使变量可变很容易。控制恒定的持续时间是诀窍。

When you attack coal, you attack middle America.

Life is really simple, but we insist on making it complicated.

"We are all haunted by the past, and the past is always present."

The strength of the pack is the wolf, and the strength of the wolf is the pack.

The only way to improve is to challenge yourself against the best.

The same principles which at first view lead to skepticism， pursued to a certain point， bring men back to common sense.