The twenty-eight mansions successively appear in the southern sky at the position of the hour of Wu, which is the central star.

正月上旬日在女，初昏胃見南方午位；中旬日在虛，初昏昴見南方午位；下旬日在危，初昏畢見南方午位。二月上半月日在室，初昏觜見南方午位；下半月日在壁，初昏參見南方午位。三月上半月日在奎，初昏井見南方午位；下半月日在婁，初昏鬼見南方午位。

In the first ten days of the first lunar month, the sun is in the Girl mansion, and at the beginning of dusk, the Stomach mansion appears in the south at the position of the午 (Wu) hour; in the middle ten days, the sun is in the Emptiness mansion, and at the beginning of dusk, the Hairy Head mansion appears at the south Wu position; in the last ten days, the sun is in the Rooftop mansion, and at the beginning of dusk, the Net mansion appears at the south Wu position. In the second lunar month, during the first half of the month, the sun is in the Encampment mansion, and at the beginning of dusk, the Turtle Beak mansion appears at the south Wu position; during the second half of the month, the sun is in the Wall mansion, and at the beginning of dusk, the Three Stars mansion appears at the south Wu position. In the third lunar month, during the first half of the month, the sun is in the Legs mansion, and at the beginning of dusk, the Well mansion appears at the south Wu position; during the second half of the month, the sun is in the Bond mansion, and at the beginning of dusk, the Ghost mansion appears at the south Wu position. This is the method of using 'middle stars' to verify the season and the position of the twenty-eight mansions. At the beginning of night, observe which mansion is located in the south, and thus determine the actual position of the mansions corresponding to the seasons.

四月上旬日在胃，初昏柳見南方午位；中旬日在昴，初昏星見南方午位；下旬日在畢，初昏張見南方午位。五月上半月日在觜，初昏翼見南方午位；下半月日在參，初昏軫見南方午位。六月上半月日在井，初昏角見南方午位；下半月日在鬼，初昏亢見南方午位。

In the first ten days of April, the sun was in the Stomach mansion, and at the beginning of dusk, the Willow mansion appeared in the south direction at the position of Wu; in the middle ten days, the sun was in the Hairy Head mansion, and at the beginning of dusk, the Star mansion appeared at the Wu position; in the last ten days, the sun was in the Net mansion, and at the beginning of dusk, the Extended Net mansion appeared at the Wu position. In May, during the first half of the month, the sun was in the Turtle Beak mansion, and at the beginning of dusk, the Wings mansion appeared at the Wu position; during the second half of the month, the sun was in the Three Stars mansion, and at the beginning of dusk, the Chariot mansion appeared at the Wu position. In June, during the first half of the month, the sun was in the Well mansion, and at the beginning of dusk, the Horn mansion appeared at the Wu position; during the second half of the month, the sun was in the Ghost mansion, and at the beginning of dusk, the Neck mansion appeared at the Wu position. It is evident that the sun moves through about two mansions each month, and the mansion appearing at dusk also follows in sequence.

七月上旬日在柳，初昏氐見南方午位；中旬日在星，初昏房見南方午位；下旬日在張，初昏心見南方午位。八月上半月日在翼，初昏尾見南方午位；下半月日在軫，初昏箕見南方午位。九月上半月日在角，初昏斗見南方午位；下半月日在亢，初昏牛見南方午位。

In the first ten days of July, the sun was in the Willows mansion, and at the beginning of dusk, the Root mansion appeared in the south at the position of Wu; in the middle ten days, the sun was in the Star mansion, and at the beginning of dusk, the Room mansion appeared at the position of Wu; in the last ten days, the sun was in the Extended Net mansion, and at the beginning of dusk, the Heart mansion appeared at the position of Wu. In August, during the first half of the month, the sun was in the Wings mansion, and at the beginning of dusk, the Tail mansion appeared at the position of Wu; during the second half of the month, the sun was in the Chariot mansion, and at the beginning of dusk, the Winnowing Basket mansion appeared at the position of Wu. In September, during the first half of the month, the sun was in the Horn mansion, and at the beginning of dusk, the Dipper mansion appeared at the position of Wu; during the second half of the month, the sun was in the Neck mansion, and at the beginning of dusk, the Ox mansion appeared at the position of Wu. During autumn, the mansion that appears at dusk has moved from the eastern Azure Dragon to the northern Black Tortoise.

十月上旬日在氐，初昏女見南方午位；中旬日在房，初昏虛見南方午位；下旬日在心，初昏危見南方午位。十一月上半月日在尾，初昏室見南方午位；下半月日在箕，初昏壁見南方午位。十二月上半月日在斗，初昏奎見南方午位；下半月日在牛，初昏婁見南方午位。

In the first ten days of the tenth lunar month, the sun is in theRoot mansion, and at the beginning of dusk, theGirl mansion appears in the south direction at the午 position; in the middle ten days, the sun is in theRoom mansion, and at the beginning of dusk, theEmptiness mansion appears at the午 position; in the last ten days, the sun is in theHeart mansion, and at the beginning of dusk, theRooftop mansion appears at the午 position. In the eleventh lunar month, during the first half of the month, the sun is in theTail mansion, and at the beginning of dusk, theEncampment mansion appears at the午 position; during the second half of the month, the sun is in theWinnowing Basket mansion, and at the beginning of dusk, theWall mansion appears at the午 position. In the twelfth lunar month, during the first half of the month, the sun is in theDipper mansion, and at the beginning of dusk, theLegs mansion appears at the午 position; during the second half of the month, the sun is in theOx mansion, and at the beginning of dusk, theBond mansion appears at the午 position. The sun moves through the twelve months in a cycle, returning to the order of the first lunar month.

子自須女八度，至危十五度，凡三十度有奇，為齊之分野，屬青州，今山東登州、萊州、濟南、東昌之地是也。丑自南斗十二度至須女七度，凡三十度有奇，為吳越之分野，屬揚州，今南京、鳯陽等十四府，浙江杭州等十一府，江西南昌等十三府，廣東廣州等十府，廣西梧州之地是也。

The concept of "fenn yi" refers to dividing the celestial constellations into the twelve earthly branches and assigning them to different regions on earth, to correspond with the influence of stars and atmospheric phenomena. The position of Zi corresponds to the area from the eighth degree of Su Nu to the fifteenth degree of Wei Xu, covering more than thirty degrees, which is the fenn yi of the state of Qi, belonging to the state of Qingzhou, corresponding to the modern regions of Dengzhou, Laizhou, Jinan, and Dongchang in Shandong. The position of Chou corresponds to the area from the twelfth degree of Nan Dou to the seventh degree of Su Nu, covering more than thirty degrees, which is the fenn yi of Wu and Yue, belonging to the state of Yangzhou, corresponding to the modern regions of Nanjing and Fengyang in Jiangsu, Hangzhou in Zhejiang, Nanchang in Jiangxi, Guangzhou in Guangdong, and Wuzhou in Guangxi.

寅自尾十度至南斗十一度，凡三十度有奇，為燕之分野，屬幽州，今京師北直隸、河間、保定、永定、永平、隆慶、宣府、保安、遼東之地是也。卯自氐五度至尾九度，凡三十度有奇，為宋之分野，屬豫州，今南直隸、豐沛之地是也。

The position of寅 (Yin) starts from the fifth degree of theRoot mansion (Di Xu) and ends at the eleventh degree of the南斗 (Nan Dou), covering more than thirty degrees, which is the territory corresponding to Yan State, belonging to Youzhou, corresponding to today's Beijing's northern direct-controlled area, as well as Hejian, Baoding, Yongding, Yongping, Longqing, Xuanfu, Bao'an, and Liaodong regions. The position of卯 (Mao) starts from the fifth degree of the氐宿 (Di Xu) and ends at the ninth degree of the尾宿 (Wei Xu), also covering more than thirty degrees, which is the territory corresponding to Song State, belonging to Yuzhou, corresponding to today's southern direct-controlled area's Feng County and Pei County. The two positions cover areas to the north and central regions respectively, with the same number of star degrees, but the extent of the corresponding prefectures and states differs greatly.

辰自軫十二度至氐四度，凡三十度有奇，為鄭之分野，屬兗州，今河南開封、汝寧之地是也。巳自張十七度至軫十一度，凡三十度有奇，為楚之分野，屬荊州，今河南南陽、陜西漢中、湖廣武昌等十府，均州、四川夔州半入，廣西桂、柳、寧之地是也。

The position of Chen is from the 12th degree of Chen Zhen to the 4th degree of Di Shi, covering more than thirty degrees, which is the territory of Zheng state, belonging to Yanzhou, corresponding to the area around Kaifeng and Ruining in today's Henan province. The position of Si starts from the 17th degree of Zhang Xu to the 11th degree of Chen Zhen, covering more than thirty degrees, which is the territory of Chu state, belonging to Jingzhou, corresponding to the area of Nanyang in today's Henan province, Hanzhong in Shaanxi province, Wuchang in Huguang province, and ten prefectures including Junzhou and Kuizhou in Sichuan province, as well as Guilin, Liuzhou, and Nanning in Guangxi province. The territory covered by Si is the widest, so the star fields of Chu extend from the central plains all the way to the southern regions of Lingnan.

午自柳九度至張十六度，凡三十度有奇，為周之分野。屬營州，今河一府柳，貴州銅仁星，張屬河南之南陽。未自東井十六度至柳八度，凡三十度有奇，為秦之分野，屬雍州，今河南洛陽、陜西都司西平、鞏昌、延溪、寧夏，雲南鶴慶等軍民府之地是也。

The position of Wu is from the ninth degree of Liuxu to the sixteenth degree of Zhangsu, covering more than thirty degrees, which is the territory corresponding to the state of Zhou, belonging to Yingzhou; today, a certain prefecture corresponds to Liuxu, Guizhou's Tongren corresponds to Xingsu, and Zhangsu belongs to Nanyang in Henan (this sentence's original text is incomplete and is transcribed as is). The position of Wei starts from the sixteenth degree of Dongjing to the eighth degree of Liuxu, covering more than thirty degrees, which is the territory corresponding to the state of Qin, belonging to Yongzhou, which is today's Luoyang in Henan, Xiping, Gongchang, Yanyi, Ningxia in Shaanxi's military and civilian prefectures, as well as Yunnan's Heqing.

申自畢十二度至東井十五度，凡三十度有奇，為晉、魏之分野，屬梁州，一曰益州，今山西太原、大同、平陽、澤潞、四川順慶、於藩、疊溪、雲南十五府、貴州銅仁八府之地是也。酉自胃七度至畢十一度，凡三十度有奇，為趙之分野，屬冀州，今北直隸順德、廣平之地是也。

The position of Shen corresponds to the section starting from the seventh degree of Bi Xu and ending at the fifteenth degree of Dong Jing, covering more than thirty degrees. This area is the territory of Jin and Wei, belonging to Liangzhou, also known as Yizhou. It includes today's Taiyuan, Datong, Pingyang, Zelü in Shanxi, Shunqing, Yufan, Diexi in Sichuan, fifteen prefectures in Yunnan, and eight prefectures in Guizhou such as Tongren. The position of You starts from the seventh degree of Wei Xu and ends at the eleventh degree of Bi Xu, also covering more than thirty degrees. This area is the territory of Zhao, belonging to Jizhou, which corresponds to today's northern Zhili's Shunde and Guangping regions. These two positions are adjacent, and their corresponding phenomena mostly occur in the areas of He Dong and He Bei.

戌自奎五度至胄六度，凡三十度有奇，為魯之分野，屬徐州，今山東兗州之地是也。亥自危十六度至奎四度，凡三十度有奇，為衛之分野，屬幷州，今北直隸大名，河南彰德府、懷慶、衛輝之地是也。

The position of Xu is from the fifth degree of Kui mansion to the sixth degree of Wei mansion, covering more than thirty degrees, which is the territory corresponding to Lu state, belonging to Xu commandery, that is, the area around Yanzhou in present-day Shandong. The position of Hai starts from the sixteenth degree of Wei mansion to the fourth degree of Kui mansion, covering more than thirty degrees, which is the territory corresponding to Wei state, belonging to Bingzhou, that is, the area around Daming in present-day Beizhili, as well as Zhangde, Huaiqing, and Weihui in present-day Henan. The twelve branches complete the distribution of the twenty-eight mansions' degrees in a full cycle.

此天星下臨之妙用也。蓋星者，氣之清而上者也；地者，氣之濁而下者也。故天分星宿，地列山川，氣行於地，形麗乎天，《經》所謂“天有象，地有形，上下相須而成一體”者也。故羅經二十四位，各有天星主之，星吉則吉，星凶則凶。

This describes the subtle application of the celestial star mansions descending to the earth. Stars are the clear and ascending qi, while earth is the turbid and descending qi. Therefore, the heavens distribute star mansions, and the earth arranges mountains and rivers; qi moves through the earth, and forms manifest in the heavens, which is exactly what the Qingnang Jing says: "The heavens have star formations, the earth has physical forms, and heaven and earth depend on each other to form a single whole." Therefore, the twenty-four directions on the luojing each have a governing star: if the assigned star is auspicious, that direction is auspicious; if the assigned star is inauspicious, that direction is inauspicious.

幹配天廐星，又曰節越，曰北極，曰亢陽。坤配天鉞星，又曰陰玄，曰玄戈，曰老陰。坎配天壘星，又曰陽光，曰太陰。離配天廟星，又曰陽權，曰天馬，曰太陽，曰游魂。辰配天罡星，又曰亢金。戌配天魁星，又曰婁金，曰鼓盆。申配天闋星，又曰傳送。寅配天棓星，又曰功曹。

The twenty-four mountains each correspond to a specific star and its alternate names. When using this system, first determine which star is associated with the particular mountain, then judge the fortune based on the star's auspiciousness or inauspiciousness. The乾 position corresponds to the Tianjiu star, also known as Jieyue, Beijiu, and Kangle; the坤 position corresponds to the Tianyue star, also known as Yinxuan, Xianguo, and Lao Yin; the坎 position (Zi) corresponds to the Tianlei star, also known as Yangguang and Taiyin; the离 position (Wu) corresponds to the Tianmiao star, also known as Yangquan, Tianma, Taiyang, and Youhun; the辰 position corresponds to the Tian Gang star, also known as Kangjin; the戌 position corresponds to the Tiankui star, also known as Loujin and Gupen; the申 position corresponds to the Tianque star, also known as Chuyong; and the寅 position corresponds to the Tianbang star, also known as Gongcao. These eight positions are located in the four cardinal directions and the four beginning seasons.

甲配天苑星，又曰天統，曰陰機。乙配天官星，又曰官騎。壬配天輔星，又曰陰權。癸配天漢星，又曰陰光，曰搖光，曰北道。艮配天市垣陽樞星，亦曰天樞。巽配太乙星，亦曰陽旋。卯配陽衡星，亦曰天理，曰阿香，曰天命廉貞。酉配少微星，亦曰陽闓。亥配天皇星紫微垣，亦曰天門。

The Heavenly Stem Jia corresponds to the Tian Yuan star, also known as Tian Tong and Yin Ji; Yi corresponds to the Tian Guan star, also called Guan Qi; Ren corresponds to the Tian Fu star, also known as Yin Quan; Gui corresponds to the Tian Han star, also called Yin Guang, Yao Guang, and Bei Dao; Gen corresponds to the Yang Shu star of the Tian Shi Yuan, also called Tian Shu; Xun corresponds to the Tai Yi star, also called Yang Xuan; Mao corresponds to the Yang Heng star, also called Tian Li, A Xiang, and Tian Ming Lian Zhen; You corresponds to the Shao Wei star, also called Yang Kai; Hai corresponds to the Tian Huang star, which is the Zi Wei Yuan, also called Tian Men. Among these, Gen corresponds to the Tian Shi Yuan, Hai corresponds to the Zi Wei Yuan, and You corresponds to the Shao Wei Yuan, which exactly matches the directions associated with the four enclosures mentioned earlier.

巳配天屏星，亦曰天堂，曰明堂，曰赤蛇。未配天常星，又曰鬼金。丑配天廚星，亦曰牽牛，曰牛金。庚配天漢星，亦曰陰衡。辛配天乙星，亦曰陰旋。丙配天貴星，亦曰太微陰樞。丁配天柱星，亦曰南極，曰壽星。此四垣諸星，照臨四方，以主庶徵。地法因之，以明其善惡，察其吉凶。所謂天光下臨，地德上載，此之謂也。

The position of Si corresponds to the celestial star Tianping, also known as Tiantang, Mingtang, and Cheshé; the position of Wei corresponds to Tianchang, also called Guijin; the position of Chou corresponds to Tianchu, also called Qianniu and Niujin; the position of Geng corresponds to Tianhan, also called Yinhang; the position of Xin corresponds to Tianyi, also called Yinxuan; the position of Bing corresponds to Tiangui, also called Taimei Yinshu; the position of Ding corresponds to Tianzhu, also called Nanji and Shouxing. These four enclosures have numerous stars that oversee the four directions, governing various signs and omens in the human world. The methods of geomancy use these stars to determine the good and evil, and to assess the auspicious and inauspicious aspects of each direction. It is said, "Heavenly light shines from above to below, and earthly virtue supports from below to above," referring to this. When determining the direction and the site for a burial, one should compare the celestial star corresponding to the mountain with the actual terrain features such as ridges and water, to ensure a complete and accurate judgment.

按陳摶曰：三易穴卦內秘之法，法以太極為太易之統，陰陽為八卦之機，天陰、天陽、地柔、地剛分為四象，少陰、太陽、少陽、太陰、太剛、少柔、少剛、太柔列處八極。天元連山六十四卦，以坎、離、震、兌分歸四仲，以主二十四氣，而周流三百六十五度四分度之一，以成一歲之紀。以章、會、統、元而厯四千六百一十七歲，以成一元之易者，此六十四卦之用也。

According to Chen Tuan, the three Yis are secret methods within the internal structure of the hexagrams. This method takes the Taiji as the overarching principle of the Taiyi, and uses yin and yang as the key to the Eight Trigrams. It divides the heavenly yin, heavenly yang, earthly flexibility, and earthly strength into the four images. It arranges the few yin, sun yang, few yang, great yin, great strength, few flexibility, few strength, and great flexibility at the extreme positions of the eight directions. The Tianyuan "Lianshan" sixty-four hexagrams assign the trigrams Kan, Li, Zhen, and Dui to the four central directions of Zi, Wu, Mao, and You, to govern the twenty-four solar terms. They circulate through three hundred sixty-five and one fourth degrees, forming the measure of a year. Then, using chapters, meetings, unifications, and origins, they calculate layer by layer, spanning four thousand six hundred seventeen years to form a cycle of the Yi—the sixty-four hexagrams' usage in the Lianshan tradition. Each of the three Yis has its own focus, which is the first school.

地元歸藏六十四卦，以冬至、夏至、秋分、春分之日居於四正，以定十二月卦。以月卦分為七十二候，以一水、二火、三木、四金、五土、六水、七火、八木、九金、十土，分隸八方。以六十四卦分定，以推氣朔之會。此六十四卦之用也。

The sixty-four hexagrams of the "Guicang" (a classical divination text) place the four festivals of winter solstice, summer solstice, autumn equinox, and spring equinox at the four cardinal directions of east, west, south, and north, thereby determining the twelve lunar month hexagrams. Then the monthly hexagrams are divided into seventy-two phases, and the order of one water, two fire, three wood, four metal, five earth, six water, seven fire, eight wood, nine metal, ten earth is assigned to the eight directions. Finally, the sixty-four hexagrams are each assigned specific positions to calculate the conjunctions of the solar terms and new moons. This is how the sixty-four hexagrams are used in the "Guicang."

人元周易，以先天、後天分佈方圓卦象。圓布者則幹盡於午中，坤盡於子中，離盡於卯中，坎盡於酉中。陽生於子而極於午，陰生於午而極於子，故其陽在南，其陰在北，所以對待陰陽，櫜鑰天地者，六十四卦之用也。堪輿之所用卦者，不外乎此。

The human origin of the Zhou Changes (I Ching) arranges the Earlier Heaven and Later Heaven into square and circular diagrams respectively. The circular arrangement is as follows: Qian (Heaven) ends at the center of Wu (South), Kun (Earth) ends at the center of Zi (North), Li (Fire) ends at the center of Mao (East), and Kan (Water) ends at the center of You (West). Yang originates from Zi (North) and reaches its peak at Wu (South), while Yin originates from Wu (South) and reaches its peak at Zi (North). Therefore, Yang is located in the South and Yin in the North. Thus, yin and yang are paired oppositely, enclosing and containing heaven and earth within them. This is the method of using the sixty-four hexagrams in the Zhou Changes. The hexagrams used by geomancers do not go beyond these three schools.

以連山而觀天象之盈縮，以歸藏而推氣候之孤虛，以周易而乘地氣之吉凶。用氣以應曜，用陽以相陰，用虛以制殺，用相以迎生。使五運不僭，六氣無倚，三奇當途，四吉順度，龜甲逢生，空亡逢死，九九有氣，六六無侵。於是六氣順成，八卦變化，五行顛倒，大地七寶，其氣順時應，機動神隨，無有端倪矣。

Using the "Lianshan" to observe the fullness and waning of celestial phenomena, using the "Guicang" to investigate the "gū" and "xū" of climate, and using the "Zhouyi" to take advantage of the auspicious and inauspicious energies of the earth. Using qi to correspond with stars, using yang to assist yin, using "xū" to control killing energy, and using "xiāng" to welcome life qi. Ensure that the five movements do not exceed their roles, the six energies are not biased, the three marvels are in place, the four auspicious signs follow their course, the position of the turtle shell is favorable, the position of emptiness is unfavorable, the number nine times nine has qi, and the number six times six is not violated. Thus, the six energies follow in order, the eight trigrams change mutually, the five phases are used in reverse, the seven treasures of the earth respond at the right time, and when the mechanism is activated, the spirits come with it, leaving no trace to be found.

按李籤云：“五氣孤虛旺相，亦從卦氣而分。幹三陽也，以中爻為本卦之體，分上下二爻於甲干，是二陽也。二陽為亢，故為陽之孤氣。坤三也，以中爻為本卦之體，分上下二爻於乙干，是二陰也。二陰為極，故為陰之虛氣。

According to Li's commentary, the five elements' 'solitude', 'vacuity', 'prosperity', and 'conformity' are derived from the hexagram's qi. Qian, being three lines all yang, uses the middle line as the primary body of the hexagram, assigning the upper and lower lines to the Jia stem, which results in two yang lines; two yang lines reach their extreme, hence it is the 'solitude' of yang. Kun, being three lines all yin, uses the middle line as the primary body of the hexagram, assigning the upper and lower lines to the Yi stem, which results in two yin lines; two yin lines reach their extreme, hence it is the 'vacuity' of yin.

震陽卦而陰爻，陽下而陰上也，以中爻為本卦之體，分上下二爻於庚干，一陰一陽交合之象也，故為陽之相氣。巽陰卦而陽爻，陽上而陰下也。以中爻為本卦之體，分上下二氣於辛干，一陰一陽交合之象也，故為陰之相氣。

Zhen is a yang hexagram with many yin lines. Yang is at the bottom and yin is at the top. Using the middle line as the main body of the hexagram, the upper and lower lines are assigned to the Geng stem, forming an image of the union of yin and yang. Therefore, it is the "phase" of yang. Xun is a yin hexagram with many yang lines. Yang is at the top and yin is at the bottom. Using the middle line as the main body of the hexagram, the upper and lower lines are assigned to the Xin stem, also forming an image of the union of yin and yang. Therefore, it is the "phase" of yin. All instances of the union of yin and yang are considered "xiang," while those that are predominantly pure yang or pure yin are called "gu" and "xu."

坎陽卦而陰爻，陽內而陰外也。以中爻為本卦之體，分上下二爻於癸干，是二陰也。二陰為極，故為陰之虛氣。離陰卦而陽爻，陰內而陽外也。以中爻為本卦之體，分上下二爻於壬干，是二陽也，二陽為亢，故為陰之孤氣。

The hexagram Kan is a yang hexagram with many yin lines. Yang is inside and yin is outside. Taking the middle line as the essence of the hexagram, the upper and lower lines are assigned to the dry癸, which are two yin lines. Two yin lines reach their extreme, so it is referred to as the "empty qi" of yin. The hexagram Li is a yin hexagram with many yang lines. Yin is inside and yang is outside. Taking the middle line as the essence of the hexagram, the upper and lower lines are assigned to the dry壬, which are two yang lines. Two yang lines reach their extreme, so it is referred to as the "solitary qi" of yin.

艮陽卦而陰爻，陽上而陰下也。以中爻為本卦之體，分上下二爻於丙干，一陰一陽交合成象也，故為陽之旺氣。兌陰卦而陽爻，陰上而陽下也。以中爻為本卦之體，分上下二爻於丁干，一陰一陽交合象也，故為陰之相氣。是故幹納於甲甲為陽干之首，坤納於乙乙為陰干之首，震納庚，巽納辛，離納壬，兌納丁，坎納癸，艮納丙。陽卦從陽干，陰卦從陰干也。

The trigram Gen is a yang trigram with many yin lines. Yang is above and yin is below, with the middle line serving as the essence of the primary hexagram. The upper and lower lines are assigned to the dry branch Bing, forming an image of the union of yin and yang. Therefore, it is the "prosperous energy" of yang. The trigram Dui is a yin trigram with many yang lines. Yin is above and yang is below, with the middle line serving as the essence of the primary hexagram. The upper and lower lines are assigned to the dry branch Ding, also forming an image of the union of yin and yang. Therefore, it is the "favorable energy" of yin. Thus, the trigram Qian is associated with the dry branch Jia — Jia is the first yang dry branch; the trigram Kun is associated with the dry branch Yi — Yi is the first yin dry branch; the trigram Zhen is associated with Geng, Xun with Xin, Li with Ren, Dui with Ding, Kan with Gui, and Gen with Bing. In summary, yang trigrams follow yang dry branches, and yin trigrams follow yin dry branches. In this way, the relationships of the eight trigrams with the eight dry branches in terms of being isolated, empty, prosperous, or favorable are fixed.

於是天陰、天陽，地剛、地柔，一闢一闔，生成有定，變化無窮。地法用相以制孤，用旺以制虛，避孤虛於本山，乘旺相於異域，以復、姤、臨、遯推天運，以艮、兌、震、巽乘地氣，以甲、丙、戊、庚、壬為陽，分配子、寅、辰、午、申、戌之位，以乙、丁、巳、辛、癸為陰，分配丑、卯、巳、未、酉、亥之位，推排一百二十分金，驗其孤虛旺相之卦，以為就趨之方。中有戊、己一十二位，為龜甲之煞。

Thus, heaven has yin and yang, and earth has strength and softness. One opens and one closes, forming a fixed principle of generation, yet change is endless. The method of geomancy uses "xiang qi" to control "gu," and "wang qi" to control "xu": on the main mountain, avoid gu and xu, and go to other directions to take advantage of wang and xiang; use the hexagrams Fu, Guo, Lin, and Duan to calculate heavenly movement, and use the hexagrams Gen, Dui, Zhen, and Xun to take advantage of earthly qi; take Jia, Bing, Wu, Geng, and Ren as yang, and assign them to the positions of Zi, Yin, Chen, Wu, Shen, and Xu; take Yi, Ding, Ji, Xin, and Gui as yin, and assign them to the positions of Chou, Mao, Si, Wei, You, and Hai (the original text says "Si" instead of "Ji"); based on this, arrange the 120 kinds of gold, and check which category of hexagram—gu, xu, wang, or xiang—they belong to, as the direction to follow. Among them, the twelve positions under Wu and Ji are the "turtle shell"煞.

釋義戊己二干本無正位，寄旺四季，無可以為生之基，故為龜甲，猶龜甲之堅，氣之所不行者，綱紀於支氣而不行乎天，以從地故也。乃十二位地支之中也，有六甲補氣，二十四位為孤虛之空亡甲乙乾坤之天干，氣本孤虛。

The Heavenly Stems Wu and Ji do not have their own proper positions; they merely reside in the four seasons, without a place to generate or establish their foundation, hence they are called "turtle shell" — like the hardness of a turtle shell, the energy cannot pass through. They are governed by the Earthly Branches and do not ascend to the heavens, because they belong to the Earth. When they fall among the twelve Earthly Branches, they are supplemented by the six Jia energies. Among the twenty-four positions, those that are solitary, empty, or lost are the Jia and Yi stems, as well as the Heavenly Stems Qian and Kun, whose energies are inherently inclined towards solitude and emptiness.

又甲子之旬，甲戍、乙亥為補氣；甲午之旬，甲辰、乙巳為補氣；甲辰之旬，甲寅、乙卯為補氣；甲寅之旬，甲子、乙丑為補氣也，故曰日辰不完，故為孤虛。其行地之際，天陽地陰，俱有其氣，故有二十四位也，獨有胎、養、生、旺四氣堪用水、土生申，旺子，胎午，養未。火生寅，旺午，胎子，養丑。木生亥，旺卯，胎酉，養戌。金生巳，旺酉，胎卯，養辰也。

For example, in the Jiazi (甲子) decade, Jiaxu (甲戌) and Yihai (乙亥) are used to supplement the energy; in the Jiawu (甲午) decade, Jiachen (甲辰) and Yisi (乙巳) are used to supplement the energy; in the Jiachen (甲辰) decade, Jiayin (甲寅) and Yimao (乙卯) are used to supplement the energy; in the Jiayin (甲寅) decade, Jiazi (甲子) and Yichou (乙丑) are used to supplement the energy. Therefore, when the day and the heavenly stem are not complete, it is considered as 'guguxu' (孤虚). When it reaches the surface, the heavenly yang and earthly yin each have their own energy, making a total of twenty-four positions. Among these, only the energies of Tai (胎), Yang (养), Changsheng (长生), and Diwang (帝旺) are suitable for use. Water and earth are born in Shen (申), reach their peak in Zi (子), Tai in Wu (午), and Yang in Wei (未); fire is born in Yin (寅), reaches its peak in Wu (午), Tai in Zi (子), and Yang in Chou (丑); wood is born in Hai (亥), reaches its peak in Mao (卯), Tai in You (酉), and Yang in Xu (戌); metal is born in Si (巳), reaches its peak in You (酉), Tai in Mao (卯), and Yang in Chen (辰). The method of selection focuses entirely on these four energies.

而一氣甲子，厥陰生氣司之；二氣甲戌，太陽飛氣司之；三氣甲申，陽明收氣司之；四氣甲午，太陽化氣司之；五氣甲辰，少陽長氣司之；六氣甲寅，少陰舒氣司之。所以演天運，行地氣也。其卦則隨分金位下所屬先天大卦裝排，定其孤虛旺相。先天卦位，幹一、兌二、離三、震四、巽五、坎六、艮七、坤八。分為八卦之位，則乾南、坤北、離東、坎西、巽西南、震東北、兌東南、艮西北。

The first qi Jiazi is governed by the life qi of Jueyin; the second qi Jiaxu is governed by the flying qi of Taiyang; the third qi Jiashen is governed by the gathering qi of Yangming; the fourth qi Jiawu is governed by the transforming qi of Taiyang; the fifth qi Jiachen is governed by the growing qi of Shaoyang; the sixth qi Jiayin is governed by the spreading qi of Shaoyin. These are used to deduce the heavenly movement and the operation of the earthly qi. As for the trigrams, they are arranged according to theEarlier Heaven big trigrams corresponding to each position of the dividing gold. They are determined to be either isolated, empty, prosperous, or favorable. The positions of theEarlier Heaven trigrams are Qian one, Dui two, Li three, Zhen four, Xun five, Kan six, Gen seven, Kun eight. The directions of the eight trigrams are Qian in the south, Kun in the north, Li in the east, Kan in the west, Xun in the southwest, Zhen in the northeast, Dui in the southeast, and Gen in the northwest.

就以幹一、兌二、離三、震四、巽五、坎六、艮七、坤八倍而重之，加於先天八卦之上，為六十四卦。期間遇孤虛旺相四氣消息之，除幹、坤、坎、離四卦不用，餘六十卦，分紀於六十甲子之位，數往者順，知來者逆也。期間遇震、巽、兌、艮成卦六爻者為旺相，值幹、坤、坎、離成卦者為孤虛。即此而推，思過半矣。

By doubling and overlapping the eight trigrams in the order of Qian one, Dui two, Li three, Zhen four, Xun five, Kan six, Gen seven, and Kun eight, they are placed upon the Earlier Heaven Trigrams to form the sixty-four hexagrams. Among these, the four energies of solitude, vacancy, strength, and prominence are used to determine their growth and decline. The four trigrams Qian, Kun, Kan, and Li are excluded, and the remaining sixty hexagrams are assigned to the sixty Jiazi. The sequence is followed in the order of past events to predict future ones. Any hexagram formed with the trigrams Zhen, Xun, Dui, or Gen is considered to be in a state of strength or prominence, while those formed with Qian, Kun, Kan, or Li are considered to be in a state of solitude or vacancy. By following this method, one can understand most of the principles— the selection and rejection of metals in feng shui depend on this key principle.

其五氣之法，以天元六氣、地元五行、人元六甲定其向首長短、闊狹、強弱、布氣、行辰、迎殺、探鬼、操神、收山、用水，以為人利用者，地之宜也。夫形麗於天，氣行於地，其孤虛旺相，亦驗於理而已。

As for the method of the five elements, it uses the heavenly stem six energies, the earthly branch five phases, and the human stem six jia to determine the length, width, strength, and weakness of the front direction, as well as the techniques of distributing energy, moving time, welcoming killing, exploring ghosts, controlling spirits, collecting mountains, and using water, making them available for human use—this is called "what is suitable for the land." The form is manifested in the sky, while the energy flows in the earth; terms such as solitude, emptiness, prosperity, and alignment, in the end, are merely verified by reason.

土圭所以測日定方，立向分金，必上合宿度之真，下準山川之位，功用非小。此而有差，禍福千里。所謂知輕重必準於權衡，為方圓必法於規矩。而地理之於羅經，亦權衡規矩者爾，可不深究其的焉？矧其最微者，莫切於分度。

The soil gnomon is used to measure the shadow of the sun and determine direction; establishing the orientation and dividing the metal must conform to the true numbers of the star mansions and align with the direction of mountains and rivers. Its function is significant. If there is an error here, the difference in fortune and misfortune can be as vast as thousands of miles. Just as one must use a scale to determine weight and a compass and square to make a circle and square, the geomancer's use of the magnetic compass is like the scale and compass. How can it not be thoroughly investigated for accuracy? Moreover, the most subtle aspects involve the measurement of degrees, which is even more critical.

嘗考周天度數三百六十五度四分之一，今羅經悉以平分，每宮三十度，總得三百六十度，少了五度四分度之一。天行每一度計九百四十分，總少四千八百三十五分，計之在地，數千里矣，豈至當之理哉！然宿度以黃道為準，而古今曆黃道度數隨時損益不同，難拘定法。羅經之度，亦當以今之《授時大統曆》黃道度數為準，則與天度不相戾，而為神器之的焉耳。

I once studied the celestial degrees of the entire sky, which amount to 365 and 1/4 degrees. Now, the compass is generally divided evenly, with each sector measuring 30 degrees, totaling only 360 degrees, which is short by 5 and 1/4 degrees. The movement of the sky progresses by 940 parts per degree, so in total, it is missing 4,835 parts. Converted to the surface of the earth, this amounts to several thousand miles. How can this be considered the most appropriate method? However, the degrees of the stars are based on the Yellow Path. The degrees of the Yellow Path in ancient and modern calendars have changed over time, making it difficult to adhere to a fixed method. Therefore, the degrees on the compass should be based on the current Yellow Path degrees from the "Granting the Time Calendar" and the "Great Unity Calendar," so that they do not contradict the celestial degrees and become accurate markings on the sacred instrument. Any newly made compass must first be calibrated according to the current calendar's star degrees before it can be used.

星宿 統天 開僖 會天 授時大統角 十二度九十分 十二度大 十二度大 十二度八十七分亢 九度七十四分 九度大 九度大 九度五十六分氐 十六度三十六分 十六度少 十六度少 十五度四十八分房 五度六十分 五度大 五度大 六度二十七分心 六度四分 六度 六度 七度九十五分

The following table lists the measured degrees of the Yellow Path constellations according to four calendar systems. The columns are in order: Star Mansion, The Tongtian Calendar, The Kaixi Calendar, The Huitian Calendar, and The Shoushi Calendar (also known as the Dati Calendar). For the Horn Mansion: The Tongtian Calendar measures twelve degrees and ninety parts, the Kaixi Calendar measures twelve degrees and a half degree, the Huitian Calendar measures twelve degrees and a half degree, and the Shoushi Calendar measures twelve degrees and eighty-seven parts. For the Neck Mansion: The Tongtian Calendar measures nine degrees and seventy-four parts, the Kaixi Calendar measures nine degrees and a half degree, the Huitian Calendar measures nine degrees and a half degree, and the Shoushi Calendar measures nine degrees and fifty-six parts. For the Root Mansion: The Tongtian Calendar measures sixteen degrees and thirty-six parts, the Kaixi Calendar measures sixteen degrees and less than a half degree, the Huitian Calendar measures sixteen degrees and less than a half degree, and the Shoushi Calendar measures fifteen degrees and forty-eight parts. For the Room Mansion: The Tongtian Calendar measures five degrees and sixty parts, the Kaixi Calendar measures five degrees and a half degree, the Huitian Calendar measures five degrees and a half degree, and the Shoushi Calendar measures six degrees and twenty-seven parts. For the Heart Mansion: The Tongtian Calendar measures six degrees and four parts, the Kaixi Calendar measures six degrees, the Huitian Calendar measures six degrees, and the Shoushi Calendar measures seven degrees and ninety-five parts. (In the table, '大' means a half degree more, and '少' means a half degree less.)

尾 十七度九十分 十八度 十八度 十七度九十五分箕 九度三十三分 九度半 九度半 九度五十九分斗 二十二度半 二十二度大 二十三度 二十三度四十七分牛 八度六分七度 七度 六度九十分女 十度九十五分 十一度 十一度 十一度十二分虛 九度二十八分十五秒 九度少七十九 九度少七十九 九度

Tail mansion: 17.9 degrees according to 《Tong Tian》, 18 degrees according to 《Kai Xi》, 18 degrees according to 《Hui Tian》, and 17.95 degrees according to 《Shou Shi Da Tong》. Winnowing Basket mansion: 9.53 degrees according to 《Tong Tian》, 9.5 degrees according to 《Kai Xi》, 9.5 degrees according to 《Hui Tian》, and 9.59 degrees according to 《Shou Shi Da Tong》. Dipper mansion: 22.5 degrees according to 《Tong Tian》, 22 degrees according to 《Kai Xi》, 23 degrees according to 《Hui Tian》, and 23.47 degrees according to 《Shou Shi Da Tong》. Ox mansion: 8.1 degrees according to 《Tong Tian》, 7 degrees according to 《Kai Xi》, 7 degrees according to 《Hui Tian》, and 6.9 degrees according to 《Shou Shi Da Tong》. Girl mansion: 10.95 degrees according to 《Tong Tian》, 11 degrees according to 《Kai Xi》, 11 degrees according to 《Hui Tian》, and 11.12 degrees according to 《Shou Shi Da Tong》. Emptiness mansion: 9.28 degrees and 15 seconds according to 《Tong Tian》, 9 degrees minus 79 according to 《Kai Xi》, 9 degrees minus 79 according to 《Hui Tian》, and 9 degrees according to 《Shou Shi Da Tong》.

危 十六度一十一分 十六度 十六度 十五度九十五分室 十八度四十五分 十八度少 十八度少 十八度三十二分壁 九度八十分 九度大 九度大 九度三十四分奎 十八度二十一分 十八度 十八度 十七度八十七分婁 十二度七十五分 十二度七十五分 十二度大 十二度三十六分胄 十五度三十八分 十五度少 十五度少 十三度八十一分昴 十一度九分 十一度 十一度 十一度畢 十六度三十分 十六度半 十六度半 十六度半觜 四十六分 半度 半度 二十五分

Wēi Xù: 16 degrees and 11 parts according to 《Tong Tian》, 16 degrees according to 《Kai Xi》, 16 degrees according to 《Hui Tian》, and 15 degrees and 95 parts according to 《Shou Shi Da Tong》. Shì Xù: 18 degrees and 45 parts according to 《Tong Tian》, slightly less than 18 degrees according to 《Kai Xi》, slightly less than 18 degrees according to 《Hui Tian》, and 18 degrees and 32 parts according to 《Shou Shi Da Tong》. Bì Xù: 9 degrees and 80 parts according to 《Tong Tian》, slightly more than 9 degrees according to 《Kai Xi》, slightly more than 9 degrees according to 《Hui Tian》, and 9 degrees and 34 parts according to 《Shou Shi Da Tong》. Kuí Xù: 18 degrees and 21 parts according to 《Tong Tian》, 18 degrees according to 《Kai Xi》, 18 degrees according to 《Hui Tian》, and 17 degrees and 87 parts according to 《Shou Shi Da Tong》. Lóu Xù: 12 degrees and 75 parts according to 《Tong Tian》, 12 degrees and 75 parts according to 《Kai Xi》, slightly more than 12 degrees according to 《Hui Tian》, and 12 degrees and 36 parts according to 《Shou Shi Da Tong》. Wèi Xù (the original text says 'Zhòu Xù'): 15 degrees and 38 parts according to 《Tong Tian》, slightly less than 15 degrees according to 《Kai Xi》, slightly less than 15 degrees according to 《Hui Tian》, and 13 degrees and 81 parts according to 《Shou Shi Da Tong》. Mǎo Xù: 11 degrees and 9 parts according to 《Tong Tian》, 11 degrees according to 《Kai Xi》, 11 degrees according to 《Hui Tian》, and 11 degrees according to 《Shou Shi Da Tong》. Bì Xù: 16 degrees and 30 parts according to 《Tong Tian》, 16 degrees and a half according to 《Kai Xi》, 16 degrees and a half according to 《Hui Tian》, and 16 degrees and a half according to 《Shou Shi Da Tong》. Zī Xù: 46 parts according to 《Tong Tian》, half a degree according to 《Kai Xi》, half a degree according to 《Hui Tian》, and 25 parts according to 《Shou Shi Da Tong》.

參 九度半 九度半 九度半 十度二十八分井 二十九度九十七分 三十度少 三十度半 三十一度鬼 二度三十七分 二度半 二度半 二度十一分柳 十三度三十五分 十三度半 十三度半 星 六度七十五分 六度大 六度大 六度三十一分張 十七度八十六分 十七度大 十七度大 十七度七十九分翼 二十度三十八分 二十度少 二十度少 二十度軫 十九度 十八度大 十八度大 十八度大

Shen Su: Tong Tian nine and a half degrees, Kai Xi nine and a half degrees, Hui Tian nine and a half degrees, Shou Shi Da Tong ten degrees and twenty-eight parts. Jing Su: Tong Tian twenty-nine degrees and ninety-seven parts, Kai Xi thirty degrees minus, Hui Tian thirty degrees and a half, Shou Shi Da Tong thirty-one degrees. Gui Su: Tong Tian two degrees and thirty-seven parts, Kai Xi two and a half degrees, Hui Tian two and a half degrees, Shou Shi Da Tong two degrees and eleven parts. Liu Su: Tong Tian thirteen degrees and thirty-five parts, Kai Xi thirteen and a half degrees, Hui Tian thirteen and a half degrees, Shou Shi Da Tong is missing in the original text, so it is recorded as is without supplementation. Xing Su: Tong Tian six degrees and seventy-five parts, Kai Xi six degrees plus, Hui Tian six degrees plus, Shou Shi Da Tong six degrees and thirty-one parts. Zhang Su: Tong Tian seventeen degrees and eighty-six parts, Kai Xi seventeen degrees plus, Hui Tian seventeen degrees plus, Shou Shi Da Tong seventeen degrees and seventy-nine parts. Yi Su: Tong Tian twenty degrees and thirty-eight parts, Kai Xi twenty degrees minus, Hui Tian twenty degrees minus, Shou Shi Da Tong twenty degrees. Chen Su: Tong Tian nineteen degrees, Kai Xi eighteen degrees plus, Hui Tian eighteen degrees plus, Shou Shi Da Tong eighteen degrees plus.

上黃道度數，自宋《統天曆》至《授時曆》，凡四變，而損益不同，蓋可見矣。然天道三十年必一小變，烏有定法？如冬至日古在牽牛，宋文公時在壁，我朝國初在箕六度，今冬至日在箕四度矣。古今不同，此亦可驗。

The measurements along the Yellow Path have undergone four changes from the Song Dynasty's "Tongtian Calendar" to the "Shoushi Calendar," with varying additions and subtractions, which can be clearly seen. However, the celestial path changes slightly every thirty years, where can there be a fixed rule? For example, the position of the sun on the day of the winter solstice, in ancient times was in the constellation Niutou, during the time of Song Wen Gong it was in the Wall mansion, at the beginning of our dynasty it was six degrees in the Winnowing Basket mansion, and now the winter solstice has already moved to four degrees in the Winnowing Basket mansion. There are differences between ancient and modern times, which can also be verified.

補義周天三百六十五度四分度之一，考之蔡虛齋先生《易經蒙》引云：“天行每一度，計九百四十分度之一，是將一度之分數分作四分之一也。以每度九百四十分分之為四分，則每分該二百三十五分而得之其四分之一也。以周天總數三百六十五度四分度之一之分數計之，共得三十四萬三千三百三十五分，是天度分數之總也。

The celestial circle comprises 365 and 1/4 degrees. According to Cai Qing's "Yijing Mengyin," the sky moves one degree at a time, which is divided into 940 parts. This further divides each degree into four parts, making each part 235 parts. When calculating the total number of parts for the entire celestial circle of 365 and 1/4 degrees, it results in 343,335 parts in total. In other words, the细分 of each degree on the compass must be evenly distributed based on this total number of parts to avoid discrepancy with the actual movement of the sky.

一說地本靜，故平分三十度永定以測地。不知地附於天，故土圭之制，測日以準，則度數亦當準之於天。先正云：“俯察地理，必先仰觀天文，然後可以操造化之柄。”未有背天時能明地理者，以負人和者。

There is another view which holds that the earth is originally still, so the entire circle was evenly divided into thirty degrees per palace, fixed permanently for measuring the earth. But this fails to recognize that the earth depends on the heavens, so the making of the gnomon is based on measuring the sun. Therefore, the degrees on the compass should also be based on the heavens. The ancients said: "To investigate the geography, one must first observe the heavenly phenomena, then one can grasp the key to the workings of nature." There has never been anyone who departed from the heavenly timing and yet understood the geography, for that would be a betrayal of humanity.

按羅經二十四位，子為正北，壬、癸輔之。午為正南，丙、丁輔之。卯為正東，甲、乙輔之。酉為正西，庚、辛輔之。子、午、卯、酉即文王後天坎、離、震、兌四方至正之位也。幹、坤、艮、巽為四隅，總以八干十二支，即東方甲、卯、乙、辰，而卯居正中；南方巳、丙、午、丁、未，而午居正中；西方申、庚、酉、辛、戌，而酉居正中；北方亥、壬、子、癸、丑，而子居正中。此大中至正之理，天地至極之位，萬古之方。

According to the twenty-four directions on the compass: Zi is due north, with Ren and Gui supporting on both sides; Wu is due south, with Bing and Ding supporting on both sides; Mao is due east, with Jia and Yi supporting on both sides; You is due west, with Geng and Xin supporting on both sides. Zi, Wu, Mao, and You are the four cardinal directions of the Later Heaven hexagrams Kan, Li, Zhen, and Dui, which are the most central positions. Qian, Kun, Gen, and Xun are the four corners. Altogether, using the eight heavenly stems and twelve earthly branches: the east is Jia, Mao, Yi, and Chen, with Mao in the center; the south is Si, Bing, Wu, Ding, and Wei, with Wu in the center; the west is Shen, Geng, You, Xin, and Xu, with You in the center; the north is Hai, Ren, Zi, Gui, and Chou, with Zi in the center. This is the principle of great centralization and correctness, the ultimate directions of heaven and earth, unchanging through the ages. When using the compass, one must first determine these four cardinal and four corner directions, and only then can one discuss deviation and alignment. The original text lists only four directions for the east, Jia, Mao, Yi, and Chen, which is not consistent with the five directions of other sides. It is recorded as is without supplementation.

但後來浮針之制，較之日影，南望南斗，北對樞星，其針頗偏於丙，蓋非南北之偏，寔浮針之畏正火而然也。故立縫針以準天地之正位，是以針合天地之位也。後人遂杜撰其說，附會多端，或以節氣為言，或以漏刻為喻，愈辨愈支。苟以浮針所指為正南北，則是將天地方位移轉以就其針矣，豈有是理也哉！詳見金精針說。

But later made floating needles were compared with the shadow of the sun—looking south toward the Southern Dipper and facing north toward the North Star—the needle head was somewhat inclined toward the Bing position. This was not because the north and south of heaven and earth were themselves skewed, but rather because the floating needle feared the fire of due south. Therefore, another type of needle called the "sewing needle" was established to correct the true directions of heaven and earth, meaning using the needle to conform to the positions of heaven and earth. Later people fabricated many explanations, forcing connections: some used the twenty-four solar terms, others used water clocks as metaphors, and the more they argued, the more confused they became. If one takes the direction indicated by the floating needle as due south and due north, that would be moving the positions of heaven and earth to conform to this needle, which is utterly unreasonable! A detailed analysis can be found in the "Discourse on the Golden Essence Needle."

按廖金精曰：“古者辨方位，樹八尺之臬，而度其日出之影，以正東西。又參日中之影與極星以正南北。《周禮匠人》之制度繁難，智者用周公指南車之制，規以木盤，外書二十四位，中為水池，滴水於其間，以磁石磨鋒浮於水面，則指南。然後以臬影較之，則不指正南，常偏丙位，故以丙午間對針，則二十四位皆得其正矣。用此以代樹臬，可謂簡便，眞萬古不滅之良法也。昧者罔知，嘵嘵致辯，何其謬哉！”此出《洩天機》。

According to Liao Jinjing, ancient people determined directions by erecting a pole eight feet high and measuring the shadow of the sunrise to correct east and west. They also referred to the shadow at noon and the position of the North Star to correct north and south. The system described in the "Rites of Zhou: The Official Craftsman" is complicated, so the wise adopted the principle of Zhou Gong's south-pointing chariot: making a circular wooden disc with the twenty-four directions marked around the outside, a water tank in the center, and a needle sharpened with magnetite floating on the water surface, which points south. Then they compared the shadow of the gnomon with the needle, finding that it did not point directly south but often leaned toward Bing. Therefore, they aligned the needle between Bing and Wu, and the twenty-four directions became properly aligned. This method replaced the gnomon for measuring shadows and is said to be convenient and an enduring method for all time. The foolish do not understand this and keep arguing endlessly, how absurd! This passage is from "Xie Tianji".

詳義 按《周禮匠人》置臬以度日影，辨方正位之法。水地以垂謂先以水平也，四方皆平，乃造。營造，於營造處四角立四柱，於四柱用垂繩以正柱。柱正，然後以水平之法，遙視柱高下。高下定，則知地之高下，然後平高就下，則地乃平也。

The detailed explanation: According to the "Rites of Zhou · Records of the Master Craftsman," the method of using vertical poles to measure the shadow of the sun and determine directions. "Watering the earth to level it" means first using the method of water level to make the ground flat: only after all four sides are level can construction begin. When building, four pillars are set up at the four corners of the construction site, and a plumb line is used on each pillar to check if the pillar is vertical. After the pillars are vertical, the height of each pillar is checked from a distance using the water level method; once the heights are determined, the elevation of the ground is known, and then the high areas are cut down and the low areas are filled up, resulting in a flat ground.

置臬以垂，視以景臬，柱也。於所平之地中央，樹八尺之木以為表。表界其四面之中，及四稜，垂八繩以等之。繩皆附表則正。然後視表之景。表必八尺者，日從上向下八萬里，故以八尺為法。為規識日出之景，與日入之景自日出而畫其影端，以至日入則為規矣。平取其隔影之端，中屈之以望表，則南北正。南北正則東西正矣，晝參諸日中之景候其日之影最短處以望表，則正南也，夜考之極星晝既定南極，夜又定北極以參之，以正朝夕朝夕即東西也。言東西可以兼南北。

"Set up a vertical pole to cast a shadow and observe it." The pole is a vertical stick. On a level ground in the center, a pole eight chi high is erected as the gnomon. At the middle of each side and along the edges of the pole, eight ropes are hung to align it. The ropes are tightly attached to the pole, ensuring it is vertical. Then the shadow of the pole is observed. The pole must be eight chi high because the sun travels eight ten-thousand li from above, so eight chi is taken as the standard. "To mark the shadow at sunrise and sunset" means that from sunrise, the position of the end of the shadow is drawn until sunset, forming a circular arc. By connecting the ends of the shadows and folding the line in half to look at the pole, the direction of north and south is determined. Once north and south are aligned, east and west are also aligned. During the day, the shadow at noon is used as a reference—waiting for the shortest shadow to look at the pole, which indicates true south. At night, the North Star is observed—since the South Pole has already been determined during the day, the North Star is used to verify and correct the direction of east and west. Here, the mention of east and west also includes north and south.

候日出之影，度其臬端，以知西；候日入之影，度其臬端，以知東。晝日參候其臬影之最短處，為日中，以望臬，臬端則是正南；夜於臬南以望臬端，考之極星，則是正北。葢極星居北不移，故取正北。上樹臬測影以定四方之法。今得西山眞先生武庫所著公劉相陰陽圖，謹按其式，具圖以備考焉。

By observing the shadow at sunrise and measuring the direction it points on the sundial, one can determine the direction of the west. By observing the shadow at sunset and measuring the direction it points on the sundial, one can determine the direction of the east. During the day, by checking the shortest shadow, one can find the noon. Facing the sundial, the direction pointed by the sundial's tip is due south. At night, by looking toward the sundial's tip from the south side of the sundial and referring to the North Star, one can determine due north. Since the North Star remains fixed in the north, it is used to determine due north. The above is the method of using a vertical gnomon to measure shadows and determine the four cardinal directions. Now, having obtained the diagram of the Yin and Yang from the book Wu Ku by the esteemed scholar Xizheng Zhen Dexiu of the Western Mountain, I have carefully followed its pattern to draw the diagram here for reference and verification.

《經》云“既景乃崗”，又云“相其陰陽，度其夕陽。”《傳》云“景，測日景以正四方也。相，視也。陰陽，向背、寒暖之宜也。山西曰夕陽。”嚴氏曰：“豳在梁山西，公劉相此地以建豳居也。”

The Book of Poetry, Great Odes, Gong Liu says, "After measuring the hilltops," and also says, "Observing the yin and yang, measuring the western slope." The Mao Transmission explains that "jing" refers to measuring the shadow of the sun to correct the directions; "xiang" means to observe; "yin and yang" refers to the suitability of the backside and the coolness and warmth; the western side of the mountain is called "xiyang." Yan says that the region of Binxian is to the west of Liang Mountain, and Gong Liu surveyed this area to build the settlement of Binxian. This shows that observing yin and yang and distinguishing directions was already practiced in the Three Dynasties.