Relative Major and minor scale/keys
One thing we do have to talk about briefly is Western music theory’s relative Major and natural minor key structure.
First, you need to know what parallel scales are. Parallel scales are all scales having the same starting note. So C Major and all variants of C minor are parallel scales, they all start on C.
The C Major scale (having no flats or sharps in it’s key signature) also provides for and actually embodies a minor scale (or key) employing no flats or sharps — A natural minor. That statement refers to relative Major and minor scales. The term relative is appropriate here. It means, like family or same genes.
The natural minor scale (some say) springs from and is simply a variant of the diatonic (Major) specie — hence the honor of being called pure or natural. If a two octave sample of the diatonic (or Major) scale is examined, you will find within it a group of eight consecutive tones displaying the pattern of intervals commonly called a natural minor scale. Precisely stated; the relative (and natural) minor scale begins on the sixth scale tone of any given Major scale and continues through one octave of the otherwise Major scale tones.
To illustrate the concept of relative Major and minor scales, we’ll identify the relative minor of C Major (Figure 1). A minor (natural) is the relative minor of C Major. Relative Major and minor scales contain exactly the same tones (same genes). Their difference is a matter of starting point. That is, on which tone they begin (given a multi-octave sample of a single repeating diatonic pattern).
Further illustration of relative scales being just different parts of the same whole can be seen by performing a similar but reverse operation. That is, by extracting a relative Major scale from a multi-octave sample of the natural minor scale (Figure 2).
Any relative Major scale begins on the third tone of its relative minor, and continues through one octave of otherwise natural minor scale tones. Given that relative Major and minor scales share the same tones, they exhibit the same number of (and particular) flats and sharps (if any) within their spellings. C Major, for example, has no flats or sharps. Neither (therefore) does its relative natural minor, A minor.
Another example, G Major (Figure 3), employs one sharp, F#. Its relative minor, E minor, also incorporates one sharp — the same sharp, F#.
In this way two scale types (one Major and one minor) and two musical keys (one Major and one minor) can and do share a single key signature in music’s staff notation. You have flat keys and sharp keys and each key signature encompasses both a Major and a natural minor scale. Figure 5 summarizes and spells all relative Major and minor scale/keys. The quantity of flats or sharps used in the scale/key is the same as that exhibited by it’s corresponding key signature on the staff. Figure 4 is very similar but shows just the Major scales.
Figure 6 illustrates how to locate the tonics of relative Major and minor scales on the guitar fretboard, that is by moving either up or down from where you are. Starting from the topic of a Major scale, move either:
up a Major 6th (9°)
down a minor 3rd (3°)
Remember that this pattern is movable up and down the fretboard and it can also be used on other string sets. You can move the pattern over one string (so it starts on your A string) with no change in shape at all. Other string sets will exhibit the pattern shifts discussed when we introduced the Five Degree Calculation Line. The Major 6th interval (9°) up from where you are changes slightly (one fret) on some string sets.