The Twelve Hours

십이시 · 十二時

The twelve two-hour blocks that decide your hour pillar.

The day is divided into twelve blocks of two hours, each ruled by one earthly branch, beginning with the Rat hour at 23:00.

Because the blocks are two hours wide, a birth recorded near a boundary is fragile: half an hour of clock error, or an uncorrected timezone, moves you into the neighbouring branch and changes a quarter of your chart.