From Bai Juyi's (
白居易) Tang-dynasty narrative poem 《
琵琶行》 (Song of the Pipa). The full couplet is 『
同是天涯沦落人,
相逢何必曾相识』— 'we are both wanderers cast to the world's edge; why must we have met before to feel close?' Bai wrote it after hearing a former courtesan play pipa on the Xunyang River, recognizing in her fate a mirror of his own demotion.