From 《
离骚》 (Lí Sāo, 'Encountering Sorrow') by Qu Yuan (
屈原, Warring States, state of Chu). The full couplet:
长太息以掩涕兮,
哀民生之多艰 — 'I heave a long sigh and hide my tears, mourning the many hardships of the people's lives.' The single most-quoted line from Chinese literature's first great lyric poem.