BBC News has published an article on the so-called Devil's Interval, a musical phenomenon suppressed by the Church in the Middle Ages.
On the surface there might appear to be no link between BLACK SABBATH, Wagner's "Gotterdammerung", "West Side Story" and the theme tune to the "Simpsons".
But all of them rely heavily on tritones, a musical interval that spans three whole tones, like the diminished fifth or augmented fourth. This interval, the gap between two notes played in succession or simultaneously, was branded Diabolus in Musica or the Devil's Interval by medieval musicians.
In the newly-released documentary "Metal: A Headbanger's Journey", bassist Alex Webster of death metal act CANNIBAL CORPSE pays tribute to the effect of the forbidden "Devil's note" on heavy metal.
And rock producer Bob Ezrin pronounces: "It apparently was the sound used to call up the beast. There is something very sexual about the tritone.
"In the Middle Ages when people were ignorant and scared, when they heard something like that and felt that reaction in their body they thought 'uh oh, here come the Devil'."
A more modern advocate of the tritone is BLACK SABBATH — the rock outfit led by Ozzy Osbourne — particularly in their signature song, "Black Sabbath", a milestone in the genesis of heavy metal.
But this link between heavy metal and musical conjuring of the Devil in the Middle Ages comes as a bit of a surprise to the band's guitarist, Tony Iommi.
"When I started writing SABBATH stuff it was just something that sounded right. I didn't think I was going to make it Devil music," Iommi says.
He says he was aiming for "something that sounded really evil and very doomy" but admits he may have been unconsciously influenced by other music and was certainly not aiming to summon the Devil.
"Beforehand [we were doing] jazzy blues. It certainly wasn't something I thought about — I didn't read music. I had no terms for anything
"I like all sorts of classical stuff — various sorts of music, jazz, blues, to classical played a big part in my writing."
Read the entire article at this location.