The Great Treatise, Chapter Three: The 'Tao' speaks of the images.

義曰：神者，陰陽不測，幽微不可以測度，故曰神；無方者，不見所處，運動不息，是無方也。易者，即周易也；無體者，唯變所適，徃來不窮，是無體也。夫天地之道妙用無門，鬼神之道寂然無跡，春生夏長，藏徃知來，故不可以方隅而論之。夫大易之道總括天地，包含萬象，惟變所適，道無常用，既不可以象類索，又不可以形器求，是亦不可以定體而論之也。是大易之道與天地之道相凖，如鬼神之妙用也。

Hu Yuan explained that "the divine" refers to the changes of yin and yang that are difficult to predict and subtle beyond measurement, hence called divine; "without fixed direction" means that it cannot be seen to stop in a fixed place, and it moves ceaselessly, thus having no fixed location. "Easy" refers to the Zhou Changes (I Ching); "without fixed form" means it follows changes and moves endlessly without end, thus having no fixed form. The way of heaven and earth is profound and boundless with infinite applications, yet has no fixed path to follow. The way of ghosts and spirits is silent and still, leaving no trace. In spring it promotes growth, in summer it fosters development, it stores away the past and foresees the future, so it cannot be confined to a particular direction or corner. The way of the Zhou Changes encompasses heaven and earth, includes all phenomena, follows changes and adapts accordingly, and has no fixed method. It cannot be sought through a particular kind of symbolic image, nor can it be grasped by tangible objects, nor can it be discussed through fixed forms. Thus, the way of the Zhou Changes corresponds exactly to the way of heaven and earth, just as the way of ghosts and spirits is subtle and without fixed direction.

一陰一陽之謂道。

The classic text says: Yin and Yang alternate and shift, using each other, and this is called the Dao.

義曰：道者，自然之謂也。以數言之則謂之一，以體言之則謂之無，以開物通務言之則謂之通，以微妙不測言之則謂之神，以應機變化則謂之易，總五常言之則謂之道也。

Hu Yuan explained that what is called "the Way" is something that is inherently so, without any artificial arrangement. In terms of number, it is called "one"; in terms of essence, it is called "nothingness"; in terms of its ability to open up all things and connect all affairs, it is called "communication"; in terms of its subtle and indescribable nature, it is called "spirit"; and in terms of its adaptability, it is called "ease." When the five constants of benevolence, righteousness, propriety, wisdom, and faithfulness are combined, it is called "the Way."

上既言天地之神、大易之道窮變盡神，妙用無方，不可以方隅形體而求之，此又言天地生成之道。夫獨陽不能自生，獨陰不能自成，是必陰陽相須，然後可以生成萬物。故於冬至之日，陽氣下施，散而為春夏，以生成萬物，以至洪者纎者、髙者下者皆遂其生，以盈滿於天地之間。然萬物既生，不可不成之，故於夏至之日，陰氣下施，散而為秋冬，以成就萬物，以至洪者纎者、髙者下者皆遂其性，以成就於天地之間。是一陰一陽互相推蕩，天覆而地載，日照而月臨，所以謂之道也。

The previous passage has already explained the mysterious nature of heaven and earth, and the principle of the Zhou Changes (I Ching) which exhausts all transformations and divine mechanisms, with its subtle applications not confined to specific directions or forms, and cannot be sought through position or shape. Now we will explain the principle by which heaven and earth generate and nurture things. Alone, yang cannot generate itself, and alone, yin cannot complete itself. It is only when yin and yang rely upon each other that they can generate and nurture all things. Therefore, on the day of Winter Solstice, yang energy begins to descend and spread out, dispersing to become spring and summer, thus generating and nurturing all things, so that large and small, high and low, each can fulfill their nature and fill the space between heaven and earth. However, once things have been generated, they cannot avoid maturing, so on the day of Summer Solstice, yin energy begins to descend and spread out, dispersing to become autumn and winter, thus completing all things, so that large and small, high and low, each can fulfill their nature and complete themselves in the space between heaven and earth. Thus, yin and yang alternately shift and interact, with heaven covering and earth supporting, the sun shining and the moon illuminating, which is called the Dao.

繼之者善也。

The classic text says: Those who can carry forward the principle of yin and yang are considered virtuous.

義曰：夫天地之道、陰陽之功生成萬物，千變萬化以盈滿於天地之間，使高者得其髙之分，卑者得其卑之理。聖人得天地之全性，繼天地生成之功，以仁愛天下之物，以義宜天下之眾，使居上者不陵於下，在下者不過其分，是聖人繼天養物之功以為善行也。故乾卦曰元者善之長，是言天以一元之氣為眾善之長，聖人繼其元善之功以理於物也。

Hu Yuan explained that the way of heaven and earth, the function of yin and yang, generate and nourish all things. There are myriad changes and transformations that fill the space between heaven and earth, enabling those in high positions to occupy their proper places and those in low positions to abide by their appropriate roles. The sage inherits the complete nature of heaven and earth, and continues the function of heaven and earth in generating and nurturing all things: using benevolence to care for all things under heaven, and using righteousness to regulate all people. This ensures that those in superior positions do not oppress those below, and those in inferior positions do not exceed their proper roles. This is the virtuous conduct of the sage, who inherits the function of heaven in nurturing all things. Therefore, the "Wenyan" section of the "Qian" hexagram says "Yuan" is the beginning of all virtues. This means that heaven uses the primordial qi as the starting point of all goodness. The sage inherits the function of this primordial goodness and uses it to govern all things.

成之者性也。

The classic text says: Those who can actualize the principle of yin and yang within themselves are called nature.

義曰：性者，天所稟之性也。天地之性寂然不動，不知所以然而然者，天地之性也。然而元善之氣受之於人，皆有善性，至明而不昏，至正而不邪，至公而不私。聖人得天地之全性，純而不雜，剛而不暴，喜則與天下共喜，怒則與天下共怒，以仁愛天下之人，以義宜天下之物，繼天下之善性以成就己之性。既成就己之性，又成就萬物之性；既成就萬物之性，則於天地之性可參矣。是能繼天地之善者，人之性也。

Hu Yuan explained that what is called "nature" is the inherent nature bestowed by Heaven. The nature of Heaven and Earth is still and unmoving, inexpressible as to why it is so yet naturally so; this is the nature of Heaven and Earth. Once the original benevolent qi is received by humans, each person then possesses a benevolent nature: extremely clear and not obscured, extremely upright and not perverse, extremely just and not biased. The sage receives the complete nature of Heaven and Earth, pure and unimpeded, strong and not fierce, joyful in harmony with the joy of all under heaven, angry in harmony with the anger of all under heaven; using benevolence to love all people, using righteousness to order all things, inheriting the shared benevolent nature of all under heaven to perfect his own nature. Having perfected his own nature, he also perfects the nature of all things; having perfected the nature of all things, he can be ranked with Heaven and Earth as the third. Therefore, it is said that the one who can inherit the benevolence of Heaven and Earth is precisely human nature.

仁者見之謂之仁，知者見之謂之知。

The text says: The benevolent person sees this way and calls it benevolence; the wise person sees this way and calls it wisdom.

義曰：夫聖人得天性之全，故五常之道無所不備；賢人得天性之偏，故五常之道多所不備，或厚於仁而薄於義，或厚於禮而薄於信，是五常之性故不能如聖人之兼也。

Hu Yuan explained that the sage possesses the complete nature of Heaven, thus the five constant virtues of benevolence, righteousness, propriety, wisdom, and faithfulness are all fully present; the virtuous person only possesses one aspect of the heavenly nature, so the five constant virtues are often lacking: some are benevolent but lack righteousness, some emphasize propriety but lack faithfulness. It is precisely because the nature of the five constants is inclined towards one aspect that they cannot be fully possessed as the sage does.

夫大易之道，卦於伏羲，重於文王，爻辭於周公，是三聖人垂萬世法則之書，其間寫天地水火風雷山澤之象，本凖擬於天地，統鬼神之妙用，惟變所適，量時制宜，故不可一義而求之也。若仁者見之則知聖人之仁，知者見之則知聖人之知，是各資其分而已矣。

The Zhou Changes (I Ching) is a book of principles left by three sages: Fuxi created the hexagrams, King Wen arranged them into sixty-four hexagrams, and the Duke of Zhou composed the line statements. The book depicts the images of heaven and earth, water and fire, wind and thunder, and mountains and marshes. These images were originally created by comparing with heaven and earth, encompassing the subtle workings of spirits and deities. They change according to circumstances, balancing situations and adapting to events. Therefore, they cannot be interpreted with a single meaning. A kind-hearted person reads it and sees the benevolence of the sages; a wise person reads it and sees the wisdom of the sages. This is merely each person interpreting it according to their own nature and disposition.

百姓日用而不知，故君子之道鮮矣。

The classic text says: The common people use this Dao every day without realizing they are using it, so those who truly understand the Dao of the gentleman are very few.

義曰：夫聖人得天地之正性，繼天地之行事，故無所不知，無所不明。賢人得天地之偏，又可以仰及於聖人之行事，然聖人之道至深至奧，賢人尚可以偏窺之；至於天下百姓常常之人，得天性之少者，故不可以明聖人所行之事。

Hu Yuan explained that the sages inherited the pure nature of heaven and earth, and carried on their actions, so they knew everything and understood everything clearly. The virtuous men only inherited one aspect of the nature of heaven and earth, yet they could still look up to and approach the deeds of the sages; the way of the sages was extremely profound and subtle, and the virtuous men could only glimpse it from one side. As for the common people of the world, they inherited even less of the heavenly nature, so they could not understand the deeds of the sages: they daily benefited from this doctrine, yet could not explain the reasons behind it.

夫大易之道載聖人之行事，包乾坤之生育、鬼神之妙用、人道之終始，無不備於其間。聖人體其用，成其功業，發見於天下，則天下之人咸戴而行之，莫知所以然而然也。然而聖人君子雖能體易道以為用，觀易道以施化，然能悟君子之道者亦鮮矣。

The Zhou Changes record the conduct of the sage, encompassing the generative functions of Heaven and Earth, the subtle workings of ghosts and spirits, and the beginning and end of human affairs. Nothing is lacking within it. The sage observes its principles, accomplishes his achievements, and manifests them to the world, so that all people honor and follow them, yet they cannot explain why. However, although the sage and the virtuous person can understand the principles of the Zhou Changes and apply them, and observe them to promote education, those who truly comprehend the way of the virtuous person are still few.

顯諸仁，藏諸用。

The classic text says: display benevolence externally and conceal utility internally.

義曰：上言神之所為，此論易道之大與神功不異也。顯諸仁者，言道之為體，顯見仁功，衣被萬物，是其顯也；藏諸用者，謂潛藏功用，不使物知，是藏諸用也。夫天地之道，乾剛坤柔，日臨月照，春生夏長，秋殺冬藏，使萬物綿綿而不絶者，天地生成之仁也，然不知天地生成之用也。

Hu Yuan explained: The previous passage discussed the mysterious power of the divine, while here we discuss the grandeur of the Way of the Zhou Changes, which is no different from that mysterious power.the so-called "显诸仁" means that the Way, as the fundamental principle, manifests the efficacy of benevolence, covering and nurturing all things, which is its manifest aspect; and "藏诸用" means that it conceals its function, so that all things do not perceive it, which is its hidden aspect. The Way of heaven and earth, with the male principle (Qian) being strong and the female principle (Kun) being gentle, the sun and moon taking turns to illuminate, spring for growth, summer for flourishing, autumn for harvesting, and winter for concealment, enabling the continuous continuation of all things, this is the benevolence of heaven and earth in nurturing life; yet people do not know how heaven and earth actually exert this function.

夫聖人之道，恩涵澤浸，政漸仁煦，薄賦輕役，恤孤軫貧，使百姓安其土而不遷，勸其功而樂事者，聖人生成之仁也，然不知聖人生成之用也。夫大易之道，寂然不見其體，杳然不見其形，以之悅懌生民，功業萬世，施為徳澤，則可以衣被萬物，是顯諸仁也；及夫推究原本，測度云為，不見其跡，是藏諸用也。是大易之與天地鬼神無以異也。

The way of the sage is also like this: benevolence and virtue permeate people's hearts, government orders are gentle and the spirit of benevolence is warm and nurturing. Lightening taxes and reducing forced labor, caring for the orphans and the weak, and showing compassion to the poor, so that people can live in peace in their native land without needing to migrate, and encouraging them to diligently pursue their occupations and take pleasure in their duties. This is the benevolence of the sage in nurturing the people. Yet people still do not know how the sage actually exercises this function. The way of the Zhou Changes is so quiet that its essence cannot be seen, so profound that its form cannot be perceived. It brings joy to the people, accomplishes great achievements for all generations, and spreads its grace to all things. This is how benevolence is revealed. But when people investigate its origin and examine its actions, they cannot find any trace. This is how its function is hidden. Therefore, the Zhou Changes is no different from heaven and earth, spirits, and ghosts.

鼔萬物而不與聖人同憂。

The scripture says: Heaven and Earth move and stir, promoting the growth of all things, yet they do not concern themselves with worrying about all things as a sage would.

義曰：夫天地之道，以時而生，以時而殺，雷霆以鼔動之，風雨以滋潤之，使萬物洪者纎者、髙者下者皆遂其性。或萬物之中有夭折暴亡、凶荒札瘥者，皆任自然之理，不能憂恤之。

Hu Yuan explained that the way of Heaven and Earth follows the seasons to generate and to subdue; using thunder to move all things and using wind and rain to nourish all things, so that all things, whether large or small, high or low, can fulfill their nature. Among all things, if there are cases of premature death, sudden demise, disaster, or epidemic disease, Heaven and Earth simply allow them to follow the natural order, without worrying or comforting them.

夫聖人代天牧民，繼天之善，以仁義之道生成於天下，物之夭折暴亡、凶荒札瘥者，常如己內於溝壑之中。是天地之道但能鼔舞於萬物，而不能憂恤於萬物也；聖人能生成於萬物，又能憂恤於萬民也。惜乎聖人所不得者，天地之權也。故大易之道載天地生成之理，而不能與聖人同憂也。老子曰：天地之道，氣猶槖鑰，以萬物為芻狗者，此也。

The sage acts on behalf of Heaven to govern the people, continuing Heaven's benevolence, and nurtures the world with the principles of benevolence and righteousness. When someone dies young or suffers from calamity, plague, or disaster, he always feels as if he had pushed them into the ditch. This shows that the way of Heaven and Earth can only stimulate the growth of all things, but cannot worry for them. The sage can nurture all things and also worry and comfort the people. Unfortunately, the sage lacks the power of Heaven and Earth. Therefore, the way of the Zhou Yi, although recording the principles of Heaven and Earth nurturing things, cannot possess the concern and anxiety of the sage. The Dao De Jing says: Between Heaven and Earth, that vital energy is like a bellows, constantly stirring. Heaven and Earth regard all things as sacrificial straw dogs, letting them be born and die naturally. This is exactly what it means.

盛徳大業至矣哉。

The virtue of nurturing and generating all things is extremely abundant, and the achievements of the sage are extremely vast, truly reaching the pinnacle! Here, "shengde" refers to the virtue of continuous generation and daily renewal, and "daye" refers to the accomplishments of possessing the world and encompassing all things.

義曰：此已下至「陰陽不測之謂神」為一章，此是十翼之中第五章。今註疏之說皆以謂「顯諸仁，藏諸用」而下至「道義之門」為一章。今觀「顯諸仁，藏諸用，鼔萬物而不與聖人同憂」三句，皆言上文天地不測之事，故自此「盛徳」已下至「陰陽不測之謂神」為一章；自「夫易廣矣大矣」而下至「易簡之善」為一章。

Hu Yuan remarked: From here on down to the sentence "Yin and yang are called divine because they are unpredictable," these should be considered as one chapter. This is the fifth chapter of the "Xiyi" (Commentary on the Changes) from the Ten Wings of the "Yijing." At that time, the commonly circulated annotated editions divided from "Manifesting in benevolence, concealing in function" down to "the gate of Dao and righteousness" as one chapter. However, upon closer examination, the three sentences "Manifesting in benevolence, concealing in function, stirring all things without sharing the anxiety of sages" all discuss the matters of heaven and earth's nurturing and transformation that were mentioned earlier, and their meaning still belongs to the previous chapter. Therefore, from the sentence "Great virtue" down to "Yin and yang being unpredictable is called divine" should be considered as one chapter; then from "The Book of Changes is vast and great" down to "the simplicity and ease of the Book of Changes" should be considered as another chapter.

「盛德大業至矣哉」者：夫天地之道，無所不生，無所不育，以生成之功言之，其徳至廣而其功至大也。聖人法天之用，廣生成之道，萬物由之而通，政教由之而理，而又作工巧以便器用，立商賈以通有無，為之綱罟則以畋以漁，為之耒耜則以耘以耨，天下之人至於昆蟲草木，無不被其賜者，是聖人充盛之徳、廣大之業至極矣哉。然必云「盛徳大業」者，蓋施於行則為徳，行於事則為業也。

The phrase "Sheng De Da Ye Zhi Yi Zai" means: the great virtue and great achievements have reached their ultimate state. The principle of the operation of heaven and earth has no single thing that is not generated by it, nor any that is not nurtured by it. In terms of the accomplishment of creation, its virtue extends widely to all things, and its function reaches everywhere. The sage takes the action of heaven as a model, promotes this principle of generation and cultivation: all things thus find their proper course, and government and education are thus properly managed. He also makes various ingenious tools to facilitate the people's daily use, establishes commerce to enable the exchange of goods; he invents nets and traps, so people can hunt and fish; he makes plows and hoes, so people can till the soil and clear weeds. All people, even insects and grasses and trees, are not without the benefit of this. This is the sage's full virtue and great achievements having reached their ultimate state. As for why it is specifically divided into "Sheng De" (great virtue) and "Da Ye" (great achievements), it is because the same thing, when practiced in personal cultivation, is called "De" (virtue), and when applied to practical deeds, is called "Ye" (achievement).

富有之謂大業。

All things are present and full, which is called "Great Achievement."

義曰：自此已下覆說「大業」「盛徳」，因廣明《易》與乾坤之事。夫天之生物盈滿於天地之間，則謂之富；聖人法天之行事，布其徳澤，施其教化，竭天下之財用，聚天下之民物，以為之富有，富有天下，措當世於不拔，故謂之大業也。

From this sentence onwards, the text goes back to elaborate separately on the previous concepts of "great undertaking" and "abundant virtue," using them to broadly explain the principles of the Zhou Changes (I Ching) and the two trigrams, Qian (Heaven) and Kun (Earth). Heaven generates all things, filling the space between heaven and earth. This omnipresence is called "richness." The sage emulates Heaven in governing affairs: bestowing grace, promoting moral education, mobilizing the wealth and resources of the world, and gathering the people and resources of the world, thus making the state rich. Being rich in the whole world, yet able to establish the present age on an unshakable foundation, is called "great undertaking."

日新之謂盛徳。

Each day becomes more renewed and never ceases, which is called "abundant virtue."

義曰：夫天地之道，日往月來，陰極陽生，四時更變，寒暑相推，一日復一日，其徳愈新，以至生成萬物，日日而盛大。聖人法此天地之道，増修其徳，持循政教，適時之變，量事制宜，使其徳日日盛大。

The principle of the operation of heaven and earth is that the sun sets and the moon rises, when yin energy reaches its extreme, yang energy arises, the four seasons alternate in turn, cold and heat shift alternately, one day follows another, its virtue constantly renews itself, thus generating and completing all things, becoming more and more grand. The sage follows this principle of heaven and earth, constantly cultivating and enhancing his virtue, maintaining and adjusting his decrees and education, adapting to the changes of the times, weighing the importance of matters and establishing appropriate measures, so that his virtue also becomes more and more grand.

生生之謂易。

Things keep coming into being and transforming continuously, which is called "Easy."

義曰：生生者，陰生陽，陽生陰也。天地之道、聖人之徳，以富有言之則謂之大業，以日新言之則謂之盛徳，而又生成之道，變化死生，生而復死，死而復生，使萬物綿綿而不絶者，天地聖人之徳業也。

The concept of "shengsheng" refers to the generation of yin giving rise to yang, and yang in turn giving rise to yin, in a continuous cycle. The principles of heaven and earth, as well as the virtue of sages, are called "daye" from the perspective of being all-encompassing and boundless, and "shengde" from the perspective of daily renewal. Its transformative and productive function is manifested in the changes of life and death—birth followed by death, death followed by birth—ensuring the continuous succession and unending continuation of all things. This is precisely the shared virtue and achievement of heaven and earth as well as sages.

夫大《易》之道，盡七九八六之數，寫天地水火雷風山澤之象，總陰陽生殺之理，包人事萬物之宜，變而必通，終而復始，隨時之變，因事制宜，凖擬天地之間，則其功不異，是生生相續而不絶也。

The principles of the Zhou Changes encompass the numbers obtained through divination with yarrow stalks, namely the minor yang seven, the old yang nine, the minor yin eight, and the old yin six. It depicts the eight natural phenomena: heaven, earth, water, fire, thunder, wind, mountain, and marsh. It summarizes the principles of the growth and decline of yin and yang, and includes the appropriate measures for human affairs and all things. After change, it must become通畅, and after completion, it begins anew, adapting to circumstances and establishing suitable methods according to the situation. By comparing it to the operation of heaven and earth, its effectiveness is no different from that of heaven and earth—this is the continuous cycle of generation and renewal, never ceasing.

成象之謂乾。

It becomes the image of the strong and vigorous things in the world, which is called "Qian."

義曰：乾者，健也。夫天以一元之氣，仰而望之，其色蒼蒼然，下周於地，其狀如倚杵。南樞入地三十六度，北樞出地三十六度，一書一夜凡行九十餘萬里，自古至今未嘗有毫釐之差忒，亦未嘗有分毫之不及，以至生成萬物，皆以乾健而神其用，以成就萬物之形狀。非剛健之功則不能如是也，故伏羲始畫乾卦，皆取健用為象也。

The meaning of "Qian" (乾) is firm and vigorous. Heaven is composed of a single, undifferentiated vital energy, and when looked up at, it appears vast and boundless. It extends downward to encircle the earth, resembling an inclined wooden pestle. The southern celestial pole is thirty-six degrees below the horizon, while the northern celestial pole is thirty-six degrees above it, and in one day and night, it travels over ninety thousand li. From ancient times to the present, its movement has never deviated by the slightest, nor has it ever been delayed in the slightest. Until it transforms and creates all things, it operates mysteriously through this vigorous force, thus forming the shapes and appearances of all things. Without this vigorous function, such a result would be impossible. Therefore, when Fuxi first drew the Qian trigram, he took the aspect of firmness and vigor as the basis for his symbolic representation.

效法之謂坤。

Modeling after Heaven and carrying forth the nurturing and generation of all things, this is called "Kun."

義曰：坤者，順也。夫坤地之道，承天之氣而始終萬物，無所不載，無所不生，皆效天而生育之，故伏羲畫坤之卦，亦皆取效坤順之義而名曰坤。然則必言「成象之謂乾，效法之謂坤」者，蓋萬物之生必由天道剛健，然後成其形象；地道柔順，必得陽氣，然後順其物理。以人事言之，乾則為君之象，坤則言臣之道，天下之事非君不能立，庶政之設非臣不能行也。

"The meaning of 'Kun' is to be gentle and yielding. The way of the earth is to accept the energy from heaven, thus beginning and completing the nurturing of all things. Nothing is not carried by it, and nothing is not generated through it. All things follow the way of heaven to cultivate and transform. Therefore, when Fuxi drew the Kun hexagram, he also took this meaning of following and yielding, naming it 'Kun'. As for why it is specifically said 'the manifest image is called Qian, and the following is called Kun', it is because the generation of all things must first have the vigorous nature of the heavenly way to form the shape and image of things; and the way of the earth, being gentle and yielding, also needs the yang energy to smoothly follow the principles of all things. If we take human affairs as an analogy, Qian represents the sovereign, and Kun represents the subject's duty: great affairs of the world cannot be established without a sovereign; various administrative tasks cannot be carried out without subjects."

極數知來之謂占。

By thoroughly investigating the numbers of the divination tortoise shells to foresee the future, this is called 'divination'.

義曰：夫大《易》之道，總包天地，動賾鬼神，天下之事不言而自知，吉凶之道未萌而先見，皆聖人以蓍象之數占其事物之理，逆知來事之意，考其行事之驗，以成其文也。故下文所謂「將有為也，問焉而以言，其受命也如響」，此之謂也。

The principles of The Zhou Changes encompass the whole of heaven and earth, capable of sensing deep and hidden matters and the workings of ghosts and spirits. All things under heaven become clear without needing to be spoken of, and the trends of good or ill are seen before they even begin to manifest. This is what the sages achieved through the use of the yarrow stalks and the hexagrams, revealing the inner principles of things and foreseeing future developments. They then verified these predictions through actual events, and recorded them as the line statements of the hexagrams. Therefore, the following says, "About to take action, one consults the yarrow stalks and asks with words; it responds as if echoing immediately," referring precisely to this matter.

通變之謂事。

Understanding change and following the trend to act, this is called "affair."

義曰：夫暑徃則寒來，陽生則陰伏，物之所以理，事之所以通，生而後滋，周而復始，皆自於變化之力也。故黃帝通其變，使民不倦，神而化之，使民宜之，《易》窮則變，變則通，通則久，是皆自通變之道，然後成天下之事也。

When the heat of summer passes, the cold of winter comes; when yang energy arises, yin energy retreats. All things are able to follow their proper principles, and affairs can proceed smoothly because they are born and then continue to grow, completing a cycle and then beginning anew. All of this arises from the power of change. Therefore, the "Xiwai" section of the "Zhouyi" says about the Yellow Emperor: "He understands change and thus the people are not weary; he transforms things in a mysterious way, so the people can live in harmony." He understands the changes of things, so the people are not tired; he subtly transforms them in a divine manner, so the people can live in accordance with their proper conditions. It also says that the principle of the "Zhouyi" is that when something reaches its limit, it changes; when it changes, it becomes unobstructed; when it becomes unobstructed, it can endure. All of these are based on first mastering the principle of change and transformation, and only then can one accomplish great deeds in the world.

陰陽不測之謂神。

The subtle and profound effects of the interaction between yin and yang are called "spirit" (shen).

義曰：夫萬物之生，皆由天地陰陽之功以生成之。然生成之道，周而復始，極而復生，不言而信，不疾而行，以至變化之理及究其生育之形，不可得而知也。

All things come into being through the transformative power of heaven and earth, yin and yang. However, this process of transformation completes a cycle and then begins anew, reaching its extreme and then re-emerging. It speaks not a word yet all things naturally obey, it does not rush yet it is present everywhere. Thus, the principles of change and the process by which all things take form remain ultimately unknown to humans. This profound and indescribable nature is called "shen."