The chord of evil

by Peter W McOwan and Paul Curzon, Queen Mary University of London

The 'Devil's Interval' or 'chord of evil' is used a lot by Heavy Metal bands: it's the reason Black Sabbath music sounds evil (despite their lyrics tending to be about love!) Why? Because it involves playing notes three tones apart that give an 'ugly' discordant sound. In Renaissance Europe it was supposedly a punishable offense to compose anything using it as people thought it summoned dark forces. Today you can hear it in the themes for movies like Back to the Future and Jurassic Park. Black Sabbath found the riff as a result of playing Holst's 'Mars: the bringer of War' on Bass guitar the day before they first included it in a song.