登山不以艰险为止，则必臻乎峻岭矣。积善不以穷否而怨，则必永其令闻矣。
出自《抱朴子·外篇·广譬》。登山的时候，不因为山路艰险便停止，就一定能够到达山顶。积善也不会因为穷困而埋怨，便能够使自己获得长久的美名。
The most important thing in mathematics is to understand the concepts, not just to memorize formulas.
For the past 33 years， I have looked in the mirror every morning and asked myself: 'If today were the last day of my life， would I want to do what I am about to do today？' And whenever the answer has been 'No' for too many days in a row， I know I need to change something.
文学是对人类灵魂在黑暗与光明中的探索。
最好的科学是双手弄脏而头脑清醒时完成的。