Ba Zi, the Four Pillars of Destiny, reads a birth moment as four pillars, year, month, day and hour, each a Heavenly Stem stacked over an Earthly Branch, the same sexagenary building blocks Chinese Astrology's own page describes. A date-only reading gives the year, month and day pillars; the hour pillar needs an exact birth time and is not included without one.

History

The stem and branch cycle underneath Ba Zi is the same sexagenary system attested from Shang dynasty oracle bone inscriptions onward, already described in full on this atlas's Chinese Astrology page. Reading a person's birth moment as four separate stem-and-branch pillars rather than as a single year animal is a later, more developed application of that older cycle: scholars of Chinese esoteric history generally trace systematic Four Pillars fortune-telling to the Tang and Song dynasty period, with the tenth century figure Xu Ziping frequently credited as a key systematizer of the method, which is why the practice is also known by the alternate name Zi Ping in Chinese sources. The technique layers the older Wu Xing five phase cosmology on top of the stems and branches, reading the balance and interaction of the five phases across all four pillars as the core of a Ba Zi analysis.

The Four Pillars

Year, Month, Day and Hour: each pillar pairs one of the ten Heavenly Stems with one of the twelve Earthly Branches. The year pillar is taken from the solar year beginning at Lichun (roughly February 4th), not the lunar new year; the month pillar from the solar term the birth falls in rather than the calendar month; the day pillar, read as the person's core self in most Ba Zi practice, from a continuous stem-and-branch day count; and the hour pillar, needing an exact birth time, from the two-hour period (shichen) of birth.

How A Reading Is Constructed

A date-only reading computes the year, month and day pillars from the birth date, the year taken from the solar year that begins at Lichun and the month from the solar term it falls in rather than from the calendar month, and reads the balance of the five phases (Wu Xing) across the resulting stems and branches. The hour pillar, which needs an exact birth time, is not included in a date-only reading and is added once a birth time is provided, matching the report item's own stated scope.

Where To Read More

• JiaJia, the first Heavenly Stem.
• YiYi, the second Heavenly Stem.
• ZiWater BranchesZi, the first Earthly Branch, named by the Rat.
• ChouEarth BranchesChou, the second Earthly Branch, named by the Ox.