Tang poet Yuan Zhen
元稹 made Mount Wu the ultimate metaphor for unmatchable love in his
离思 ('Parting Thoughts'), example 2 above. The deeper layer is the Warring-States 《
高唐赋》 by
宋玉, where the King of Chu meets the goddess of Wushan in a dream — giving Chinese the euphemism
巫山云雨 ('Wushan clouds and rain') for sexual union.