The power of mathematics lies in its generality and abstraction.
数学的力量在于它的普遍性和抽象性。
The great secret that all old people share is that you really haven't changed in seventy or eighty years. Your body changes, but you don't change at all. And that, of course, causes great confusion.
It is easier to fight for one's principles than to live up to them.
文学是赋予无形以形式的艺术。