Eminem. (Evan Agostini/Evan Agostini/Invision/AP)

Migos. (Jordan Strauss/Jordan Strauss/Invision/AP)

The year of mumble rap was rough on pedantic grumps who use the term "mumble rap" — a pejorative hurled at young artists who smudge their rhymes with melody.

But if these insurgent young wild-styles still perplex you, two new lightning bolts may have brightened your December skies. The first one struck YouTube on Thursday: a locomotive 10-minute freestyle by Black Thought of the Roots. The second hit the sales floor Friday: Eminem's new studio album, "Revival." And while these were two distinct chunks of music — Black Thought's deeds sounded herculean while Eminem's notepad seems to have exploded in the microwave — both were cheered as rebuttals to the mumble-jumble of Lil Uzi Vert, Playboi Carti, Migos and all of the other young voices currently pushing rap into alien turf.

It's important to remember that this generational clash is really just a clash of techniques — rappers of all ages are ultimately tasked with decorating time, and there are different ways to do it. Veterans such as Eminem and Black Thought tend to be meticulous, offering an orderly sequence of verbal events, a steady drip of rhymed conclusions, sometimes even a proper story with a beginning, middle and end. They give us tension and resolution — the very things that make novels, movies and serial television so essential in our imaginative lives.

But does reality ever unfold like that? In recent years, young rappers have been decorating time in more lifelike ways, letting their words go blurry and slack, hedging their verses with fat pockets of dead air. This makes their music feel chaotic, unpredictable, disordered. And it denies our yearning for resolution, which makes it feel a lot like life.

You can hear it in one of the year's most mesmerizing songs, "Magnolia" by Playboi Carti, an itchy club anthem jammed with stalled rhymes and clipped syllables. Carti doesn't offer lofty metaphors, or skywritten punchlines, or any kind of traditional narrative arc — but that doesn't stop every sound that materializes on his tongue from sounding electric, spontaneous and alive.

It's almost impossible to imagine an Eminem song working this way, especially for Eminem. "The rhyme has to be perfect, the delivery flawless," he asserts on his new album, lamenting the burden of his genius while boasting about the fastidiousness of his craft. But throughout "Revival," he sounds like a prisoner of his own erratic personas, attacking President Trump on one track, comparing himself to him on the next. More than ever, he sounds like a prisoner to his own style, contorting his lyrics to fit around weak puns instead of transposing his words into music.

Black Thought's viral freestyle — hosted by the legendary radio man Funkmaster Flex on New York's Hot 97 — feels both lighter and heavier. It has unrelenting momentum, vigorous internal rhyme, a muscular sense of swing, plus shout-outs to Rakim, Franz Kafka, Nikola Tesla and Clyde Drexler. The only moldy spot appears just shy of the four-minute mark, when the 46-year-old takes a quick swipe at the youngsters: "I can't explain what these lame kids is talkin' 'bout."

Maybe this was just a moment of take-all-comers braggadocio. But why does the work of those "lame kids" need explaining? Music is mysterious. Why are we so reluctant to be mystified by it?

As listeners, we don't have to be. And we don't have to pick sides, either. Try falling in love with Black Thought's dexterity and Playboi Carti's spontaneity, then see if your life doesn't feel wider, deeper and a little closer to the unknowable.