人类最伟大的追求是知道必须做什么才能成为一个人。
The greatest human quest is to know what one must do in order to become a human being.
To travel is to write, and to write is to travel.
贫贱是苦难的境界，能很好地居于其境者就苦中有乐；富贵是快乐的境地，不能很好地对待富贵的人便会乐极生悲。
指事物之间相互依存、相互制约的关系。