The Boise resident and author is profiled in this morning's New York Times, in which he says he thinks "it's dangerous" for him to wonder why his latest work has been such a commercial smash.
"The kinds of readers I'm writing for, I thought they would like it, but I didn't think that Aunt Judy would read it," Doerr told The Times, adding that his book includes trigonometric equations and is "really dense."
Carolyn Reidy, chief executive of Simon & Shuster, told The Times, "An awful lot of titles drop off the best-seller list after months, and it's a miracle if it lasts more than four months."
Doerr's best seller, a 2014 National Book Award finalist, was out of stock on Amazon in the run-up to Christmas, according to The Times,
"People are clamoring for it," said Mark LaFramboise, book buyer at the Washington, D.C. store where Obama bought his copy.
As for what's next, Doerr said he's "toying" with three ideas: a story that takes place during the siege of Constantinople in 1453; the construction of the Panama Canal; and a spaceship on its way to the only habitable planet other than Earth.
"You just try to water these things like plants," Doerr told The Times. "and see which one gets the most light and flourishes."