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The spookiest music relies on a little ditty monks used to sing about the apocalypse

Lithograph by F. Hasler after H. Hess, Wellcome Collection
What Death sounds like.
By Gwynn Guilford
Published Last updated This article is more than 2 years old.

Let’s face it. When it comes to creating a creepy Halloween atmosphere, the modern pop canon doesn’t have much to work with. Fortunately, ye olde Europeans liked their music a lot more chilling than “Thriller.” In fact, during the 19th century, it was composers like Franz Liszt and Richard Wagner who truly cracked the code of creepiness. The sonic dread they pioneered involved two key ingredients that horror movies and metal bands still use today: a forbidden sequence of notes known as “Satan in music,” and a spooky little ditty that Gregorian monks sang about the apocalypse.

Diabolus in musica

Back in the Middle Ages, most Western music was written in praise of God—and was therefore supposed to sound pleasant. For composers of the day, that wasn’t a huge constraint. Take a C major scale—i.e. just the white keys on the piano—plunk out any two-note combination, and you’ll find they’re all holy ghost-grade harmonies.

Except one.

Played in sequence or together, the notes F and B clash in a way that feels twitchy, unnatural, foreboding. (If you don’t have a keyboard handy, think of the first two notes of Jimi Hendrix’s “Purple Haze” or Metallica’s “Enter Sandman”—or American police sirens.)

It’s this interval that folks in the dark ages and the Renaissance called diablous in musica—literally, ”Satan in music.” Modern music theorists know it as the tritone (as well as a diminished fifth, or an augmented fourth), though it’s also called the devil’s interval or the devil’s triad.

“The reason it’s unsettling is that it’s ambiguous, unresolved,” Gerald Moshell, music professor at Trinity College in Connecticut, told NPR. “You don’t know where it’ll go, but it can’t stop where it is.”

To put it another way, if you change one of the two notes just slightly, the dissonance turns to harmony. What’s really happening when we hear dissonance has to do with the relationship between frequencies.

The two pitches of the devil’s interval create a much more complicated ratio of frequencies than other intervals—which makes them, therefore, much harder for the human ear to reconcile. (For instance, using our C major example, the frequency ratio of C to G is 3:2, while for the tritone, it’s 45:32, according to Classical FM.)

This demonic combo was taboo in medieval times, though there’s no historical evidence for the popular claim that it was banned outright. Indeed, the devil’s interval was still occasionally used—though, tellingly, only in the gravest of musical circumstances.

“In medieval theology you have to have some way of presenting the devil,” John Deathridge, professor of music at King’s College London, told the BBC in a 2006 article on the tritone. “Or if someone in the Roman Catholic Church wanted to portray the crucifixion, it is sometimes used there.”

The New York Public Library Digital Collections
Franz Liszt (at the piano) and Hector Berlioz (standing at left): two creepy music geniuses.

Even during the Baroque and Classical eras, as the Catholic Church’s influence over cultural customs faded, composers continued to eschew the devil’s interval. In the odd passages when the tritones appeared, their use was technical: to create—and quickly resolve—tension. Then suddenly, at the dawn of the Romantic era of classical music, there it is, in Act 2 of Beethoven’s 1805 opera Fidelio. As the scene opens in a dungeon, the kettle drums rumble menacingly—tuned in the devil’s interval. (They appear at around 1:20 in this recording.)

Something akin to obsession followed, as composers used tritones probed the darker corners of nature and humanity. Perhaps the best-known comes from “Danse macabre” by Camille Saint-Saëns, which we’ll explore more in a bit. Another Frenchman, Hector Berlioz, was so bold as to hit listeners with the devil’s interval in the opening of an aria (which, unsurprisingly, was about damnation). One of the more famous examples comes in the combination of two tritone intervals during Siegfried’s Funeral March in Götterdämmerung (“Twilight of the Gods”), the final opera of Wagner’s Ring Cycle. Franz Listz, a Hungarian composer and piano virtuoso, wielded tritones with ghastly gusto—for example, to evoke Dante’s descent into hell in the opening notes of his “Dante Sonata”:

The freaky rise of the Dies Irae

And at the same time as Romantic composers were reveling in the devil’s interval, they were also experimenting with another snippet of medieval Roman Catholic music used to evoke doom: the haunting theme from a 13th-century Gregorian chant called the Dies Irae, which is Latin for “Day of Wrath.”

When it’s just monk a-capella, the melody is plenty eerie. Romantic-era greats used it to conjure up music that is downright sinister.

Berlioz—the French creepmeister extraordinaire—gets credit for the blood-curdling breakthrough, when he invoked the Dies Irae in his 1830 work Symphonie Fantastique. Even without the apocalyptic refrain, the work is pretty freaky—essentially the story of a bad trip turned ghastly. It tells the story of an artist who, believing himself rejected by a woman he’s stalking, tries to overdose on opium. In the hallucination that results, he winds up killing the woman, being beheaded, and witnessing his funeral devolve into a witches’ sabbath. (You probably won’t be shocked to learn that Berlioz was a pretty accomplished stalker—or that some historians think he composed Symphonie Fantastique while high on opium. Oh, also, Berlioz once hatched a bumbling—and thankfully abortive—plan to murder his former fiancée.) The Dies Irae comes in during the final movement, in a fugue with the theme of dancing witches, a bubbling cauldron, and a diabolical orgy (in the recording below, at about 3:25).

The use of the theme spread from there, showing up in the works of Johannes Brahms, Charles Gounod, Pyotr Tchaikovsky, Frederic Chopin, and Sergei Rachmaninoff (who takes the cake for the most frequent use of the Dies Irae). However, Franz Liszt—who happened to be in the audience at Symphonie Fantastique‘s 1830s premiere—was the guy who really took the Dies Irae baton from Berlioz and ran with it.

The New York Public Library Digital Collections
Franz Liszt.

A pioneer of infernally tricky piano pieces, Liszt had a minor obsession with the devil, death, and other dark subject matters—and unsurprisingly, featured either the Dies Irae or tritones (or both) in a few pieces, including the aforementioned “Dante Sonata” and “Mephisto Waltz.” His “Totentanz” (“Dance of Death,” or in French, “Danse macabre”), a devilishly frenzied work for piano and orchestra, opens with the Dies Irae and includes the devil’s interval throughout.

The “Dance of Death” refers to a medieval allegory in which the dead rise to dance with the living to remind them of their mortality. The conceit was a popular subject of frescoes and cemetery murals across Europe—and as it happened, Liszt’s work was in part inspired by one such mural, Francesco Traini’s “Triumph of Death,” according to Emily Reese, a Classical Minnesota Public Radio host.

Etching attributed to J.-A. Chovin, Wellcome Collection
Dance of Death.

Danse macabre

The French pushed the “Dance of Death” beyond the confines of religious allegory and into the realm of celebration. By dressing as corpses at village fairs and court parties to act out this danse macabre (a custom that may have given rise to the Halloween tradition of costume-wearing). French superstition held that at the the stroke of midnight on All Hallow’s Eve—the forerunner of the modern Halloween—Death walks forth and summons the dead to follow him in dance.

Romantic era heavies like Gustav Mahler and Modest Mussorgsky depicted the “Dance of Death” in their music. But given France’s rich traditions, it should probably come as no surprise that the most enduring rendition—and, indeed, the biggest Halloween hit from the Romantic era—came from a Frenchman: Camille Saint-Saëns. And as with Liszt’s ”Totentanz,” Saint-Saëns 1872 tone poem “Danse macabre” exploits the doom-laden double-whammy of tritones and the Dies Irae.

The piece begins with 12 plucks of a harp string depicting the tolling of midnight. Then in comes the devil’s interval—raw, savage slashes of discord played on a solo violin that signifies Death (it’s sometimes described as Death playing the violin—the orchestral instrument most commonly associated with the devil). As MPR’s Reese explains about Saint-Saëns’ use of the tritone here, “it’s particularly unsettling because it doesn’t resolve to anything initially.” As for the Dies Irae, the theme appears about halfway through the piece; Saint-Saëns’s eerie major-key rendering makes the motif sound less foreboding than grotesque. Other innovations of aural horror abound—e.g. the xylophone is used to emulate the cracking of bones. When the oboe sounds the crowing of the rooster, the dead retreat, and the whole ghoulish thing ends.

Whether in a Jameson’s whiskey ad or in the creepiest-ever episode of Buffy the Vampire Slayeryou’ve almost certainly heard “Danse macabre” before. And the Dies Irae? It’s also ubiquitous as a go-to terror trope. For instance, so obsessed with the melody was Stanley Kubrick that he supposedly demanded that its use for the opening music of The Shining. It also figures into horror classics like The Exorcist and Poltergeist.

Meanwhile, among heavy metal bands, the devil’s interval has long enjoyed something approaching cult status. Slayer, for instance, named its 1998 album Diabolus in Musica. Perhaps the most famous paean to its unholy eeriness is the opening of Black Sabbath’s “Black Sabbath.”

While metalheads have carried on the Romantic Era–composers’ innovation of using the tritone to disturb, other genres have broadened its appeal. In the first notes of the song “Maria,” from West Side Story, composer Leonard Bernstein used a tritone to create a weird tension that then resolves—as did Danny Elfman in the opening notes of the theme from The SimpsonsThanks to the tritone’s unique ambiguity, it’s ubiquitous in jazz chords. Its wider popularity these days probably has something to do with the fact that Death and the devil have lost the power to terrify that they had 150 years ago. Fortunately, though, in the music written to explore those fears, that power endures.

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