THE TWO CYCLES ADVANCE TOGETHER
Why ten and twelve become sixty
Start with 갑자 (Gap–Ja). Move one step in both rows and the next pillar is 을축 (Eul–Chuk), then 병인 (Byeong–In). Because the cycles have lengths ten and twelve, they return to their shared beginning after sixty valid pairs.
HEAVENLY STEMGap갑Ja자EARTHLY BRANCH
+NEXT STEMEul을Chuk축NEXT BRANCH
→Yang meets yang; yin meets yin.
That parity rule removes the impossible cross-pairs and keeps the two sequences synchronized.
Year, month, day, and hour each receive a pair.
Together the four upper stems and four lower branches form the eight characters of Saju Palja.