Shen

Shen is the ninth of the twelve Earthly Branches (dizhi). Its zodiac animal is the Monkey, its element is Metal, its direction is west-southwest, and its double-hour runs from 3 to 5 pm, the mid-afternoon. As one of the twelve branches it combines with the ten Heavenly Stems to form the sexagenary cycle of sixty that numbers years, months, days, and double-hours. The branch names the ninth animal of the twelve-year cycle and the corresponding month and double-hour, carrying the Monkey's quick and clever 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 twelve months, and the twelve two-hour periods into which the day is divided from midnight to midnight.

Shen is the ninth Earthly Branch, corresponding to the Monkey, and to the double hour from 3 pm to 5 pm. Its dominant hidden stem is Geng, giving it the Metal phase, with Ren and Wu present as secondary hidden stems. Shen is a Yang-polarity branch, pairing only with Jia, Bing, Wu, Geng or Ren within the sexagenary cycle, and it governs the seventh lunar month, the start of autumn, and the direction southwest within the compound directional scheme that combines pairs of branches for the eight intermediate points. In BaZi astrology a chart with Shen prominent is read through the Monkey's traditional associations of cleverness, versatility and wit, combined with the Metal phase's own associations of sharpness and decisiveness, together read as an inventive, quick-adapting temperament that the tradition also cautions can tip into restlessness or trickery if the chart lacks a stabilising Earth influence.

Beyond the animal it carries, a branch enters three fixed sets of relations that the almanac and the fate-calculation tradition use constantly. Shen belongs to the trio Shen, Zi and Chen, one of the four groups of three branches spaced four apart which are read as combining into Water. It clashes with Yin, the branch six places away, and it forms one of the six harmonies with Si. 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 Shen names a period of two hours as well as a year and a month; they mark the twelve directions of the compass, Shen standing at west-southwest; 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.

Shen opens the autumn in the month assignment. Its clash with Yin is one of the six, and because Yin opens the year the Shen and Yin axis divides the year in half, which is a structural fact rather than an interpretive one: the twelve branches applied to twelve months put any pair six apart six months apart.

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