Introduction: Why Pause at the Point of Equilibrium$1

Between Heaven and Earth, all things have their proper measure. When we speak of the "Spring Equinox" (chunfen) today, we tend to treat it as nothing more than an ordinary mark on the calendar -- a certain date when day and night are equal in length and spring is half over. Yet such an understanding does a grave injustice to the millennia of careful observation our ancestors devoted to the heavens above and the earth below. The Spring Equinox is by no means a simple temporal marker; it is the crystallization of the ancients' profound recognition of "balance" as a fundamental law of the cosmos -- a solemn moment when the Way of Heaven reveals its character of "centrality and rectitude" to the human world within the cycle of the year.

Why should we re-examine the Spring Equinox from the perspective of high antiquity and the pre-Qin era$2 Because that was the age in which this solar term was born -- an age when its meaning had not yet been obscured by layer upon layer of later commentaries, nor reduced by the precise figures of modern calendrics. In that age, fen ("division") was not an astronomical term but a cosmic experience; the equality of day and night was not a set of data to be looked up in a table, but proof that Heaven and Earth were displaying their virtue of "impartiality" to humankind.

The Book of Documents (Shangshu), in its "Canon of Yao" (Yao dian), states: "He thereupon commanded Xi and He, reverently to accord with the august heavens, to calculate and delineate the movements of the sun, moon, and stars, and respectfully to bestow the seasons upon the people." These few words capture the fundamental purpose behind the birth of the solar terms -- "respectfully bestowing the seasons." The single character jing ("reverently") and the single character shou ("bestow") elevate astronomical observation to a near-religious height. And in the passage that immediately follows in the "Canon of Yao," the duties assigned to Xizhong, who was dispatched to the east, are directly related to the Spring Equinox: "He separately commanded Xizhong to reside at Yuyi, called Yangu (Valley of the Sunrise). There he was reverently to receive the rising sun and arrange in order the labors of spring. When the day is of medium length, and the star Niao (Bird) culminates at dusk, thereby one may determine mid-spring." The phrase "day of medium length" (rizhong) refers precisely to the Spring Equinox -- the day when day and night are equally divided. The character ping ("level, equal") and the character yin (meaning "to fix, to determine") reveal the ancients' core understanding of the equinox: this is a node for "calibration," a moment when Heaven and Earth calibrate their own balance.

This touches upon a profoundly deep question: why did the ancients set such store by "equal division"$3 Why, in the course of a year, did they specifically mark out those two days when day and night are equal (the Spring and Autumn Equinoxes) and confer upon them such exalted status$4 Of the more than three hundred and sixty days in a year, the vast majority have unequal day and night -- either the days are longer or the nights are. Only on the Spring and Autumn Equinoxes are day and night precisely equal. Why were the ancients so fascinated by this state of "equality"$5

The answer touches the very core of Chinese thought. In the view of the ancients, jun ("evenness"), ping ("balance"), zhong ("centrality"), and he ("harmony") were not mediocrity, nor the compromise of a middle road, but a supreme virtue -- an ideal state toward which the operations of the cosmos strive. Master Dong Zhongshu gave the most precise definition of the Spring Equinox in his Luxuriant Dew of the Spring and Autumn Annals (Chunqiu fanlu): "The Spring Equinox is when yin and yang are in equal halves; therefore day and night are equal and cold and heat are balanced." This statement may appear merely to describe an astronomical fact, yet it contains an entire philosophical celebration of "balance."

The "Commentary on the Judgment" (Tuan zhuan) of the Qian (Heaven) hexagram in the Book of Changes (Yijing) states: "The Way of Qian transforms and changes, each thing receiving its correct nature and destiny, preserving and uniting the Great Harmony -- thus it is fitting and upright." The so-called "Great Harmony" (taihe) is the highest harmony; and "preserving and uniting the Great Harmony" means that amid the ceaseless transformation of all things, that fundamental balance is always maintained. The Spring Equinox is precisely the most intuitive, most concrete manifestation of this "Great Harmony" in the sequence of the year -- yin and yang in equal halves, impartial and unbiased, all things receiving their correct nature and destiny in this absolute equilibrium, flourishing in vigorous growth.

This article will set out from the core ideas of both the Confucian and Daoist traditions of the pre-Qin era, tracing back to still more ancient mythological and ritual traditions, to offer as thorough an interpretation as possible of the "Spring Equinox" solar term. We wish not only to know what the Spring Equinox is, but to ask why it is so; not only to understand what the ancients did at the Spring Equinox, but to comprehend why they did it. Above all, we wish to ask: what profound cosmology and wisdom for living lie hidden in the seemingly unremarkable point of "equal division"$6 Why did "centrality" and "harmony" become the most cherished values of Chinese civilization$7 In the course of this inquiry, perhaps we can once more touch that ancient world in which all things were alive with spirit, Heaven and humanity were in mutual resonance, and "balance" was held to be beautiful.