一个没有记忆的国家是没有未来的国家。

The world is full of poetry. The air is living with its spirit; and the waves dance to the music of its melodies, and sparkle in its brightness.

在数学中，提出问题的艺术必须比解决问题更有价值。

把肉扔在饿虎出没的小路上，祸患就无可挽救了。主动招惹麻烦，怎么可能平安无事。