At key moments, evoking fragments of the external but unwritten world can be instrumental in anchoring a character or scene. In Mann's Doktor Faustus, a novel about a composer who sells his soul, music, not magic, is the medium in which the composer works. Mann's narrator, a childhood friend of the main character, is a writer. Yet through his point-of-view, we come to see how music can be expressed through words. Ekphrasis, the art of describing artistic works in words, plays a role in Mann's character revelations, his novel's theme, and the plot device of introducing the infernal into an otherwise sober work of German realism.
E.B. White's book the Trumpet of the Swan, one of my childhood favorites, describes a mute swan learning to play the trumpet to compensate for his disability. Like Doktor Faustus, music is the protagonist's mode of expression, and plays a key role in communicating his feelings. White uses songs that Sam, the main human character, knows from camp, and famous songs with which everyone--even today's children--should be familiar in much the same way Mann uses Beethoven and Schoenberg's works to illuminate the plot for his audience.
The issue for writers is how much to use. It could be argued that Mann's dazzling intellectual asides detract from his books, turning them into works of criticism as much as they are works of literature. Many struggling writers, myself included, deal routinely with the problem of spending too much time in a character's head. That time issue goes doubly when referencing other works, no matter how seminal or well-known. Hybrid writers are finding ways to balance the novelty of their form with the touchstones readers need to traverse the narrative. Reading these new works and these new ways will help give traditional forms tools to troubleshoot some of the most difficult writing quandaries.
The latest issue of the Writer's Chronicle features an article on forms. But it also features Jennifer Egan's Goon Squad, which is describes as more than a novel, more than a collection of short stories. Egan also toys with ekphrastic description and PowerPoint slides in her novel. It's a wonderful starting point for anyone who wants to see what cross-pollination of the creative variety can do.