From
王勃's early-Tang poem 《
送杜少府之任蜀州》 (Seeing Off Prefect Du on His Way to Shu). The couplet reads:
海内存知己,天涯若比邻 - 'Within the four seas, a true friend exists; at the ends of the earth, we are as next-door neighbors.' Written as a farewell to a friend taking a post in faraway Sichuan, remarkably upbeat for a Tang farewell poem.