Some years ago, I was awakened early one morning by a phone call from a friend. She had just broken up with a boyfriend she still loved and was desperate to justify her decision. “Can you believe it!” she shouted into the phone. “He hadn’t even heard of Pushkin!”

We’ve all been there. Or some of us have. Anyone who cares about books has at some point confronted the Pushkin problem: when a missed — or misguided — literary reference makes it chillingly clear that a romance is going nowhere fast. At least since Dante’s Paolo and Francesca fell in love over tales of Lancelot, literary taste has been a good shorthand for gauging compatibility. These days, thanks to social networking sites like