Day pillar

Meaning

The day pillar, 日柱 rìzhù, is the third of the four pillars: the day of birth, named by its place in the sixty-day cycle, Jia-Zi, Yi-Chou and so round to Gui-Hai. It is the heart of the chart. Its stem is the Day Master, the self every other character is read against; its branch, sitting directly under the self, is the partner palace, the seat of the closest bonds.

The tradition reads the pair as a person and what they stand on in private: the stem as who one is, the branch as one’s home ground, the partner and the life shared most closely. A Jia Day Master on Zi, a tree on water, reads differently from the same Jia on Wu, a tree over fire, and each of the sixty day pillars has a character of its own, which the pages of the sixty pillars describe.

Because the days follow each other through the cycle without a break, the day pillar is also the one that changes fastest: two people born a day apart share the year and almost always the month, but not the day. It is what makes a chart one’s own rather than one’s year’s or month’s.

In practice

• On the board, the day pillar stands second from the left in the classical order; its stem is outlined as the Day Master, its branch’s hidden stems read as gods like any other.
• The empty branches: the two branches the day pillar’s ten-day week leaves out are the chart’s empty branches.
• Stars read from it: the Day Master is the base of the Nobleman, the Academic star, the Prosperity star, the Golden Carriage and the Sword Edge; the day branch, with the year’s, of the four trine stars.
• Two people: the Relationship lens compares the two day branches, the partner palaces, and what each Day Master is to the other.
• The turn of the day: Ulune turns the day at 23:00 by default, the start of the Rat hour, as the Zi Ping school counts; midnight and the split Rat hour are options for readers of other schools, and a birth within five minutes of the turn is marked uncertain.
• In Chinese astrology its branch is the day animal, the self with those closest.

Across traditions

• In Japan and Korea it is the nitchū of Shichū Suimei and the ilju of saju; in Korea the day pillar alone, the ilju, is a popular portrait, “a Gapja day”, the way a Sun sign is in the West.
• In Western astrology the nearest picture is the Moon, which also moves fastest and speaks of private life and closeness: a part of the chart that two people born a few days apart do not share.

Origin and history

The sixty-day count is the oldest in China: the Shang dynasty’s oracle bones, more than three thousand years ago, already date their days by stems and branches, and the count has run on, as far as the records can check, ever since. Li Xuzhong, under the Tang, read the day as one of three pillars, and Xu Ziping, in the 10th century, made the day’s stem the self; the classics after him, from the Yuanhai Ziping of the Song to the San Ming Tong Hui of the Ming, read the day branch as the palace of the spouse, the place where the Day Master sits. The question of when the day turns, at the Rat hour’s start or at midnight, has long divided the schools, and still does.

How Ulune calculates it

Ulune reads the day on the birthplace’s own clock: true solar time by default, the Sun’s own time at that longitude; local mean time or the civil clock on request. The day pillar is the day’s Julian day number plus 49, modulo 60, the count that makes 1 October 1949 Jia-Zi and 1 January 2000 Wu-Wu, as published. With the default rule, a birth from 23:00 takes the next day’s pillar; with the split Rat hour, it keeps the day and takes the next day’s Rat hour; with midnight, both stay.

Correspondences