自由不止一种……自由去做和自由免于。在无政府状态的日子里，是自由去做。现在你被给予了自由免于。不要低估它。
There is more than one kind of freedom... Freedom to and freedom from. In the days of anarchy, it was freedom to. Now you are being given freedom from. Don't underrate it.
Mathematics is the language in which the universe writes its deepest secrets.
Optimism is a learned skill. Once you learn it, you can improve your life in every way.
【讲解】：有了过错，别人都能看到；改了，人们都会敬仰他。