多山；沧海沐浴于东南，所以东南低且多水。高的地方多寒，低的地方多热。东南阳气胜，则空气为熏蒸之气，所以春夏之气多烟雾；西北阴气胜，则空气为凛冽之气，所以秋冬之气多风霾。中国的地理形势，位于昆仑山的东南，所以天下的山脉都发源于昆仑山，山脉的发源地，也就是水源的发源地。因此中国的山，从西北而来；中国的水，也从西北发出。朱熹说：大凡两条水流夹行，中间必定有山；两座山夹行，中间必定有水。试考察中国的地图，其山脉发源于昆仑，蜿蜒两万余里进入中国，分出大龙作为外部的三道屏障，大河作为中间的两大川流，从而成就了中国山河的胜景。由此确立四方而有十二辰的会合，分辨二十八宿而有分野的详细记载。夏商周三代分为九州，虞舜分为十二州，周末分为十二国，秦朝为三十六郡，汉朝为十三部，晋朝为十九州，宋朝为二十二州，唐朝为十道，宋朝为二十三路，元朝为十二省二十二道，到了我朝则分为两直隶十三省，而天象与地图古今一致。
The Qi of Heaven and Earth begins at the middle of Zi (Rat hour). Zi is located in the due North, named Shuofang (Northern Direction), also called Youdu (Dark Capital). "You" means hidden and subtle, referring to the state where all things have not yet been born, hidden and unobservable. "Shuo" means end and beginning, referring to the extreme of Yin Qi and the start of Yang Qi. Shao Yong said: Yang Qi arises from the North and reaches its limit in the North. Therefore, the *Book of Documents* states that the North is called "Shuoyi" (Change of Beginning), which means getting rid of the old and renewing the new. Generally, from Zi to Hai, it cycles back to the start, thereby establishing the positions of East, West, South, North, and Spring, Summer, Autumn, Winter. Zi and Wu are the extremes of Yin and Yang; Mao and You are the middles of Yin and Yang; these are called the Four Cardinal Directions. Once the Four Cardinals are fixed, two branches are interspersed between each corner, forming the Twelve Palaces (Twelve Earthly Branches); five branches are interspersed between each corner, forming the Twenty-Four Orientations (Twenty-Four Mountains). Furthermore, according to the Nine Palaces of the Luoshu, positions are divided into the Eight Trigrams. The Fuxi Bagua is called the Pre-Heaven Bagua. In this arrangement, Qian is in the South, Kun in the North, Li in the East, and Kan in the West. Counting by left and right, from South to East: Qian 1, Dui 2, Li 3, Zhen 4; from West to North: Xun 5, Kan 6, Gen 7, Kun 8. The King Wen Bagua is called the Post-Heaven Bagua. Li symbolizes Fire and resides in the South; Kan symbolizes Water and resides in the North; Zhen symbolizes Wood and resides in the East; Dui symbolizes Metal and resides in the West. Counting in order, Qian starts in the Northwest and rotates counter-clockwise: Qian, Kan, Gen, Zhen, Xun, Li, Kun, Dui, thus circling the Eight Palaces. The Pre-Heaven Bagua uses Qian and Kun to divide Heaven and Earth, establishing the positions of Upper and Lower. The Post-Heaven Bagua uses Kan and Li to divide Water and Fire, establishing the directions of North and South. In the Pre-Heaven Bagua, Qian is in the due South, Kun in the due North; Yang is in the South, Yin in the North. In the Post-Heaven Bagua, Qian is in the Northwest, Kun in the Southwest; Yang is in the North, Yin in the South. Thus, in the Pre-Heaven Bagua, although Xun, Li, and Dui are Yin trigrams, they originate from the body of Qian, so they are positioned above; although Zhen, Kan, and Gen are Yang trigrams, they originate from the body of Kun, so they are positioned below. In the Post-Heaven Bagua, Qian interacts with Kun, transforming into Kan Water residing in the North; Kun interacts with Qian, transforming into Li Fire residing in the South. The body of Heaven leans towards the North but deviates to the West, so Qian retreats to the Northwest. The body of Earth belongs to Earth element and follows Fire, so Kun resides provisionally in the Southwest. Xun resides in the Southeast, as Wood precedes Fire/Earth. Gen stops in the Northeast, facing Kun. Since the Father Qian is in the North, the three sons Kan, Gen, and Zhen follow him to reside below. Since the Mother Kun is in the South, the three daughters Xun, Li, and Dui follow her to reside forward. The Pre-Heaven Bagua divides Left and Right by Upper and Lower, so Qian and Kun form the vertical axis, and the Six Children form the horizontal axis. The Post-Heaven Bagua divides Yin and Yang by East and West, so Zhen and Dui form the horizontal axis, and the six trigrams form the vertical axis. In the Pre-Heaven Bagua, the last lines of Qian and Kun intersect at the Solstices (Dongzhi and Xiazhi). Li is the Sun, so it rises in the East; Kan is the Moon, so it is born in the West. In the Post-Heaven Bagua, the middles of Zhen and Dui correspond to the Equinoxes (Chunfen and Qiufen). From Zhen southward, Xun and Li are lands of Wood and Fire; from Dui northward, Qian and Kan are regions of Metal and Water. Therefore, the *Commentary on the Appended Phrases* says: "The Emperor emerges from Zhen, is arranged by Xun, meets in Li, renders service in Kun, speaks in Dui, fights in Qian, labors in Kan, and completes words in Gen." This clearly illustrates the prosperity of Spring and Summer in the Southeast and the decline of Autumn and Winter in the Northwest. The Pre-Heaven Bagua describes the image of the Six Directions; the Post-Heaven Bagua clarifies the details of climate. Thus, Shao Yong said: The Pre-Heaven is the substance of Yi (Changes); the Post-Heaven is the function of Yi.
The body of Heaven is perfectly round, facing South and backing North. The North and South Poles are the pivots of its rotation. The North Pole is above and honored; the South Pole is below and opposite. Shao Yong said: The Yang of Heaven is in the South, Yin in the North; the Yin of Earth is in the South, Yang in the North. Since Heaven's Yang is in the South, the Sun resides there. Since Earth's rigidity is in the North, Mountains reside there. The *Hetu Kuodi Xiang* states: The Northwest is the Heavenly Gate, the Southeast is the Earthly Door. The *Huangdi Neijing* states: Heaven is deficient in the Northwest, Earth is incomplete in the Southeast. Thus, it is said that the Heavenly Gate has no upper limit, and the Earthly Door has no lower limit. It is also said: The Southeast direction is Yang; the essence of Yang descends downwards. The Northwest direction is Yin; the essence of Yin is offered upwards. Therefore, when Yang descends downwards, Yang becomes abundant and Yin weak, so the Southeast direction is often hot. When Yin is offered upwards, Yin becomes abundant and Yang weak, so the Northwest region is often cold. Kunlun Mountain stands in the Northwest, so the Northwest is high and mountainous. The Great Ocean bathes in the Southeast, so the Southeast is low and watery. High places are often cold; low places are often hot. In the Southeast, Yang prevails, causing air to be steaming, so the Qi of Spring and Summer is often misty/smoky. In the Northwest, Yin prevails, causing air to be biting/cold, so the Qi of Autumn and Winter is often windy/hazy. China's geographical advantage lies southeast of Kunlun, so all mountain ranges in the world originate from Kunlun. Where mountains originate, water sources also begin. Therefore, China's mountains come from the Northwest; China's waters also originate from the Northwest. Zhu Xi said: Generally, where two rivers flow side by side, there must be a mountain in between; where two mountains run parallel, there must be water in between. Examining the map of China, its mountain range originates from Kunlun, winding over twenty-four thousand three hundred li into China. It divides the great dragon into three barriers outside, and the great river into two channels inside, thereby achieving the grandeur of China's rivers and mountains. From this, the four directions are established, meeting the Twelve Earthly Branches; the Twenty-Eight Mansions are distinguished, detailing the territorial divisions. The Three Dynasties divided the land into Nine Provinces; Yu Shun divided it into Twelve Provinces; the late Zhou period divided it into Twelve States; Qin had Thirty-Six Commanderies; Han had Thirteen Departments; Jin had Nineteen Provinces; Song had Twenty-Two Provinces; Tang had Ten Circuits; Song had Twenty-Three Routes; Yuan had Twelve Provinces and Twenty-Two Circuits. In our dynasty, it is divided into Two Directly Administered Regions and Thirteen Provinces. The celestial phenomena and maps remain consistent from ancient times to the present.