The sound of thunder and rain.
A church bell tolls mournfully and the first note is struck: dirge like.
Another tone, an octave higher timed with the next peel of the bell.
The third note is the clincher though: a half tone lower than a perfect fifth.
The Devil’s note.
There’s something creepy and unsettling about the relationship between this note and all the others in the scale. It’s exactly half way between the tonic and the octave in the western scale.
In blues music it’s used as a passing note. A place to pass through on the way to other places. As such it gives the blues scale an easy legato, a smooth or sly grace. But no one dwells on it.
In 1970, however everything changed. Guitarist Tony Iommi altered the landscape forever.
By ending a phrase with the flattened fifth, Iommi created a tension, an unsettling yearning for resolution that never comes. The song is Black Sabbath by the group of the same name. Iommi and co had set out to create music which summoned up the sort of feelings which bring to mind horror films. Indeed even the band’s name comes from an old Boris Karloff flick.
The music was heavy. Loud distorted guitar, driving bass, thundering drums, and the iconic vocals of Ozzy Osborne took in themes of despair, drugs, war and the supernatural.
Heavy metal had been born.