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There are seven notes in a major scale. Each one is given a Roman numeral: I, II, III, IV, V, VI, VII. In C major this
means I = C, II = Dm, III = Em, IV = F, V = G, VI = Am, and VII = B diminished. Notice the sequence of chords:
major, minor, minor, major, major, minor and diminished, the same for all major keys. Therefore we can write a
chord sequence purely in these Roman numerals: I VI IV V. Regardless of the major key in which we play this it
will always comprise a major chord followed by a minor and then two majors. Their relationship to each other is
constant whatever the key. Compare these examples:
IVIIVV
C Am F G
G Em C D
Eb Cm Ab Bb
B G#m E F#These can all be described as I VI IV V. The pitch changes (and perhaps the ease of playing on the guitar) but the
effect of the progression is the same in each case. The Roman numeral system is a very useful way of describing
chord progressions. Once you get familiar with using it and thinking with it, you will find it an invaluable shorthand
for understanding progressions.
In this book additional abbreviations sometimes add detail to the Roman numerals:
i first inversion (in C major, iIV = F with A bass; iVI = Am with C bass)ii second inversion (in C major, iiIV = F with C bass; iiVI = Am with E bass)m minor version of what would normally be a major chord. (In C major IVm = Fm
instead of F)maj major version of what would normally be a minor chord. (In C major IIImaj = E
instead of Em)b chord on the flattened note of the scale (bVII, bVI, bIII)7 indicates a dominant seventh if the chord is major; minor seventh if it is minor (in C
major, I7, IV7, V7, bVII7 = C7, F7, G7, Bb7; in C major, II7, III7, VI7 = Dm7, Em7,
Am7; in C major, IVm7 needs the ''m" because IV is normally major. This indicates
Fm7.)Not only does the Roman numeral system help you to understand keys and progressions, and to see how in different
keys they mirror one another, but also to grasp how a single chord can have a different harmonic function according
to which key it is in. There is a practical use, too. If you write out a chord sequence in Roman numerals, play it in a
chosen key and discover the melody is too high for you to sing, it's easy to move it to another key without writing
out all the chords again.
Which Chords Belong Together in Which Keys?
I devised this table to assist students to work out chord sequences from records. This can be time consuming and
frustrating if you don't use a little knowledge to cut down the seemingly endless possibilities. A vast number of
popular songs can