Heavenly Stems

The 10 Heavenly Stems (天干 Tiān Gān) cycle through five elements × two polarities: Jiǎ (Yang Wood), Yǐ (Yin Wood), Bǐng (Yang Fire), Dīng (Yin Fire), Wù (Yang Earth), Jǐ (Yin Earth), Gēng (Yang Metal), Xīn (Yin Metal), Rén (Yang Water), Guǐ (Yin Water). Each pillar (Year, Month, Day, Hour) has one Heavenly Stem and one Earthly Branch. The Heavenly Stem expresses the visible, outward energy of that pillar.