The ancients divided a day and night into twelve periods, and each period was called an hour. Twelve o'clock can refer to either a day or any time. Twelve o'clock was summed up by the ancients according to the appearance and appearance of the sun, the change of the sky, their daily production activities and living habits.
Twelve hours?
Zi, Ugly, Yin, Mao, Chen, Wu, Shen, You. People can trace the origin of these words from ancient books in the pre-Qin period.
Before the Han Dynasty, these appellations were different. It was not until the early years of the Han Dynasty that taichu calendar Law was implemented in China. "Twelve o'clock a day, the main branch is the subject." (Zhao Yi's Examination of Jade Cong, Volume 34) Basic stereotypes and naming. Twelve o'clock is unique and has a long history. It is an outstanding contribution of the Chinese nation to the astronomical calendar of mankind, and it is also one of the cultural treasures of China.