你可以想错，但无论如何要为自己思考。
Think wrongly, if you please, but in all cases think for yourself.
I went to the woods because I wished to live deliberately. I wanted to live deep and suck out all the marrow of life, to put to rout all that was not life.
Logic is the foundation of all mathematical reasoning.
宁要知识不要财富，因为一个是短暂的，另一个是永恒的。
Lack of money is the root of all evil.
The study of mathematics is like air or gravity – it’s everywhere, even if you don’t see it.