学习数学的唯一方法就是做数学。

The right of nature... is the liberty each man hath, to use his own power, as he will himself, for the preservation of his own nature; that is to say, of his own life.

智者从敌人那里学到的比愚者从朋友那里学到的还要多。

粮食富裕，人们就知道礼节；衣食丰足，人们就懂得荣辱。