Being a father can 'unreason' your worldview, or at least make it very flexible, and that can create all sorts of fun and insights. It's sad that children's open-eyed wonder and sense of play begin to fade as they approach adolescence. One grand function of fathering is to keep the fading to a minimum.

Kristina, my wife, and I thought about this one day when the kids were, of course, watching television. And we took a big blanket and put it in the backyard and said, 'Let's go out on our back and look at the sky and call it sky television.' We saw all kinds of things.

I think I would have written more books if I'd had fewer kids or had them earlier, but I think the books in general would have had a little less spark to them.

I have a daughter, Catherine, aged 30. I have a 9-year-old son, Nathaniel, a 7-year-old son, Ridley, and a 6-year-old daughter, Truma. I'm 68. The age gap between the younger kids and me is not something I think about much because I feel physically about like I did when I was 40, or at least, I think I do.