The sixty-year cycle of heavenly stems and earthly branches.
The Sexagenary Cycle pairs ten Heavenly Stems with twelve Earthly Branches, advancing both together so that the same combination returns only every sixty steps. It is two interlocking wheels — like gears of different sizes — generating a long, non-repeating count used for years, days, and hours alike.
Ganzhi unlocks combinatorial timekeeping: a small set of symbols producing a far larger ordered sequence, the same principle that drives odometers and cyclic counters. It is the quiet engine beneath nearly every Chinese temporal system, proof that two modest cycles, offset, can measure time with elegant economy.