The prime meaning of the word kan or "stem" is a strong and powerful tree trunk, representing the Yang or male principle; the word chih or "branch" originally meant a weak and tender twig, thus representing the Yin or female principle.
例如「干」的本義是強而有力的「樹幹」，代表「陽」；而「支」的本義是柔弱的「樹枝」，代表「陰」。