Chou

Chou is the second of the twelve Earthly Branches (dizhi). Its zodiac animal is the Ox, its element is Earth, its direction is north-northeast, and its double-hour runs from 1 to 3 am, the deep hours before dawn. As one of the twelve branches it combines with the ten Heavenly Stems to build the sexagenary cycle of sixty used to number years, months, days, and double-hours in the traditional calendar. The branch names the second animal of the twelve-year cycle and the corresponding month and double-hour, carrying the Ox's steady associations in the almanac. These are the conventions of the Chinese calendrical and cosmological tradition, in which the twelve branches order the animal years, the months, and the twelve two-hour periods into which the day is divided.

Chou is the second Earthly Branch, corresponding to the Ox in the twelve-animal cycle, and to the double hour from 1 am to 3 am. Its dominant hidden stem is Ji, giving it the Earth phase, though the theory of hidden stems also assigns it minor Water and Metal influences, a complexity traditional practitioners read as giving Ox-branch charts unusual internal tension between steadiness and hidden reserves. Chou is a Yin-polarity branch, so within the sixty-term sexagenary cycle it only ever pairs with the even-numbered Heavenly Stems, Yi, Ding, Ji, Xin or Gui. In the traditional Chinese calendar's fixed month associations, Chou corresponds to the twelfth lunar month, the last of the year, and in BaZi astrology a chart with Chou prominent is read through the Ox's associations of patience, diligence and a capacity to bear sustained burden, alongside a stubbornness the tradition treats as the same trait's cost.

Beyond the animal it carries, a branch enters three fixed sets of relations that the almanac and the fate-calculation tradition use constantly. Chou belongs to the trio Si, You and Chou, one of the four groups of three branches spaced four apart which are read as combining into Metal. It clashes with Wei, the branch six places away, and it forms one of the six harmonies with Zi. These relations are properties of position in the twelve, not of the animal.

The branches also do more work than the year cycle they are best known for. They divide the day into twelve double hours, so Chou names a period of two hours as well as a year and a month; they mark the twelve directions of the compass, Chou standing at north-northeast; and they carry the twelve stations against which the movement of Jupiter was tracked, which is one proposed origin for the twelve-year cycle itself.

The stem-and-branch day count is the longest continuously running day count known. Numbering days by ganzhi begins in the Shang inscriptions and has run without acknowledged interruption since, through every dynastic change and every calendar reform, because the cycle of sixty is independent of any astronomical quantity and therefore needs no correction. Chinese historical dates from the classical period onward can be checked against it.

Chou is one of the four Earth branches, which stand at the close of each season in the month assignment and are read as the transitions between phases rather than as the seasons themselves. That gives the Earth branches a particular character in fate calculation, where they are often described as storehouses, holding the residue of the season that is ending.

Sources Chinese Mathematical Astrology: Reaching Out to the StarsHo Peng Yoke with The Chinese Sexagenary Cycle and the Ritual Origins of the CalendarAdam Smith