Time is expressed as 24 hours every day and night, which was 12 hours in ancient times. When western mechanical clocks and watches were introduced into China, people called the Chinese and western time points "Da Shi" and "Shi Shi" respectively.
Heavenly stems and earthly branches, the main branch for short, originated from the observation of astronomical phenomena in ancient China. "A, B, C, D, E, Ji, G, Xin, Ren and Gui" are called ten heavenly stems, and "Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai" are called twelve earthly branches.
Heavenly stems and earthly branches constitutes the ancient calendar. Ten branches and twelve branches are matched in turn to form sixty basic units, which cooperate with each other in a fixed order to form the epoch method of branches and branches. The invention of trunks and branches marked the emergence of the most primitive calendar, which was used to calculate the age by numbers.
Extended data
1, main branch year
The chronology of trunk and branch consists of 60 chronologies of trunk and branch in heavenly stems and earthly branches, with a period of 60 years.
The chronology of the dry branch sprouted in the Western Han Dynasty, began with Wang Mang, and prevailed in the late Eastern Han Dynasty. In the second year of Emperor Yuanhe of the Han and Yuan Dynasties (85 years), the court ordered the implementation of the chronicle of cadres throughout the country.
The first year of the calendar year is "Jiazi" (for example, the slogan of the Yellow Scarf Uprising is "Jiazi, the world is prosperous"), and the second year is "Ugliness", and so on, with a cycle of 60 years; After a cycle, it will be reused again and again. (60 is the least common multiple of 10 and 12, so every 60 years is a period).
For example, 1644 is probably the year of Shen Jia, 60 years later, 1704 is also the year of Shen Jia, and 300 years later, 1944 is still the year of Shen Jia. Note that the above is only approximate correspondence, because Gregorian calendar and trunk calendar are different calendars, and the starting point of a year is different.
2. Dry branches and the moon
Yue Ji, the main branch, developed from the twelfth lunar month. According to the five elements of righteousness, make a scene "take the five elements of love and build it by fighting the machine." Party A and Party B call it dry when naming the day, ugly when naming the month, and branch. There is something in the sky that uses the sky, and there is something in the ground that uses the moon. Yin and Yang are different, so there are branches and branches. " So we can know that at the beginning of the invention, stems and branches were used to record the sun and branches were used to record the moon.
3, the main branch timing
60 hours is a five-day cycle; Reuse after a cycle, cycle after cycle, cycle. It must be noted that time periods are divided into early time periods (early time periods) from 0: 00 to 1 and late time periods (late time periods) from 23: 00 to 24: 00, so when you meet A or yourself, 0: 00 to 1 is a time period, and 23: 00 to 24: 00 is a time period. Late night is also called midnight or night.
References:
Baidu Encyclopedia-heavenly stems and earthly branches