In How to Live (Reviews, Sept. 29), New Yorker writer Henry Alford talks to the elderly in search of wisdom.

What was the inspiration behind this book?

I'm fascinated by the idea that humans are one of the few species whose average lifespan exceeds the age at which they procreate. Why, what's the evolutionary reason? I think it's because old people are like living libraries... and we as a culture really overlook that.

How did you go about selecting the types of people you were interested in interviewing?

I made lots and lots of lists of people I was interested in, and then I winnowed it down. I didn't want anyone who gets a lot of opportunity to talk, like the Dalai Lama. I didn't want to talk to anyone who didn't want to talk to me, like Thomas Pynchon or J.D. Salinger. I didn't want to talk to anyone who had some affiliation with an organization that would curb their freedom to speak, so that knocked out a lot of clergy or Sen. Robert Byrd. I was left with maybe 100 names... and then I just talked to hundreds of people informally.

Your mother and stepfather were on that list of potential interviewees from the beginning, and then they broke up shortly after you talked to them. What was that like?

What transpired in those interviews was freakish and unexpected. Now I know how dentists feel when they see a mouth full of plaque. As a human, you think, “Oh, how sad,” but as a professional writer, you think, “Ka-ching.” It's not at all the direction I expected to be going in when I started the book. But there it was. It was money in the street; they were both willing to have me trail along [through their separation], and it's the part of the book that readers have really responded to.

What else caught you off guard during the interviews?

There were times when I wondered if I was seeing things I wasn't meant to be seeing. I think of being in Sylvia Miles's bathroom, or of overhearing Harold Bloom chastise one of his students over the telephone, or even a moment like going to buy the Chiquita banana costume with my mother. That was a moment when I thought, “I bet Joan Didion doesn't do this kind of research.”

What about interviews that were very moving for you?

Speaking to the woman who lost her house and husband in Hurricane Katrina made me weep. There's one page of the book that I literally cannot read without sobbing, a part about my mother and stepfather. It's very humbling and, again, it's stuff where I wonder.... I think pathos only redoubles comedy. Often, good comedy has this element of either loss or longing. So I hope that it's at work in what I wrote.