In its preface
宋玉 tells King Xiang of Chu how an earlier king dreamed at Gaotang of the goddess of Mount Wu, who said that she was
旦为朝云，
暮为行雨 'morning clouds at dawn and passing rain at dusk'. From her come
云雨 and
巫山云雨 as polite words for lovemaking, the phrase
朝朝暮暮 'every morning and every evening', and the
巫山 of
除却巫山不是云.
