自然和历史是地理知识的两个重要来源。

It is common sense to take a method and try it. If it fails, admit it frankly and try another. But above all, try something.

释义：一个人即使一生都很聪明，也可能在某个时刻犯糊涂。

真正的旅程不在于发现新的风景，而在于用新的眼光去看。