You can't go through life with a catcher's mitt on both hands. You need to be able to throw something back.

The problem is not that there are problems. The problem is expecting otherwise and thinking that having problems is a problem.

The historian must be impartial, but not indifferent.

任何在科学探索中追求即时实用价值的人，可以确信他的追求是徒劳的。

The international system is inherently competitive, and states are constantly trying to outmaneuver each other.