Heavenly Stems 天干

The Heavenly Stems are a cycle of ten characters — Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui — which the tradition reads as the five elements in their yang and yin forms. Jia is yang Wood and Yi is yin Wood; Bing is yang Fire and Ding yin Fire, and so on. They appear on oracle bones from the Shang dynasty, where they were used to name days, and they are the older half of the calendar system.

Stems are the visible, active layer of a chart. They carry one element each with no hidden content, so a reader sees at a glance what is on the surface; the branches beneath them are where the complications live. The ten-stem cycle is also what makes the sexagenary cycle sixty rather than twelve: ten stems against twelve branches, matched only yang-to-yang and yin-to-yin, gives sixty combinations.

Every pillar printed by the chart tool has a stem on top, and the year stem is what turns a Goat year into a Fire Goat year on the 2027 pages.

• See the stems in a real chart
• The 2027 year stem and all twelve signs