The moment you stop learning is the moment you start failing.
孔子说:“遇到可以说的人却不说,就会失去可与说话的人;遇到不可说的人却说了,就是说话冒失。聪明的人既不去可交谈的人,也不言谈冒失。”
The mathematician does not study pure mathematics because it is useful; he studies it because he delights in it and he delights in it because it is beautiful.