Ancient wisdom divided the year into 24 Solar Terms and they still remain relevant today, Yang Yang reports.

The Start of Spring as depicted during the Beijing 2022 Winter Olympics' opening ceremony on Feb 4. (FENG YONGBIN / CHINA DAILY)

The opening ceremony of the Beijing 2022 Winter Olympics on Feb 4 presented a visual feast, displaying Chinese people's understanding of the Games and the relationship between humans and nature. On taking a closer look, one may find many ingenious designs－the countdown included.

On the Chinese traditional calendar, Feb 4, 2022 happened to be the Start of Spring, the first of the Twenty-four Solar Terms. Director Zhang Yimou used them to "greet the arrival of spring". The countdown to the ceremony started from Rain Water, the second solar term (which falls on Saturday) and ended with the Start of Spring. After a desolate winter, the world comes back to life and enters another life circle.

Drawing its curtain on the day of the Start of Spring, the Games auspiciously foretold a vibrant spring for not only athletes but the entire human race.

The solar terms, having been developed throughout Chinese history since about 3,000 years ago and listed on the UNESCO's Representative List of the Intangible Cultural Heritage of Humanity in 2016, are so important to Chinese people that it appears both creative and natural for Zhang to employ and showcase them as a unique part of Chinese civilization to the world.

Hailed as China's fifth greatest invention, in addition to papermaking, the compass, gunpowder and printing techniques, the solar terms were created and developed based on ancient Chinese people's observations of celestial bodies and nature.

The ancient Chinese divided the Earth's elliptical orbit around the sun into 24 segments. Each segment was called a specific solar term. These Twenty-four Solar Terms originated in Central China and have been progressively applied nationally.

Chinese people observing the solar terms, such as tending crops on Rain Water. (MENG ZHONGDE / FOR CHINA DAILY)

Conforming to the movement of the Earth and changes in nature, a year is divided into 24 periods, each of 15 days. Following the Start of Spring and Rain Water are Awakening of Insects, Spring Equinox, Pure Brightness, Grain Rain, Start of Summer, Grain Buds, Grain in Ears, Summer Solstice, Minor Heat, Major Heat, Start of Autumn, End of Heat, White Dew, Autumn Equinox, Cold Dew, Frost's Descent, Start of Winter, Minor Snow, Major Snow, Winter Solstice, Minor Cold and Major Cold.

According to phenological observations, the Chinese in ancient times further divided each 15 days evenly into three sections and marked each section with a natural phenomenon. For example, in the first five days from the day of Start of Spring, warm east winds start thawing the frozen land; in the second five days, hibernating insects awaken in their caves; and in the third, river ice starts melting and fish swim among the floating ice fragments.

In the first five days of Rain Water, otters start catching fish. Five days later, wild geese start flying north from their winter sojourn in the warm south. In the last five days of this period, as the name indicates, rain falls and grass grows and trees start budding.

Li Xiutang, a 68-year-old retired senior middle school teacher in Suqian, East China's Jiangsu province, still remembers the proverbs he learned from his grandfather decades ago. Located on the lower stream of the Huaihe River, having four distinct seasons, Suqian is a place where the solar terms can accurately reflect the changes of weather throughout the year.

"In times gone by, at the regular fairs in different towns, there were people who 'sang the calendar'," he says.

The "calendar singers" would recite the proverbs and explain the dates to the illiterate farmers: When the Start of Spring or Rain Water comes, and what farmers should do in the fields or to prepare for the changing weather.

"Reading and explaining this calendar was a family tradition passed on down the generations," he says.

Chinese people observing the solar terms, such as making "spring fish", a snack eaten on the Start of Spring. (JI ZHE / FOR CHINA DAILY)

Li's grandfather ran a small workshop making spirit money. At night, there was no electricity or any organized entertainment, so villagers came to Li's home while the grandfather was packing spirit money with a dim kerosene lamp on. "Villagers shared ghost stories and information, including what the calendar singers sang at the fairs," he recalls.

On hot summer nights, when it was sweltering indoors, villagers, young and old, men and women, sat against haystacks in the open air, exchanging stories, gossip and information.

"That's how I learned the solar terms and the farmers' proverbs," Li says.

He easily and succinctly recites these proverbs: "Nurture silkworms on Grain Rain, which will bring you money on Grain Buds"; "Around Pure Brightness, sow melons and beans"; and "It's too early to grow wheat on Autumn Equinox, too late on Frost's Descent, but it's time on Cold Dew".

He continues to talk about the practices prevalent once in the countryside: Traders offered higher prices for fur processed after Frost's Descent because hair fell out if processed earlier; it was better to pickle meat after Winter Solstice; and radish pulled up after Frost's Descent was not bitter.

At the end of the 1970s, Li, a senior middle school graduate, became an agro-technician, promoting agricultural knowledge in villages and treating plant diseases and pests. Proverbs were still helpful, but farmers gradually turned to science and technology to prepare for changing weather.

Chinese people observing the solar terms, such as playing sports on Rain Water. (YANG LEI / XINHUA)

However, for Chinese people, the solar terms go far beyond daily practices that have evolved into customs, especially for festivals. For example, on Tomb Sweeping Day, or Pure Brightness, it is a tradition for Chinese people to visit and clean family grave sites to commemorate their ancestors.

Since each solar term reminds people of different views, practices and feelings, they naturally have become the subjects of writers and poets, engraved deeply in the Chinese cultural gene.

For example, Du Fu, a great poet from the Tang Dynasty (618-907), wrote in a poem Yueye Yi Shedi (Missing My Brothers on a Moonlit Night): "Rolls of war drums break people's journey, a wild goose honks above this remote place. Dew turns white since tonight, the moon viewed at home is more bright". He wrote the poem on the White Dew, when wild geese start flying from the north to the warmer south for the coming winter.

When ancient Chinese people saw a different view, they would know it was a certain time of the year. A falling leaf heralded autumn, a cricket at one's house suggested it was Minor Heat, and tigers usually mated during the last five days of Major Snow.

"Chinese calendric culture reflects ancient people's love for life and the world," said writer Wang Meng, in a conversation with Xu Lijing that was collected in Xu's book Ershisi Jieqi Qishi'er Hou (Twenty-four Solar Terms and Seventy-two Phenological Signals), published in January.

Yu Shicun writes in the prescript of his book Shijian Zhishu (Book of Time) that the solar terms display Chinese people's wisdom and are an empirical demonstration of the relationship of "being and time". Chinese people use the solar terms not only to instruct life and work, but also to reflect on their moral courage or behavior.

In nature, a bird perches on a flower on the Start of Spring. (TAN KAIXING / FOR CHINA DAILY)

However, as time passes and people have relied more on science and technology, the solar terms seem less useful than they were in ancient times. Living a fast-paced life in modern cities of steel, cement and glass, people, working around the clock, have lost their sense of time and connection with nature. Depression and insomnia are blighting an increasing number of people's lives.

"Now many people live their life, not according to the instruction of the Twenty-four Solar Terms, but deadlines," says Li Min, astronomer and a former professor of Nanjing University.

"The decrease of sunlight is related to depression in winter," he says.

Living organisms are also influenced by gravity relationships between the sun, the Earth and the moon, he says, including when to rest and when to work.

"As we see, when people refer to deadlines to adjust their daily schedules, rather than the natural rules developed during the evolution of human beings over tens of thousands of years, many fall ill and some even die suddenly due to overwork," he says.

Scientists have been trying to decipher the riddle of the circadian rhythm of living organisms. In 2017, the Nobel Prize in medicine was awarded to three scientists for their discoveries of molecular mechanisms controlling the circadian rhythm, which explain how plants, animals and humans adapt their biological rhythm to synchronize it with the Earth's revolutions.

"Although the solar terms are a heritage left by ancient agricultural society, it is still meaningful to modern society," Yu was quoted as saying in a previous interview.

Contact the writer at yangyangs@chinadaily.com.cn