Where Ferrante’s guidance seems most apparent is in Costanzo’s attempt to make the depth and disorder of a character’s consciousness visible, a technique he and Ferrante both refer to as “acquiring density.” Density works by cutting against psychological realism, casting off deterministic explanations for why characters do what they do: a girl defies her father because of her nascent feminist sensibilities; a father beats his child because he believes women must be kept in their place. These interpretations may be true, but they are too abstract, too neat—they have little to do with how a reader experiences a character’s actions as real. “What decides the success of a character is often half a sentence, a noun, an adjective that jams the psychological machine like a wrench thrown into the works and produces an effect that is no longer that of a well-regulated device, but of flesh and blood, of genuine life, and therefore incoherent and unpredictable,” Ferrante writes to me. “It’s the moment when the psychological framework breaks and the character acquires density.”