学习数学的唯一方法就是做数学。
The only way to learn mathematics is to do mathematics.
In our reasonings concerning matter of fact， there are all imaginable degrees of assurance， from the highest certainty to the lowest species of moral evidence.
Your time is limited, so don't waste it living someone else's life.
批判的语言是不够的，它必须伴随着可能性的语言。
过去从未死去，它甚至还未过去。
Man is not logical and his intellectual history is a record of mental reserves and compromises. He hangs on to what he can in his old beliefs even when he is compelled to surrender their logical basis.