Tri-tones - "Devil's Interval"

For a period in the Middle Ages, the Christian Church banned tri-tones (the interval of three whole steps between notes) for sounding "demonic," thus earning the tri-tone recognition as the "devil's interval." It was thought to be inherently evil and therefore dangerous, similar to our reading regarding music as temptation towards the devil in some examples of hardlined Islam.

More modern music has heavily incorporated tri-tones, both with intentional demonic sound (Black Sabbath) and with music that has no intention to sound demonic (the first two notes of the Simpsons Theme, which resolves with a happy-sounding 5th).

On example of a song that uses tri-tones to create a slightly unsettling and mysterious feeling is David Bowie's "Station to Station" - a song more strange than dark and demonic, but one that demon started the effectiveness of the tri-tone nonetheless. The tangible example is the alternating piano notes that start the momentum of the song.