The Ten Heavenly Stems (天干, Tiangan) are the foundational layer of the BaZi Four Pillars chart. They come from the Five Elements split into Yang and Yin polarities — five elements × two polarities = ten stems — and they form the top row of every pillar. Where the Earthly Branches below them describe the hidden structure of a life, the stems are what is visible: how a person presents to the world, how external events unfold, and what is consciously expressed.

Yang and Yin, element by element

Each element contributes two stems, one of each polarity, and they are not simply the same energy twice. Jia (甲) is the great tree and Yi (乙) the flowering vine; Bing (丙) is the sun and Ding (丁) the candle flame; Wu (戊) is the mountain and Ji (己) the garden soil; Geng (庚) is the axe and Xin (辛) the jewel; Ren (壬) is the ocean and Gui (癸) the rain.

That difference matters in a reading. The two stems of an element are not interchangeable: they support a chart differently, they respond to the same season differently, and they behave differently as a Day Master. Each article below sets out its stem's core identity, its relationships with the other elements, and where it appears in feng shui and in the annual stars.

Where the stems are used

The stems are not an astrology-only device. They label the days and hours of the Chinese calendar and head the years of the sixty-year Jiazi cycle, and the annual afflictions and the flying star charts elsewhere in the knowledge base are dated by them. Learning the ten as a set — element, polarity, season, direction — is the quickest way into reading a chart by hand, and the section on Earthly Branches completes the other half of it.