Well, I've ruffled a few feathers at all the institutions I've led. But I think that's part of leadership.

I've seen, all too often in my career, people coming in to lead agencies and organizations and trying to impose change from the top down. Never works. You never have enough time.

I had no difficulty as Secretary of Defense moving from the Bush administration to the Obama administration.

One of the big changes in the Congress since I first came to Washington is that all of these folks go home every weekend. They used to play golf together; their families got to know each other, go to dinner at each other's homes at weekends - and these would be people who were political adversaries.