“饮水思源”，字面意思是“喝水的时候，要想到水是从哪里来的（When drinking water, one should not forget its source）”。

出自南北朝时期诗人庾信的《徵调曲》，“落其实者思其树，饮其流者怀其源（When eating fruits, one should think of the fruit trees; when drinking water, one should think of the source of the river.）”。

庾信被迫在北朝客居二十多年，他常常思念故土，写文章说自己喝到河里的水就想到水的源头，以此抒发对于南朝的情怀。后世将原文写为“饮流怀源”或“饮水思源”，比喻不忘本、知感恩（one should never forget his origin and always be grateful）。可以翻译为“gratitude for the source of benefit；never forget where one's happiness comes from”。

例句：

他是一个懂得饮水思源的人。

He never forgets his origin and always remembers the past kindness that he received.