From End to Beginning: The Way of Culmination and Return in the Great Cold Solar Term
This article offers a deep reading of Great Cold (Dahan), the final of the Twenty-Four Solar Terms, drawing on pre-Qin Confucian and Daoist philosophy, etymological analysis, and astronomical and phenological traditions. It reveals the dialectic of extreme cold and returning spring, the cyclic principle that every ending harbors a new beginning, and illuminates the late-winter rites of the Grand Nuo exorcism and the clay ox ceremony—inviting the reader into the ancients' cosmic wisdom of 'tracing origins by returning to endings' and the eternal circle of ceaseless renewal.

Chapter Eight: The World of Phenology (Part One)--Hens Begin to Brood: New Life Gestating Amid Utmost Cold
I. The Three Pentads of Great Cold in the Yizhoushu (Lost Book of Zhou), "Explanations of Seasonal Training"
How did the ancients confirm Great Cold's arrival through natural phenomena$18 The answer lies in "phenology." The Yizhoushu, "Explanations of Seasonal Training" (Shixun Jie), provides detailed phenological descriptions for each solar term. Regarding Great Cold, it records:
"On the day of Great Cold, hens begin to brood. After five more days, raptors hunt with fierce swiftness. After five more days, the ice on lakes and marshes freezes to the core."
These are the famous "Three Pentads of Great Cold": first pentad, "hens begin to brood"; second pentad, "raptors hunt with fierce swiftness"; third pentad, "the ice on lakes and marshes freezes to the core." Each pentad lasts five days, and three pentads make the fifteen-day span of the Great Cold solar term.
The arrangement of these three pentads contains exceedingly profound logic, and at the heart of that logic is Great Cold's essential nature of "yin at its extreme, yang being born" and "extreme cold, returning spring." Let us examine each in depth. This chapter treats the first pentad, "hens begin to brood."
II. "Hens Begin to Brood": Why Do Hens Incubate in the Coldest Time$19
"Hens begin to brood" (ji shi ru)--hens begin to incubate and rear chicks. "Ru" here means "to give birth," "to nurse," "to brood." In the coldest solar term of the year, hens begin to nurture new life--what a deeply suggestive, richly symbolic phenological sign!
Why hens$20 Why do they begin "brooding" at this, the coldest time$21 This is no arbitrary arrangement but the crystallization of the ancients' most subtle observation and most profound comprehension of nature.
First, let us understand the special place of the rooster in the ancients' worldview. The rooster is the "herald of dawn"--it crows at daybreak, calling forth the sun's rising, the messenger at the boundary between darkness and light. The Book of Odes, "Zheng Feng," "The Wife Says the Cock Crows," opens: "The wife says the cock has crowed; the husband says the sky grows light." The cock's crow has since antiquity been the signal that "dawn approaches" and "light is coming." In the ancients' symbolic system, the chicken has a natural connection with "yang-qi," "light," and "new life"--it is the emissary that welcomes the sun and welcomes the light.
Why then does "hens begin to brood" (hens nurturing new life) occur precisely during Great Cold$22 Because the chicken is the domestic fowl most sensitive to "yang-qi"! As we have repeatedly demonstrated: although Great Cold is the coldest, yang-qi (since the Winter Solstice's return of one yang) has long since germinated and grown to the Lin hexagram's "two yang." This yang-qi quietly growing underground is imperceptible to ordinary people, but the dawn-heralding chicken, with its natural sensitivity to yang, is the first to respond! The hen senses the recovery and gradual growth of yang-qi between heaven and earth, and instinctively begins to brood new life--she uses her own body heat to echo the reviving yang-qi, initiating the warmest work of life's nurture at the coldest time.
This is the deep meaning of "hens begin to brood": it is the most vivid, warmest confirmation in the animal world of Great Cold's "yin at its extreme, yang being born." When heaven and earth are locked in ice and snow and all things seem dead in the stillness of Great Cold, the hen responds to that subtle yang-qi and begins her brooding--this is heaven and earth proclaiming through the hen to humankind: "Though it is coldest now, yang-qi has already returned, new life is already being nurtured, spring lies just ahead!" "Hens begin to brood" is Great Cold's first, and warmest, signal of hope.
III. New Life Gestating in Utmost Cold: Philosophy in Phenology
"Hens begin to brood" as Great Cold's first pentad carries philosophical implications deep enough to reward repeated reflection. It reveals a fundamental proposition running through Eastern wisdom: new life gestates precisely in the utmost cold; vitality hides precisely in deathly stillness.
In the common imagination, the nurturing of life should happen in the warmth of spring. Yet the ancients' observation tells us: the nurturing of life actually begins quietly in the coldest Great Cold. The hen does not wait for warm spring blossoms to brood, but in Great Cold--when yang-qi has just begun its return and bitter cold has yet to recede--she already responds to yang-qi and initiates new life. This means: the root of spring's "birth" lies not in spring itself, but in the deepest cold of winter!
This accords perfectly with everything we have expounded: "when things end, they begin again," "extreme cold, returning spring," "returning to root, returning to destiny." New life does not appear from nowhere in spring; it is nurtured, initiated in Great Cold's utmost yin and cold, borrowing the quietly returning yang-qi. By the time of Start of Spring or Spring Equinox, what happens is merely the hatching and emergence of new life into the world; its true "inception of nurture" lies in Great Cold.
This insight is immensely encouraging. It tells us: the coldest, most difficult, most seemingly dead moment may be precisely when new life, new hope is quietly being nurtured. Do not despair because you find yourself in a Great-Cold-like winter, for in this very winter's depths, "hens begin to brood"--new life is being nurtured. The deeper wisdom behind "if winter comes, can spring be far behind" is this: spring's seed is planted and incubated at the coldest moment of winter. In the utmost cold, new life stirs.
IV. The Chicken and the "Five Virtues": The Chicken in the Confucian Vision
The chicken holds an exalted place in Chinese culture; the ancients even attributed "Five Virtues" to it. The Hanshi Waizhuan records Tian Rao's discourse on the chicken's virtues: "Have you not seen the chicken$23 Its comb upon its head--that is culture (wen). Its spurs upon its feet--that is martial prowess (wu). Facing an enemy and daring to fight--that is courage (yong). Finding food and calling its companions--that is benevolence (ren). Keeping watch through the night without missing the hour--that is trustworthiness (xin). The chicken possesses these five virtues."
Culture, martial prowess, courage, benevolence, trustworthiness--these are precisely the virtues Confucianism esteems. That Great Cold's first pentad employs this creature embodying the "Five Virtues" to "begin brooding" (nurture new life) is perhaps not the ancients' deliberate design, yet the symbolism is deeply suggestive. The new life nurtured during Great Cold is nurtured by a mother possessing "culture, martial prowess, courage, benevolence, and trustworthiness"--intimating that the new year, the new life, should come bearing these fine virtues. Especially the chicken's "trustworthiness"--"keeping watch without missing the hour," heralding dawn punctually, never defaulting--echoes the "trustworthiness" of the Way of Heaven that Great Cold represents: cold comes and heat goes, endings give rise to beginnings, the Way of Heaven never defaults; when it is time to be cold, it is cold; when it is time to warm again, it warms; when it is time to nurture new life (Great Cold), "hens begin to brood." The chicken's "keeping watch without missing the hour" makes it the perfect symbol of the Way of Heaven's cyclical trustworthiness.
The Way of Heaven is trustworthy, and therefore although Great Cold is bitterly cold, spring must return; the chicken is trustworthy, and therefore although the night-watch is darkest, dawn must be heralded. That hens begin to brood at Great Cold is the unity of "the Way of Heaven's trustworthiness" and "the chicken's virtue of trustworthiness"--it solemnly assures humankind: the cycle is unfailing, new life must come, spring must arrive.