Origins of Symbols · Calendars and Bazi
FDL-019
How the Heavenly Stems and Earthly Branches Recorded Time
- Author
- Editorial Board, Orphic Meridian Association
- Date
- 2026-01-14
- Reading time
- 3 min
One of the earliest important uses of the stems and branches was to give days a continuous sequence. The ten stems and twelve branches advance together—Jia with Zi, Yi with Chou—until both return to the start after sixty steps.
Why there are sixty rather than 120 pairs
The two lists do not combine freely. Their least common multiple is sixty, and parity remains aligned, so Jia never pairs with Chou. The result works like a rotating serial number independent of a ruler's regnal year. Oracle-bone inscriptions already show a mature use of stem-branch day notation.
One notation entered several time scales
The cycle can number days and years; rules also assign stems and branches to months and double hours. Four Pillars writes year, month, day, and hour as four pairs—the “eight characters.”
The same symbols do not imply the same calculation. Year requires a boundary convention; month follows seasonal nodes and the year stem; day requires a continuous day count; hour depends on the day stem and hour branch. A zodiac animal or Gregorian year cannot reconstruct the full chart.
Animals are one later correspondence
The twelve animals make branch years memorable, but Zi, Chou, and the other branches already served time and direction. Historical analysis should recover the stem-branch notation before adding animals, phases, or Ten Gods.
Keep the calculated layer visible
A Four Pillars report should retain the civil date and time, conversion rules, and resulting four pairs. If it displays only symbolic labels, a reader cannot tell whether disagreement comes from a year boundary, solar-term transition, day-count convention, or hour calculation.
The four pillars also depend on one another in different ways. The month stem uses the year stem; the hour stem uses the day stem. Showing intermediate results makes later interpretation auditable instead of treating the eight characters as unexplained input.
Next compare Lichun and Lunar New Year as year boundaries and solar terms as month-pillar boundaries.