From
白居易《
琵琶行》(Bai Juyi, Tang, 816):
同是天涯沦落人,
相逢何必曾相识 (We are both fallen wanderers at the world's edge — to meet, why must we have been acquainted before?). Bai, demoted to Jiangzhou, encountered a former Chang'an courtesan playing pipa on a moonlit boat; their shared decline needed no introduction. One of the most quoted couplets in the Chinese canon.