Bazi — the Four Pillars
Chinese, the Zi Ping method, attributed to Xu Ziping
The sexagenary cycle that Bazi rests on labels days on Shang oracle bones from around 1250 BCE — one of the oldest continuous calendrical devices in the world. The birth-chart method of reading the four pillars (year, month, day, hour) is credited to Xu Ziping; the traditional teacher-to-student lineage is recorded only in a much later Ming-dynasty miscellany, so its early history is thin.
What it measures
Four pairs of a heavenly stem and an earthly branch — the sexagenary signatures of the year, month, day and hour of birth — from which the five elements are balanced. The year begins at Li Chun (a solar term, not lunar New Year) and the hour is taken in true local solar time.
Where practitioners disagree
- Where does the year begin?
At Li Chun, the solar term near 4 February (ours) — or at lunar New Year, in some popular practice
The day boundary and the true-solar-hour rule are also debated.
This engine: At Li Chun, computed from the Sun's true longitude; the hour in true local solar time.
Sources
- Xu Ziping (attrib.), Yuan Hai Zi Ping