塞万提斯《堂吉诃德》：

 to do good to boors is to throw water into the sea. 

施恩于小人，无异倒水于大海。

原文：

Seeing himself served in this way, Don Quixote said to his squire, "I have always heard it said, Sancho, that to do good to boors is to throw water into the sea. If I had believed thy words, I should have avoided this trouble; but it is done now, it is only to have patience and take warning for the future."

堂吉诃德狼狈不堪，对侍从说道：

“桑乔，我常听人说：‘施恩于小人，无异倒水于大海。’要是听了你的话，我就不会吃这么大的苦头了。事已至此，只好认了，作为今后行事的教训吧。”