Ancient methods of dating the day

The day was the first unit of timekeeping to appear.

The concept of stems and branches: heaven is the stem, earth is the branch. Ten heavenly stems are: A B C D E H G S N K; twelve earthly branches are: Zi ugly Yin Mao Chen Si Wu Wei Shen You Xu Hai. Sixty A Zi: ten stems and twelve branches in order to combine for sixty units, the combination of the method is to the single number of heavenly stems with the single number of Earthly Branches, the double number of heavenly stems with the double number of Earthly Branches, from the beginning of the A Zi, to the end of the Kui Hai, known as the sixty A Zi.

The stem and branch solar calendar method: it arose around the Yin and Shang Dynasties. Since the Spring and Autumn Period and the Warring States Period, the stem-and-branch solar calendar has become the traditional method for historians to keep track of the sun. The world's longest application of the solar calendar: the Spring and Autumn period, Lu Yindong three years in February, the day of the sixth (February 10, 720 BC) from the stem and branch of the solar calendar, until the Qing Dynasty Xuantong three years (1911 AD), counting more than two thousand six hundred years, has never been interrupted. Tiangan Jiyi: As early as the Xia Dynasty may have been produced, that is, the use of A, B, C, D and other ten characters to Jiyi. After gradually not used.

Most of the Yellow Emperor's Classic of Internal Medicine (HUNDI NEIJING) use only the celestial stems for the date of the day, for example, "Suwen - Zangqi Fazhi Lun": "Liver disease, healing in the C-Ding, C-Ding is not healed, added to the Geng-Sin, Geng-Sin does not die, held in the Non-Kai, starting in the A-B." All four sets of heavenly stems in the sentence refer to the day.

Certain days had specific names in ancient times: that is, they were dated according to the monthly moon phases (various different images of the bright part of the moon). Example: Hope does not make up for obscurity, and the strings are not taken away from the moon, and the sigmoid is not used. (Jin Dou Hanqing's "Marking the Specter")