You really struggle to be a successful empire if you are also the world's biggest debtor.

I think that it is important to be gregarious, and that friendships are not just a leisure pursuit, that they are an integral part of what it is to be human, and one does better work if one has a circle of friends that is active.

Collaboration is risky. If it fails, if the occupation is wound up prematurely and the bad guys come back to power, you might find yourself in some serious trouble.

As a teacher, my strategy is to encourage questioning. I'm the least authoritarian professor you'll ever meet.

For 500 years the West patented six killer applications that set it apart. The first to download them was Japan. Over the last century, one Asian country after another has downloaded these killer apps- competition, modern science, the rule of law and private property rights, modern medicine, the consumer society and the work ethic. Those six things are the secret sauce of Western civilization.

It's all very well for us to sit here in the west with our high incomes and cushy lives, and say it's immoral to violate the sovereignty of another state. But if the effect of that is to bring people in that country economic and political freedom, to raise their standard of living, to increase their life expectancy, then don't rule it out.

You really struggle to be a successful empire if you are also the world's biggest debtor.