Heavenly Stems (Tian Gan)

In one line: The Heavenly Stems are 10 ancient "codes" used by the ancients to mark days and years.

What is it?

You've probably heard "Jia, Yi, Bing, Ding" — these are the first 4 of the Heavenly Stems. There are 10 in total:

Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui

Without Arabic numerals, the ancients used these 10 characters in rotation to mark time. These symbols are called Heavenly Stems.

Why are they important?

Each stem has a Five Element attribute and a Yin/Yang attribute:

Stem	Element	Yin/Yang
Jia	Wood	Yang
Yi	Wood	Yin
Bing	Fire	Yang
Ding	Fire	Yin
Wu	Earth	Yang
Ji	Earth	Yin
Geng	Metal	Yang
Xin	Metal	Yin
Ren	Water	Yang
Gui	Water	Yin

How to read it in your BaZi chart?

At the moment you were born, each of year, month, day, and hour has one Heavenly Stem — 4 in total, called the "stem portion" of the Four Pillars (四柱).

For example, if your Day Pillar is "Jia Chen", then "Jia" is your Day Master (Ri Zhu), representing "you yourself".

The whole BaZi analysis revolves around the Day Master: is it strong or weak? What does it favor? What does it avoid?

Common Misconceptions

❌ "Heavenly Stems are the Five Elements (Wu Xing)" — the stems are symbols; the elements are attributes. ❌ "10 stems stand for 10 days" — the ancients did use stems for day-counting, but BaZi analysis is more complex. ❌ "More stems = better" — they need to be read together with the branches to be meaningful.

📜 Classical source: Di Tian Sui (《滴天髓》) "Jia Wood reaches to heaven; to be born, it needs Fire" 🔗 Next lesson: Earthly Branches (Di Zhi)