“What do we call visible light? We call it color. But the electromagnetic spectrum runs to zero in one direction and infinity in the other, so really, children, mathematically, all of light is invisible.” When people tell you to read a book, listen to them. I’ve been getting recommendations for this one for a while, but I put it off because it seemed like a depressing read. I like historical fiction, but the sound of this novel — set in a small coastal French town during its occupation by and liberation from the Nazis — did not excite me. It seemed dark and depressing. However, I could not have been…