My favorite solar term is the solstice in winter, because

The so-called winter solstice day, according to the explanation in ancient books, has three meanings: one is cathode, the other is sun, and the third is south, hence the name. In the long-term practice, people found that from the day of winter solstice, the days became longer and longer, the sun moved to the southernmost point and began to return to the north (Tropic of Capricorn).

The ancients used the concept of yin and yang to explain this climate change. They thought that from this time on, yin began to fall and yang gradually rose, so the winter solstice became the node of yin and yang transformation.

In an agricultural society that depends on the weather, longer illumination time is undoubtedly more conducive to the growth of crops. Therefore, the day when the day begins to get longer is undoubtedly of great significance.

At the same time, in the concept of the ancients, the sunshine becomes longer, which is the process in which the Yang between heaven and earth tries to "overcome" the Yin. Then, as a stranger looking forward to the victory of the sun be the spirit, they will naturally find ways to "cheer up" the sun be the spirit. Many rituals and customs of winter solstice sacrifice that we see in ancient books actually have this meaning.

So, how to determine which day is the winter solstice? Probably from the pre-Qin period, our clever ancestors found some signs of the arrival of the winter solstice from the changes of everything in the world. For example, in "Summer Zheng Xiao", it is recorded that "there is a falling angle, a falling, winter solstice, the sun is smart, and all directions are foggy." People will also measure the date of winter solstice by measuring the shadows of the sun and the moon. For example, there is a saying in Shangshu Yaodian that "the day is short and the stars are high, and it is mid-winter". This method of measuring the shadow of the sundial lasted for many dynasties in later generations.

In ancient times, when the concept of Yin-Yang and Five Elements prevailed, the new dynasty changed clothes after its establishment. In addition to calendar time and other functional considerations, it is a process of building political legitimacy. However, the folklore of 18 years old does not necessarily change with this activity.

The weekly calendar has been implemented for more than 800 years, and the corresponding rural slang has long been formed among the people. For a long time, people have become accustomed to celebrating the winter solstice as the New Year. Moreover, in ancient agricultural practice, it is undoubtedly more in line with agricultural practice to take the winter solstice, which marks the moving node of the sun, as the beginning of the new year. After all, the sun will come back after winter on the solstice. This is why later generations have the saying that winter solstice is as big as a year. After all, for a long time, the solstice was originally the winter of the year!