They differ in one essential: He feels, as a principle, that no animal should be sacrificed for any reason, that we don’t have the right to make that determination. She, as a scientist, feels the same way but also understands that in such an ecosystem as these islands, there are indigenous species found nowhere else in the world and that the invasive species brought there by humankind should be sacrificed in order to keep these others from going into extinction. That is the moral dilemma at the heart of this book.

You’re very generous as you write about these two opposing characters, considering things from their perspectives. Did you surprise yourself with anything that you found yourself thinking? This is why I write fiction and only fiction. Everything that I do is an exploration. I’m looking to find the story, its themes, what it means. I don’t know when I start; it’s not programmed beforehand; it’s not an abstraction; it’s not outlined. I work organically, and I feel my way day by day, month by month, until I see it come together.

Alma and Dave certainly have their share of hard line positions. You’ve written a lot about the dangers of fundamentalism, haven’t you? Yes, I have. Dave even says, [paraphrasing] “You never give up, you never crap out, and above all, you never admit that you’re wrong.” Alma pretty much feels the same way. They’ve taken their positions, and there’s no in-between. This is why I love The Tortilla Curtain, about illegal immigration in Southern California.