I wrote this explainer for my New School students; maybe you will find it useful too.
The white keys on the piano don’t just have to play C major. If you play the white keys over a droning or repeated A, you get a very different-sounding scale. It has a few different names: the A diatonic minor scale, the A natural minor scale, or A Aeolian mode. I prefer to call it natural minor.
But this is only one of several minor scales in widespread use. The minor-key world is more complicated than the major-key world. But that also makes for a lot of musical variety. Let’s dig in!
Since A natural minor and C major are comprised of the same notes in the same order, you would expect them to feel closely related, and indeed they do. The key of A minor is the relative minor key to C major, and the key of C major is the relative major key to A minor. It sounds musically logical when you move from A minor to C major and back. It’s especially fun to take the same melody and play it over the relative major and minor keys. Here’s “Mary Had a Little Lamb”, first in its customary major, and then in the relative minor.
Here’s Béla Bartók repeating the same melody in D minor and then F major:
Björk uses the relative major/relative minor idea for her two released versions of “All is Full of Love.” She wrote the tune in B-flat minor, and that’s the version that was released as a single.
However, for the album version, Björk used a minimalist remix by Howie B that sounds more like it’s in D-flat major.
As you play with the natural minor scale, you may notice that its minor-ness is weak. If you emphasize the third too much, everything will start sounding like the relative major. Western Europeans decided that minor keys would feel more legitimate if they had a leading tone, a note that’s a half-step below the tonic. In A natural minor, you make the leading tone by raising G to G-sharp. This gives you a scale called A harmonic minor.
When you build a chord on the fifth degree of A harmonic minor, you get E7, which resolves dramatically and satisfyingly to Am. In natural minor, building a chord on the fifth scale degree gives you Em7, which sounds perfectly fine, but which has no leading tone and doesn’t have that feeling of a dramatic crisis being resolved.
Harmonic minor makes nice dominant chords, but Europeans found that writing melodies with it is problematic because of the big jump between F and G-sharp. Supposedly, this interval was too hard for people to sing, but it’s more likely that the sound reminded them too much of Middle Eastern and Arabic music. Aaron Searle argues that Western Europeans avoided that augmented second because they resented the Ottoman Empire. They were not wrong to hear harmonic minor as sounding Middle Eastern. If you play the fifth mode of harmonic minor, you get a scale that is variously known as hijaz, Ahava Raba, Freygish mode, or Phrygian dominant. American Jews will know it best from “Hava Nagila.”
For melodies going up the scale to the tonic, Western Europeans smoothed out the leap from the flat sixth to the raised seventh by also raising the sixth. If you take A harmonic minor and raise F to F-sharp, you get the A melodic minor scale.
In canonical music, melodic minor is not a “real scale.” You are only “supposed” to use it for melodies that walk up from the fifth to the tonic. When descending from tonic, European composers tended to use natural minor. There are exceptions, though. Bach runs freely up and down melodic minor all over the Chaconne. You can see why the less adventurous composers of his era handled melodic with care, though. It’s an extremely weird scale! The top half of it sounds major, and it has two tritones in it! These surreal qualities intrigued jazz musicians like John Coltrane, who explored the scale extensively.
Compare the minor scales here.
The main thing to take away from this post is that the European canonical composers did not think of natural, harmonic and melodic minor as three different scales. They conceived of a single minor scale with variable sixth and seventh degrees. If six and seven are both flat, you get natural minor. If seven is raised, you get harmonic minor. And if both six and seven are raised, you get melodic minor. You may have noticed there’s one additional possibility that I haven’t discussed. What if you raise six but leave seven flat? Then you get yet another minor scale, called Dorian mode.
The canonical composers (including Bach) studiously avoided Dorian mode. It was a commonly used sound in medieval music, but by the Baroque era, it would have sounded too old-fashioned. However, jazz, rock and funk musicians re-embraced Dorian, to the point where I have heard it called “the key of James Brown.” Here’s a classic James Brown tune in D Dorian.
There are yet more minor scales! There’s Phrygian mode, and Locrian mode, and octatonic, and you could make a case for the blues scale too. This rich variety is what makes minor keys so much fun to explore.
Here’s a track I made that goes through the relative majors and minors in all twelve keys.
Thanks for this. As a less experienced guitarist with some knowledge of theory, this is very useful. I’ve been memorizing/playing the minor scales but it’s great to have some background knowledge of why they were constructed.
There are only three diminished chords for every key, or tonality, they are the ones you have called jazz, blues & classical Since I regard a dominant seven chord as the home key for many jazz pieces, so I would have this setup:
for jazz in G mixolydian There’s the home tonality G B D F
then a semitone below, the diminished chord G Bb Db E
and a semitone below that the diminished chord containing leading notes, Fsharp A C Eb
There are two full diminished chords, and the partial one B D F
G7 is the home tonality & eleven notes are available as scale notes or passing notes
The remaining note Ab or Gsharp does not appear, or if it does it is in only at a full climax or cadential chords, such as an E7 preceding an A chord (either major or minor)
And I think of the Lydian mode as a major chord/scale wearing comfortable slippers, and the mixolydian mode as a major chord/scale wearing steel-capped work boots! That’s how I avoid using those ye olde names for he modes more than I have to, though they are second nature to me now, even so, naming things is always a confusing concept
Thank you, this is all very clear and logical, particularly melodic & harmonic minor without too much fuss Being mostly self-taught, I have my own organization chart I count seven scales only —
two with six notes, the whole tone scale & the (other) augmented scale
four with seven notes : major, harmonic major, melodic minor, harmonic minor
one with eight notes : the obvious octotonic scale
none of these collections of pitch classes (as scales) contain three consecutive semitones, nor three consecutive blank spaces
Simple, seven, that’s it, no more — the rest are modes (and the be-bop scale, where an extra note is inserted between ..)
The natural minor is explained as relative to the major, and vice versa
Might be good idea to relate these to the pentatonic collection (might as well call it a scale, but I dont)
A minor and C major contain the 5 note pentatonic collections of G, C, and F
C melodic minor has A D G C F which is F pentatonic
Both the harmonic major and harmonic minor contain a diminished chord with four notes
The modes, dorian, phrygian, mixolydian etc deserve attention as themselves, they are modes not scales, ( I call the dorian a minor wearing their best shirt and the phrygian a minor with a hole in their shoe )
The blues scale is not a scale, it is a device of magic, old as africa, new as being in outer space, and needs to be passed down mythically as much as practically