Classy nonfiction writer Susan Orleans was raised in Cleveland. “I grew up in libraries…,” she writes in “The Library Book.” She drifted away from library usage but after a chance visit to the Los Angeles Public Library eight years ago, “the spell libraries cast on me was renewed,” and then she grew fascinated with the 1986 fire that burned or damaged more than a million books. Who caused it and why? The fire’s history proved fascinating, with a local actor-wannabe accused of arson, and “The Library Book” see Orleans digging into it all. But the fire, which provides the book’s narrative spine, is just the launching pad for a generous, contemplative paean to the world of public libraries. As a lifelong library tragic myself, I basked in the artfully constructed mix of reconstructed history and insightful reflection. The writing is elegant, the innards of the Library are vividly described, and one comes away with a renewed sense of how important the world’s libraries are.