In the original work, the second line was actually "A glance can topple a city, a second glance can topple a nation," only here he changed it to the word "dance." Of course, even the word for "glance" here does not mean patronage, but rather "to look upon."
Therefore, translated in full, the verse means: There is a beauty in the northern lands, with a peerless countenance unmatched in all the world, standing aloof from the mortal dust. Yet even though such a beauty often brings the calamity of toppled cities and ruined nations, one cannot afford to miss the chance to win her. After all, such exquisite beauty is a rare encounter in this world, never to be found again!
According to the *Book of Han: Biography of the Imperial Relatives, Part 1*, during a palace banquet, Li Yannian performed a dance and sang this poem. Upon hearing it, Emperor Wu of Han could not help sighing: "Is there truly such a beauty in this world?" The Emperor's elder sister, Princess Pingyang, then recommended Li Yannian's younger sister. When Emperor Wu summoned her for an audience, she proved indeed to be exquisitely beautiful and skilled in dance. From then on, Li Yannian's sister became Emperor Wu's favored consort, Lady Li, and was regarded as one of his most beloved among all his wives and concubines.
Chapter 49