无论多么聪明的人，在他年轻时都曾说过或做过一些事情，后来回想起来会感到不快，以至于如果可能的话，他会很高兴地从记忆中抹去。
There is no man, however wise, who has not at some period of his youth said things, or lived in a way the consciousness of which is so unpleasant to him in later life that he would gladly, if he could, expunge it from his memory.
数学是一种创造性的努力，就像艺术或音乐一样。
历史的任务不是评判，而是理解。
Success is the sum of small efforts, repeated day in and day out.