Iron Maiden’s famed song “The Number of the Beast” from the album bearing the same name contains a number of interesting analytical tidbits. The aspect that is most often examined is the quirky phrase length of the opening riff, which is regularly interpreted as being in a 5/4 meter. Such a meter is certainly appropriate for a song about an encounter with Satan; a five-beat subdivision can be read as being symbolic of the five-pointed star (i.e. pentagram) that is the traditional sign of the Devil.
It is also interesting to note that the initial riff, and much of the song, is in a major key (D major). There are no shortage of songs about Satan, demons, and other forms of evil in metal music, and usually those songs express “evil” in the traditional fashion: minor tonalities heavy on lowered strings, tritones, flatted seconds moving down to the tonic, etc. Yet in “Beast”, the major key, relatively high register, and tunefulness of the riffs invoke positive, almost happy energy. We often think of tritones and other dissonances as tools for making a song sound “evil”, but there is something truly deviant about the joyful and anthemic riffs that Iron Maiden use in “Beast”—the sound is celebratory, as if they really are singing Satan’s praise. Of course, any such effect is made with tongue in cheek, yet this presents a fantastic example of how the major key can be used in metal to create an ominous effect.
Finally, one of the most interesting aspects of the song is found in the chorus riff. The basic chords of the riff are as follows (rhythm is not notated accurately in respect of copyright):
The first chord moves to the second chord with a slight change: the index finger on moves from the 3rd fret of the 5th string down to the 2nd fret, while the finger on the 5th fret of the 4th string remains stationary. The notes of this second chord are B (the bottom note) and G (the top note). Because the B is the bottom note, one might be inclined to interpret the B as the root note of this chord, in which case the G would have to be interpreted as a minor 6 suspension to the B chord.
However, even though the root notes of chords most often occur as the bottom note, that isn’t always the case. In this case, the G is actually the root note of the chord, and the B is simply the major third of the chord. If the B fell above the G, we would have no problem recognizing the major third. The fact that the B occurs below the G does not change the relationship between the notes — the G is still the root and the B is still the third of the chord.
A chord in which the root does not appear as the bottom note is called an inversion. Whenever the third of the chord appears as the bottom note, the chord is described as being in first inversion. If the fifth of a chord appears as the bottom note, then the chord is described as being in second inversion.
Inversions are interesting because they affect the perceived stability of a chord. The quality of a chord in inversion remains the same — major chords remain major, minor remains minor, etc. — but they present a slightly different sound and don’t offer the same sense of finality as a chord with the root at the bottom. One reason for this is because inversions create an internal dissonance; in this case, the B below the G creates the internal dissonance of a minor 6. The chord itself is still consonant, but we still perceive the internal dissonance as upsetting the stability of the chord.
The relative instability of chord inversions are helpful for keeping harmonic progressions moving. Harmonic progressions thrive as long as instability is constantly introduced and allowed to resolve to stability. This can be achieved with chords in root position (provided that dissonant chords like diminish or 7th chords are used), but chord inversions offer a more subtle level of dissonance and allows for consonant major and minor chords (which are perfectly stable in root position) to contribute to the fabric of instability.
Consider what this riff would sound like if Iron Maiden used a G chord in root position (as below). The movement of the bottom notes between the first and second chords is now a somewhat shocking leap downward (from C to G) instead of an attractive half-step descent from C to B. Even if the B is used as the middle note of the second chord to capture the C-to-B voice leading, the prominence of the bottom note would obscure that effect. It would also obscure the internal dissonance of the B below the G, so all we would hear is a perfectly stable G chord that doesn’t have a strong momentum to move to the next chord.
It’s amazing what one minor movement of an index finger can do — kudos to Iron Maiden for using a chord inversion in such a simple yet powerful way. This is also a lesson to all of us metal musicians to keep chord inversions in mind for writing our own music, for as this example shows, chord inversions can be very easily executed while contributing greatly to a harmonic progression.