Garth Risk Hallberg, of The Millions Blog, tries to answer the question in More Intelligent Life.
In his treatise on drama, “Three Uses of the Knife“, David Mamet cribs a distinction from Stanislavsky. Some narratives, he suggests, leave us saying, “What a masterpiece! Let’s get a cup of coffee,” while others ask us to wrestle with them for the rest of our lives. It’s a contrast that feels almost obsolete in book publishing. On the supply side, publishers rush to promote “instant classics” before posterity can render a verdict. On the demand side, we feel grateful for the distraction of “a good read.” An academic cottage industry has arisen to debunk categories of high and low, obscuring tensions between inspiration and craft, between edification and mere delight. Still, the old Horatian binaries tend to obsess the serious novelist, whose medium lives and dies along the borderline where art and entertainment meet.