历史这个游戏的玩家一般都是社会的最上层和最下层，占大多数的中间层次只有在台下看戏的份。

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.

"The only way to learn mathematics is to do mathematics."

可持续性不是一种选择；它是我们对后代的责任。