北城以北深海未眠南城以南蓝天未变
[bĕi chéng yĭ bĕi shēn hăi wèi mián nán chéng yĭ nán lán tiān wèi biàn]
A rich metaphor describing the constancy and continuity of places separated by direction. It contrasts deep sea with clear sky, symbolizing contrasts in emotions or situations.