五行者，水火木金土也。五行即阴阳之质，阴阳即五行之气，气非质不立，质非气不
行。行也者，所以行阴阳之气也。朱子曰∶五行质具于地而气行于天。其实元初，只一太
极，一分为二，二分为四。天得一个四，地得一个四，又各有一个太极行乎其中，便是两其
五行而已。故河洛图书具阴阳之象，分左右中前后以列五行生成之数焉。先儒曰∶天地
者，阴阳对待之定体；一二三四五六七八九十者，阴阳流行之次序。对待非流行不能变化，
流行非对待不能自行，此五行所以流行于天地中而为用也。故大挠察天地之阴阳，立十干
十二支以着日月之象。十干以应日，天之五行也，甲阳乙阴为木，丙阳丁阴为火，戊阳己阴
为土，庚阳辛阴为金，壬阳癸阴为水；十二支以应月，地之五行也，子阳亥阴曰水，午阳巳阴
曰火，寅阳卯阴曰木，申阳酉阴曰金，辰戌阳丑未阴曰土。干支出而六甲成，运气分而时序
定。所谓天地相临，阴阳相合，而生成之道存乎其中。故五行之化无乎不在，精浮于天则
为五星∶水曰辰星，火曰荧惑，木曰岁星，金曰太白，土曰镇星。形成于地则为五方∶水位于
北，火位于南，木位于东，金位于西，土位于中。其为四时∶则木王于春，火王于夏，金王于
秋，水王于冬，土王于四季。其为六气∶则木之化风，火之化暑与热，土之化湿，金之化燥，
水之化寒。其为名目∶则水曰润下，火曰炎上，木曰曲直，金曰从革，土爰稼穑。其为功用∶
则水主润，火主 ，木主敷，金主敛，土主溽。其为形体∶则水质平，火质锐，木质长，金质
方，土质圜。其为赋性∶则水性寒，火性热，木性温，金性清，土性蒸。其为五帝∶则木曰太
，火曰炎帝，土曰黄帝，金曰少 ，水曰颛顼。其为五神∶则木曰勾芒，火曰祝融，土曰后
土，金曰蓐收，水曰玄冥。其为五则∶则火以应衡，水以应权，木以应规，金以应矩，土以应
绳。至若五谷、五果、五畜、五音、五色、五臭、五味、五脏之类，无非属于五行也。又如五行
气数之异，阴阳之辨，亦有所不同者。若以气言时之序，则曰木火土金水，如木当春令为阳
稚，火当夏令为阳盛，金当秋令为阴稚，水当冬令为阴盛，是木火为阳，金水为阴也。若以
数言生之序，则曰水火木金土，如天一生水为阳稚，天三生木为阳盛，地二生火为阴稚，地
四生金为阴盛，是水木为阳，而火金为阴也。此外如洛书、乐律、刘向、班固等义，序各不
同，无非变化之道，而运用之机，亦无过生克之理耳。故自其相生者言，则水以生木，木以
生火，火以生土，土以生金，金以生水。自其相克者言，则水能克火，火能克金，金能克木，
木能克土，土能克水。自其胜复者言，则凡有所胜，必有所败，有所败，必有所复，母之败
也，子必救之。如水之太过，火受伤矣，火之子土，出而制焉；火之太过，金受伤矣，金之子
水，出而制焉；金之太过，木受伤矣，木之子火，出而制焉；木之太过，土受伤矣，土之子金，
出而制焉；土之太过，水受伤矣，水之子木，出而制焉。盖造化之几，不可无生，亦不可无
制。无生则发育无由，无制则亢而为害。生克循环，营运不息，而天地之道，斯无穷已。第
人知夫生之为生，而不知生中有克；知克之为克，而不知克中有用；知五之为五，而不知五
者之中，五五二十五，而复有互藏之妙焉。所谓生中有克者，如木以生火，火胜则木乃灰
烬；火以生土，土胜则火为扑灭；土以生金，金胜则土无发生；金以生水，水胜则金为沉溺；
水以生木，木胜则水为壅滞。此其所以相生者，实亦有所相残也。所谓克中之用者，如火
之炎炽，得水克而成既济之功；金之顽钝，得火克而成 炼之器；木之曲直，得金克而成芟
削之材；土之旷墁，得木克而见发生之化；水之泛滥，得土克而成堤障之用。此其所以相克
者，实又所以相成也。而五常之德亦然，如木德为仁，金德为义，火德为礼，水德为智，土德
为信。仁或失于柔，故以义断之；义或失于刚，故以礼节之；礼或失于拘，故以智通之；智或
失于诈，故以信正之。是皆生克反用之道也。所谓五者之中有互藏者，如木之有津，木中
水也；土之有泉，土中水也；金之有液，金中水也；火之熔物，火中水也。夫水为造化之原，
万物之生，其初皆水，而五行之中，一无水之不可也。火之互藏，木钻之而见，金击之而见，
石凿之而见；惟是水中之火，人多不知，而油能生火，酒能生火，雨大生雷，湿多成热，皆是
也。且火为阳生之本，虽若无形，而实无往不在，凡属气化之物，非火不足以生，故五行之
中，一无火之不可也。土之互藏，木非土不长，火非土不荣，金非土不生，水非土不蓄，万物
生成，无不赖土，而五行之中，一无土之不可也。木之互藏，生于水，植于土，荣于火，成于
金。凡发生之气，其化在木。即以人生而言，所衣所食皆木也，得木则生，失木则死，故曰
人生于寅，寅者阳木之位也。由人而推，则凡动植之类，何非阳气？而又何非木化？此五
行万物之中，一无木之不可也。金之互藏，产于山石，生诸土也；淘于河沙，隐诸水也；草有
汞，木有 ，藏于木也；散可结；柔可刚，化于火也。然金之为用，坚而不毁，故易曰干为金。
夫干象正圆，形如瓜卵，柔居于中，刚包乎外。是以天愈高而愈刚，地愈下而愈刚。故始皇
起坟骊山，深入黄泉三百丈，凿之不入，烧之不毁。使非至刚之气，真金之体，乃能若是其
健而营运不息乎？故凡气化之物，不得金气，无以坚强。所以皮壳在外而为捍卫者，皆得
干金之气以固其形。此五行万物之中，一无金之不可也。由此而观，则五行之理，交互无
穷。故甲丙戊庚壬，天之阳干也，而交于地之子寅辰午申戌；乙丁己辛癸，天之阴干也，而
交于地之丑亥酉未巳卯。天地五行挨相交配，以天之十而交于地之十二，是于五行之中，
各具五行，乃成六十花甲；由六十花甲而推于天地万物，其变可胜言哉？然而变虽无穷，总
不出乎阴阳；阴阳之用，总不离乎水火。所以天地之间，无往而非水火之用。欲以一言而
蔽五行之理者，曰乾坤付正性于坎离，坎离为乾坤之用耳。
五行，指的是水、火、木、金、土这五种物质。五行是阴阳的实体（构成物质的基础），阴阳是五行的气机（运动变化的功能）。气如果没有实体就无法立足，实体如果没有气就无法运行。“行”的意思，就是用来运行阴阳之气的。朱熹说：“五行的实体存在于大地，而五行的气机运行于天空。”其实追溯本源，起初只有一个太极，太极一分为二（即阴阳），二再分为四象。天得到一个四象，地也得到一个四象，天地之中又各自包含一个太极在运行，这就构成了两重五行（天地各备五行）的道理。所以河图洛书等易学图谱都具备阴阳的象征，分左右、中、前、后来排列五行生成的数理。先儒说：“天地，是阴阳相对固定的形体；一至十的数字，是阴阳运行的次序。”相对静止的形体如果没有运行的气机就不能产生变化，运行的气机如果没有相对的形体就不能自行运作，这就是五行所以在天地之间流行并发挥作用的原因。因此，大挠观察天地的阴阳，创立了十天干和十二地支以象征日月运行。十天干对应太阳，代表天的五行：甲为阳乙为阴属木，丙为阳丁为阴属火，戊为阳己为阴属土，庚为阳辛为阴属金，壬为阳癸为阴属水；十二地支对应月亮，代表地的五行：子为阳亥为阴属水，午为阳巳为阴属火，寅为阳卯为阴属木，申为阳酉为阴属金，辰戌为阳丑未为阴属土。天干地支推出后，六十甲子便形成了，运气区分后，时序也就确定了。这就是所谓天地相临，阴阳相合，而万物生成的道理存在于其中。
所以五行的化育无处不在：精气浮游于天就成为五星：水叫辰星，火叫荧惑星，木叫岁星，金叫太白星，土叫镇星。形成于地就成为五方：水位于北方，火位于南方，木位于东方，金位于西方，土位于中央。对应四季：则木旺于春季，火旺于夏季，金旺于秋季，水旺于冬季，土旺于四季（每季最后十八天）。对应六气：则木的化气为风，火的化气为暑与热，土的化气为湿，金的化气为燥，水的化气为寒。对应的名目：则水性润下，火性炎上，木性曲直，金性从革，土性稼穑。对应的功用：则水主滋润，火主温热（原文缺字，据义补为温/热），木主生发舒展，金主收敛，土主湿润厚重。对应的形体：则水质平正，火质尖锐，木质修长，金质方正，土质圆浑。对应的本性：则水性寒，火性热，木性温，金性清肃，土性蒸腾。对应的五帝：则木曰太皞，火曰炎帝，土曰黄帝，金曰少皞，水曰颛顼。对应的五神：则木曰勾芒，火曰祝融，土曰后土，金曰蓐收，水曰玄冥。对应的五常法则：则火对应衡（平衡），水对应权（权衡），木对应规（圆规），金对应矩（方矩），土对应绳（墨线）。至于五谷、五果、五畜、五音、五色、五臭、五味、五脏之类，无不归属于五行。
又如五行气数的差异，阴阳的辨别，也有不同的说法。如果从“气”的角度讲时序，则顺序是木、火、土、金、水。如木当春令为阳之稚弱，火当夏令为阳之盛壮，金当秋令为阴之稚弱，水当冬令为阴之盛壮，这是木火属阳，金水属阴。如果从“数”的角度讲生成次序，则顺序是水、火、木、金、土。如天一生水为阳之稚弱，天三生木为阳之盛壮，地二生火为阴之稚弱，地四生金为阴之盛壮，这是水木属阳，而火金属阴。此外如洛书、乐律、刘向、班固等人的义理，排序各不相同，无非都是变化的道理，而其运用的机理，也不过是生克的原理罢了。
所以从其相生方面来说，则是水生木，木生火，火生土，土生金，金生水。从其相克方面来说，则是水能克火，火能克金，金能克木，木能克土，土能克水。从其胜复（报复性调节）方面来说，则凡是有所胜（克制），必有所败（受损），有所败，必有所复（报复）。母行受损，子行必定救助它。如水气太过，火气受伤了，火之子土气，出来制约水气；火气太过，金气受伤了，金之子水气，出来制约火气；金气太过，木气受伤了，木之子火气，出来制约金气；木气太过，土气受伤了，土之子金气，出来制约木气；土气太过，水气受伤了，水之子木气，出来制约土气。大概造化的机制，不可没有生，也不可没有制。没有生，就没有发育的来源；没有制，就会亢盛而为害。生克循环，运行不息，而天地的道理，由此无穷无尽。只是人们只知道生是生，而不知道生中有克；知道克是克，而不知道克中有用；知道五是五，而不知道五者之中，五五二十五，还有互藏的奥妙。
所谓“生中有克”，如木生火，火过胜则木化为灰烬；火生土，土过胜则火被扑灭；土生金，金过胜则土无发生之机；金生水，水过胜则金被沉溺；水生木，木过胜则水被壅滞。这就是之所以相生，实则也有所相残的原因。所谓“克中之用”，如火焰炽盛，得水来克而成既济之功（水火调和）；金质顽钝，得火来克而成冶炼之器；木之曲直，得金来克而成修剪之材；土地旷漫，得木来克而见发生之化（树木扎根疏松土壤）；水势泛滥，得土来克而成堤障之用。这就是之所以相克，实则又是相辅相成的原因。五常之德也是如此，如木德为仁，金德为义，火德为礼，水德为智，土德为信。仁爱若失于柔弱，故以义来裁断；义若失于刚强，故以礼来节制；礼若失于拘谨，故以智来通达；智若失于狡诈，故以信来匡正。这些都是生克反向运用的道理。
所谓“五者之中有互藏”，如木中含有津液，木中藏有水；土中含有泉水，土中藏有水；金中含有液体，金中藏有水；火能熔化物体，火中藏有水。水是造化的本源，万物的生长，起初都是水，而在五行之中，无一物无水是不可的。火的互藏，钻木可见，击金可见，凿石可见；只有水中的火，人们大多不知道，而油能生火，酒能生火，大雨生雷，湿气多成热，都是这一原理。而且火是阳气产生的根本，虽然看似无形，但实际无处不在，凡属于气化之物，没有火不足以产生，所以在五行之中，无一物无火是不可的。土的互藏，木非土不生长，火非土不繁荣，金非土不生发，水非土不蓄积，万物生成，无不依赖土，所以在五行之中，无一物无土是不可的。木的互藏，生于水，植于土，荣于火，成于金。凡发生之气，其化育在于木。就人生而言，所穿所吃皆属木类，得到木气则生，失去木气则死，所以说人生于寅，寅是阳木的位置。由人推及万物，则凡动植物的类别，何尝不是阳气？又何尝不是木的化育？这在五行万物之中，无一物无木是不可的。金的互藏，产于山石，生于土中；淘于河沙，隐于水中；草含有汞，木含有树脂，藏于木中；散可凝结，柔可变刚，化于火中。然而金的作用，坚硬而不毁，所以《易经》说乾卦为金。乾卦象征正圆，形状如瓜卵，柔居于中间，刚包裹在外面。所以天越高越刚，地越低越刚。所以秦始皇在骊山起坟，深入黄泉三百丈，凿之不入，烧之不毁。如果不是至刚之气，真金的体质，怎么能如此健壮且运行不息呢？所以凡气化之物，不得金气，无法坚强。所以皮壳在外作为捍卫的，都是得乾金之气来巩固其形体。这在五行万物之中，无一物无金是不可的。
由此看来，五行的道理，交互无穷。所以甲丙戊庚壬，是天的阳干，而与地的子寅辰午申戌相交；乙丁己辛癸，是天的阴干，而与地的丑亥酉未巳卯相交。天地五行挨次相交配合，以天的十个干与地的十二个支相配，于是在五行之中，各具五行，才形成了六十花甲；由六十花甲推及天地万物，其变化岂能说尽？然而变化虽无穷，总不出乎阴阳；阴阳的作用，总不离乎水火。所以天地之间，无处不是水火的作用。想用一句话来概括五行的道理，那就是：乾坤赋予坎离以正性，坎离是乾坤的作用罢了。
Wu Xing (Five Phases), refers to Water, Fire, Wood, Metal, and Earth. Wu Xing are the substance of Yin and Yang, while Yin and Yang are the Qi (vital energy) of Wu Xing. Qi cannot stand without substance, and substance cannot move without Qi. "Xing" (Phase/Movement) means that which moves the Qi of Yin and Yang. Zhu Xi said: "The substance of Wu Xing resides in the Earth, while its Qi moves in the Heaven." In truth, at the very beginning, there was only one Taiji (Supreme Ultimate). Taiji divided into two (Yin and Yang), and two divided into four (Four Symbols). Heaven received one set of four symbols, and Earth received another set, each containing a Taiji operating within it; this constitutes the principle of "two sets of Wu Xing" (Heaven and Earth each possessing the Five Phases). Thus, the He Tu (River Map) and Luo Shu (Lo River Scroll) possess images of Yin and Yang, arranging the numbers of generation and completion of Wu Xing according to left, right, center, front, and back. Ancient scholars said: "Heaven and Earth are the fixed forms of opposing Yin and Yang; the numbers one through ten are the sequence of flowing Yin and Yang." Fixed opposition cannot change without flow, and flow cannot operate independently without fixed opposition. This is why Wu Xing flows within Heaven and Earth to exert its function. Therefore, Da Ran observed the Yin and Yang of Heaven and Earth, established the Ten Heavenly Stems and Twelve Earthly Branches to manifest the images of the sun and moon. The Ten Heavenly Stems correspond to the Sun, representing the Wu Xing of Heaven: Jia (Yang) and Yi (Yin) belong to Wood; Bing (Yang) and Ding (Yin) belong to Fire; Wu (Yang) and Ji (Yin) belong to Earth; Geng (Yang) and Xin (Yin) belong to Metal; Ren (Yang) and Gui (Yin) belong to Water. The Twelve Earthly Branches correspond to the Moon, representing the Wu Xing of Earth: Zi (Yang) and Hai (Yin) are Water; Wu (Yang) and Si (Yin) are Fire; Yin (Yang) and Mao (Yin) are Wood; Shen (Yang) and You (Yin) are Metal; Chen and Xu (Yang) and Chou and Wei (Yin) are Earth. When Stems and Branches are combined, the Sixty Jiazi cycle is formed; when Luck (Yun) is distinguished, the seasonal order is determined. This is what is meant by Heaven and Earth approaching each other, Yin and Yang combining, and the way of generation existing within them.
Therefore, the transformation of Wu Xing is everywhere: Essence floating in Heaven becomes the Five Planets: Water is Chen Xing (Mercury), Fire is Ying Huo (Mars), Wood is Sui Xing (Jupiter), Metal is Tai Bai (Venus), and Earth is Zhen Xing (Saturn). Formed on Earth, they become the Five Directions: Water is located in the North, Fire in the South, Wood in the East, Metal in the West, and Earth in the Center. Corresponding to the Four Seasons: Wood dominates in Spring, Fire in Summer, Metal in Autumn, Water in Winter, and Earth in the transition periods of the four seasons. Corresponding to the Six Qi: Wood transforms into Wind, Fire into Heat and Summer-heat, Earth into Dampness, Metal into Dryness, and Water into Cold. Corresponding to their names: Water is described as moistening and descending, Fire as flaming upward, Wood as bending and straightening, Metal as yielding and changing, and Earth as sowing and reaping. Corresponding to their functions: Water governs moistening, Fire governs warming, Wood governs spreading and generating, Metal governs gathering and condensing, and Earth governs humidification and heaviness. Corresponding to their forms: Water's form is level, Fire's is sharp, Wood's is long, Metal's is square, and Earth's is round. Corresponding to their nature: Water is cold, Fire is hot, Wood is warm, Metal is clear/pure, and Earth is steaming/warm. Corresponding to the Five Emperors: Wood is Tai Hao, Fire is Yan Di, Earth is Huang Di, Metal is Shao Hao, and Water is Zhuan Xu. Corresponding to the Five Deities: Wood is Gou Mang, Fire is Zhu Rong, Earth is Hou Tu, Metal is Ru Shou, and Water is Xuan Ming. Corresponding to the Five Rules: Fire corresponds to Heng (balance), Water to Quan (weight/measurement), Wood to Gui (compass), Metal to Ju (square/ruler), and Earth to Sheng (plumb line). As for the Five Grains, Five Fruits, Five Livestock, Five Tones, Five Colors, Five Odors, Five Flavors, and Five Zang Organs, none do not belong to Wu Xing.
Furthermore, regarding the differences in Wu Xing Qi and numbers, and the distinction of Yin and Yang, there are varying interpretations. If speaking from the perspective of Qi and temporal sequence, the order is Wood, Fire, Earth, Metal, Water. For example, Wood during Spring command is Young Yang, Fire during Summer command is Full Yang, Metal during Autumn command is Young Yin, and Water during Winter command is Full Yin. Thus, Wood and Fire are Yang, while Metal and Water are Yin. If speaking from the perspective of Number and generative sequence, the order is Water, Fire, Wood, Metal, Earth. For example, Heaven generates One Water (Young Yang), Heaven generates Three Wood (Full Yang), Earth generates Two Fire (Young Yin), and Earth generates Four Metal (Full Yin). Thus, Water and Wood are Yang, while Fire and Metal are Yin. Besides, such theories as those in the Luo Shu, music laws, Liu Xiang, and Ban Gu have different sequences, all being merely the Way of Change. The mechanism of application does not exceed the principle of Generation and Restriction.
Thus, speaking from the aspect of Mutual Generation: Water generates Wood, Wood generates Fire, Fire generates Earth, Earth generates Metal, and Metal generates Water. Speaking from the aspect of Mutual Restriction: Water restricts Fire, Fire restricts Metal, Metal restricts Wood, Wood restricts Earth, and Earth restricts Water. Speaking from the aspect of Victory and Repayment (compensatory regulation): Wherever there is victory (restriction), there must be defeat (damage); wherever there is defeat, there must be repayment. When the Mother element is defeated, the Child element must rescue it. If Water is excessive, Fire is injured; then Fire's child, Earth, comes out to control Water. If Fire is excessive, Metal is injured; then Metal's child, Water, comes out to control Fire. If Metal is excessive, Wood is injured; then Wood's child, Fire, comes out to control Metal. If Wood is excessive, Earth is injured; then Earth's child, Metal, comes out to control Wood. If Earth is excessive, Water is injured; then Water's child, Wood, comes out to control Earth. Essentially, the mechanism of creation cannot lack Generation, nor can it lack Restriction. Without Generation, there is no source for development; without Restriction, hyperactivity leads to harm. Generation and Restriction cycle endlessly, and the Way of Heaven and Earth is thus infinite. However, people know that Generation is Generation, but do not know that Restriction exists within Generation; they know that Restriction is Restriction, but do not know that Utility exists within Restriction; they know that Five is Five, but do not know that within the Five, there are five times five twenty-five, and further, the subtlety of Mutual Storage.
What is meant by "Restriction within Generation"? For example, Wood generates Fire; if Fire becomes too victorious, Wood turns to ash. Fire generates Earth; if Earth becomes too victorious, Fire is extinguished. Earth generates Metal; if Metal becomes too victorious, Earth has no opportunity to generate. Metal generates Water; if Water becomes too victorious, Metal is submerged. Water generates Wood; if Wood becomes too victorious, Water is blocked. This is why, although they generate each other, they also destroy each other. What is meant by "Utility within Restriction"? For instance, blazing Fire is controlled by Water to achieve the state of Ji Ji (Successful Completion/Harmony); stubborn Metal is refined by Fire to become a vessel; crooked Wood is trimmed by Metal to become useful timber; barren Land is cultivated by Wood to reveal its generative transformation; overflowing Water is contained by Earth to serve as a dike. This is why, although they restrict each other, they actually complete each other. The Virtues of the Five Constants are also like this: Wood virtue is Ren (Benevolence), Metal virtue is Yi (Righteousness), Fire virtue is Li (Propriety), Water virtue is Zhi (Wisdom), and Earth virtue is Xin (Trustworthiness). If Benevolence loses itself in softness, Righteousness cuts it off; if Righteousness loses itself in rigidity, Propriety regulates it; if Propriety loses itself in拘谨 (rigidity/stiffness), Wisdom penetrates it; if Wisdom loses itself in deceit, Trustworthiness corrects it. These are all ways of using Generation and Restriction inversely.
What is meant by "Mutual Storage within the Five"? For example, Wood contains fluid, meaning Water is stored in Wood; Earth contains springs, meaning Water is stored in Earth; Metal contains liquid, meaning Water is stored in Metal; Fire melts objects, meaning Water is stored in Fire. Water is the origin of creation; the birth of all things begins with Water, and among the Five Phases, nothing is possible without Water. The mutual storage of Fire is seen by drilling wood, striking metal, or chiseling stone. However, the Fire within Water is unknown to most people. Oil producing fire, wine producing fire, heavy rain producing thunder, and excess dampness generating heat are all examples of this. Moreover, Fire is the root of Yang generation. Although seemingly formless, it is present everywhere. All things undergoing Qi transformation require Fire to be generated; thus, among the Five Phases, nothing is possible without Fire. The mutual storage of Earth: Wood does not grow without Earth, Fire does not flourish without Earth, Metal does not generate without Earth, Water does not accumulate without Earth. The generation of all things relies on Earth; thus, among the Five Phases, nothing is possible without Earth. The mutual storage of Wood: Born from Water, planted in Earth, flourishing in Fire, completed by Metal. The Qi of generation transforms in Wood. Regarding human life, what we wear and eat are all related to Wood. Obtaining Wood Qi brings life, losing it brings death. Hence it is said, "Humans are born in Yin," where Yin represents the position of Yang Wood. Extending from humans to all things, are all moving and non-moving beings not Yang Qi? And are they not transformations of Wood? Thus, among the myriad things of Wu Xing, nothing is possible without Wood. The mutual storage of Metal: Produced in mountains and rocks, born in Earth; washed in river sands, hidden in Water; grass contains mercury, wood contains resin, hidden in Wood; scattered can结 (condense), soft can become hard, transformed by Fire. However, the use of Metal is firm and unbreakable. Thus, the I Ching states that Qian (Heaven) is Metal. The image of Qian is perfectly round, shaped like a melon seed, with softness in the center and hardness surrounding it. Therefore, the higher the Heaven, the harder it is; the lower the Earth, the harder it is. Qin Shi Huang built his tomb at Mount Li, digging three hundred zhang deep into the yellow springs; chiseling did not penetrate it, burning did not destroy it. Unless it were the utmost Hard Qi and the true body of Metal, how could it be so robust and operate endlessly? Therefore, all Qi-transformed things, lacking Metal Qi, cannot be strong. Thus, the shells on the outside serving as protection all obtain Qian Metal Qi to solidify their form. Thus, among the myriad things of Wu Xing, nothing is possible without Metal.
From this observation, the principles of Wu Xing interact infinitely. Therefore, Jia, Bing, Wu, Geng, Ren are the Yang Stems of Heaven, interacting with Zi, Yin, Chen, Wu, Shen, Xu of Earth; Yi, Ding, Ji, Xin, Gui are the Yin Stems of Heaven, interacting with Chou, Hai, You, Wei, Si, Mao of Earth. Heaven and Earth Wu Xing interlock and combine; the ten Stems of Heaven interact with the twelve Branches of Earth. Thus, within Wu Xing, each possesses Wu Xing, forming the Sixty Jiazi cycle. Extending from the Sixty Jiazi to Heaven, Earth, and all things, how can the changes be fully spoken of? However, although changes are infinite, they never go beyond Yin and Yang; the function of Yin and Yang never goes beyond Water and Fire. Therefore, nowhere in Heaven and Earth is there not the function of Water and Fire. To summarize the principle of Wu Xing in one sentence: Qian and Kun endow Kan and Li with their true nature; Kan and Li are the functions of Qian and Kun.