《淮南子·泰族训》
假若在黑暗的房间里挖个小孔，能让他看见外面下雨的雨点滴落，他都会快乐地笑起来，更何况敞开房门打开窗户，让他能看到光明世界呢！
以目之无见，耳之无闻，穿隙穴，见雨零，则快然而叹之，况开户发脯，从冥冥见炤炤乎！
If a small hole is dug in the dark room so that he can see the raindrops falling outside, he will laugh with joy, let alone if the door and windows are opened so that he can see the bright world!