生活的目的不是快乐，而是有用、光荣、富有同情心，让你活得有意义、活得好。

Digital won't kill paper; complacency will.

The greatest threat to our planet is the belief that someone else will save it.

The great cause of the prosperity of the country is liberty—liberty in the economic system.

You have to believe in yourself when no one else does.