Sixty-cycle

Meaning

The sixty-cycle, 六十甲子 liùshí jiǎzǐ, “the sixty Jia Zi”, pairs the ten Heavenly Stems with the twelve Earthly Branches, one step at a time: Jia with Zi, Yi with Chou, Bing with Yin, and so on to Gui Hai, the sixtieth, after which Jia Zi comes round again. Ten and twelve meet again only after sixty steps, and a yang stem only ever meets a yang branch, so the cycle holds sixty pairs rather than a hundred and twenty. Each pair is a pillar: a stem over a branch, a phase in one polarity over an animal.

China has named its days by these sixty since the Shang dynasty, and its years, months and double hours by them too; a birth is four of them, the four pillars and eight characters of BaZi. Each pillar has a character of its own, from its two phases and the way they meet, Jia Zi a tree over water, Bing Wu fire over fire, and each two in a row share a Na Yin, an image and a sound.

The cycle is the thread that ties the Chinese languages together: the zodiac’s animal is the branch of the year’s pillar, BaZi reads all four pillars of a birth, the Calendar names each day by its pillar, and the tradition measures a life by it too, sixty years being one full turn.

In practice

• In BaZi, a birth is four pillars of the cycle, and time is more of them: the luck pillars step through the cycle from the month pillar, ten years each, and every year, month and day brings its own.
• In Chinese astrology, the year’s pillar gives the year animal and its phase, sixty kinds in all: the Metal Horse of 1990 and the Fire Horse of 2026 are Geng Wu and Bing Wu.
• In the Calendar, every day has its pillar, and its animal is the branch’s.
• The six weeks: the cycle falls into six ten-day weeks, each opened by a Jia; each pairs its ten stems with ten branches and leaves two out, the empty branches.
• A sixtieth birthday: after sixty years the pillar of the birth year returns, a turn the tradition calls 花甲 huājiǎ, celebrated in Japan as kanreki and in Korea as hwangap.

Across traditions

• In Japan, Korea and Vietnam the same sixty are the eto, the yuksip-gapja and the lục thập hoa giáp; Kōshien Stadium, opened in 1924, a Jia Zi year, still carries the pillar in its name, 甲子園.
• In Chinese history years are named by their pillar: the Xinhai Revolution is the revolution of 1911, a Xin Hai year.
• In the Maya calendar, the 260-day count meshes thirteen numbers with twenty day names in the same way, two wheels turning together until they meet again.
• In Mesopotamia, sixty was a base for counting, which gave the hour its sixty minutes and the circle its 360 degrees; the Chinese sixty is a meeting of ten and twelve rather than a base.

Origin and history

The cycle is among the oldest things in Chinese writing. The oracle bones of the late Shang dynasty, around 1250–1046 BC, date their days by stem and branch, and one bone carries the whole table of sixty; the count of days has run on since, without a break as far as the records can check. Tradition credits Da Nao, a minister of the Yellow Emperor, with making the Jia Zi. Years were named by the cycle from the Han dynasty, and Sima Qian’s Shiji and Ban Gu’s Hanshu explain the names of the stems and branches as the stages of growing things; months and double hours took their pillars by the rules of the five tigers and the five rats, and by the Tang dynasty a birth could be read as pillars of the cycle.

How Ulune calculates it

Ulune numbers the sixty from 0, Jia Zi, to 59, Gui Hai: a place’s stem is the place modulo 10, its branch the place modulo 12, and a stem and a branch of the same polarity meet at six times the stem less five times the branch, modulo 60. A year’s pillar is counted from Jia Zi in 1984, turning at Lichun; a month’s, twelve a year, from Bing Yin in the Tiger month of 1984; a day’s, from the Julian day number plus 49, which makes 1 January 2000 Wu Wu; an hour’s, twelve a day, from the day’s. A pillar’s name is its stem’s and its branch’s, Jia Zi, and its picture their phase, polarity and animal, the Yang Wood Rat.

Correspondences