I was very, very thorough, making sure I really understood how that telescope worked, and that it was working properly. I was quite convinced that I wasn't clever enough to be in Cambridge and would be thrown out at some stage. My policy was to work as hard as I could so that I'd know I'd done my best. We now label this as impostor syndrome, but we didn't recognise, and certainly didn't name it, back then.

Well, yes, no, I certainly visualise … it was really … I had to have a very good idea of the geometry – that was crucial. Spacetime geometry so it's not three dimensions, you have to think of the whole four dimensional spacetime, and I get sort of used to thinking about four dimensions and using various tricks to get the picture properly. I do most of my thinking in visual terms, and I'm a very visual thinker rather than writing down equations.

I find that you’re a completely different person as a maker than you are as a listener. That’s one of the reasons I so often leave the studio to listen to things. A lot of people never leave the studio when they’re making something, so they’re always in that maker mode, screwdriving things in - adding, adding, adding. Because it seems like the right thing to be doing in that room. But it’s when you come out that you start to hear what you like.

For me, to be a writer is to acknowledge the secret wounds that we carry inside us, the wounds so secret that we ourselves are barely aware of them, and to patiently explore them, know them, illuminate them, to own these pains and wounds, and to make them a conscious part of our spirits and our writing. A writer talks of things that everyone knows but does not know they know.

When I am on my deathbed, and I am thinking back on my life, I am absolutely certain that the thing I will be thinking about is holding my daughters' hands and taking them to the park. It will not be some speech I gave or some legislation that I passed. I am positive about that. And so if you keep that in mind, then you have to invest accordingly.

What makes me proudest about them is that they also don't get cynical about it. They have not assumed because their side didn't win, or because some of the values that they care about don't seem as if they were vindicated, that automatically America has somehow rejected them or rejected their values.

I was raised by a heroic single mom, wonderful grandparents -- made incredible sacrifices for me. … But I sure wish I had had a father who was not only present, but involved. Didn't know my dad. And so my whole life, I've tried to be for Michelle and my girls what my father was not for my mother and me. … I want to be a better father, a better husband, a better man.

One of the things that Michelle and I are proud of is that we came through the White House with our souls intact. Everybody has heard: Power corrupts. I do think if you are placed in such an artificial situation, and your office has great importance, there is a tendency for people to want to please you. To not be as honest with you. We fought against that.

I believe in this country. I believe in the American people. I believe that people are more good than bad. I believe tragic things happen, I think there's evil in the world, but I think that at the end of the day, if we work hard, and if we're true to those things in us that feel true and feel right, that the world gets a little better each time.

It's hard - truthfully the main thing other than work is just making sure that I'm spending enough time with michelle and the girls. The big advantage I have is that I live above the store - so I have no commute! So we make sure that when I'm in DC I never miss dinner with them at 6:30 pm - even if I have to go back down to the Oval for work later in the evening. I do work out every morning as well, and try to get a basketball or golf game in on the weekends just to get out of the bubble.