Yin and yang

Yin and yang describe two complementary, relative poles within the same thing. Each stem and branch has a yin/yang value; BaZi Ten Gods also distinguish “direct” vs. “indirect” by whether the other stem matches the Day Master’s polarity.

In Liu Yao and the Zhou Yi, yang lines (—) and yin lines (--) form hexagrams; in reading, yin/yang is not only a symbol but also a hint of motion vs. stability, firmness vs. yielding, and related tendencies.