Jia (甲) — Yang Wood

Jia heads the Ten Heavenly Stems and represents yang wood — the rising, structural, pioneering quality of wood. Classical texts compare it to a tall tree (大林之木): straight trunk, deep roots, branches reaching to heaven. As a Day Master it gives leadership instincts, principled bearing, and a pioneering temperament that breaks new ground but resents being directed.

Jia is favored by water for nourishment and by metal for shaping, but fears flood (too much water rotting the roots) and dislikes earth too dry. The classical pairing 甲己合化土 (Jia-Ji union transforming to earth) is the first of the five stem combinations, signaling marriage between heaven's yang wood and earth's yin soil.