Heavenly Stems (Tiangan 天干)
The ten heavenly stems (tiangan 天干) are the series of ten signs that express the five elements doubled by yin and yang. Each element appears twice, first yang then yin: Jia and Yi (Wood), Bing and Ding (Fire), Wu and Ji (Earth), Geng and Xin (Metal), Ren and Gui (Water). In the calendar these ten stems pair with the twelve earthly branches to form the sixty-year cycle. The stem brings the elemental quality and polarity of each pillar.
Five elements, two faces
Count with me: five elements, each in an active then a receptive version, which makes ten. A yang Wood is the tree that grows straight and splits the earth; a yin Wood is the supple vine that coils. Same matter, two gestures. Your day stem, in the Ba Zi, is exactly that face, the heart of who you are.
The breath that animates the pillar
If the branch is the ground, the stem is the sky leaning over it. You always read the two together, never one without the other. This dance of stem and branch, repeated at each pillar, gives the Ba Zi its fine texture, far richer than your year animal alone.
Sources
- , Feng Shui and Destiny (1995)