The circumstances of the world are continually changing, and the opinions of man change also; and as government is for the living, and not for the dead, it is the living only that has any right in it.

自然实验是理解现实世界中因果关系的强大工具。

The world needs responsible miners who understand the value of both minerals and the planet.

地球上唯一伟大的是人，人身上唯一伟大的是心灵。