Dear Mr. Chappell:

Why are there three different kinds of minor scales—natural, harmonic, and melodic? It seems like such a tangled-up mess.

— Tangled

Dear Tangled:

The ultimate rule in music is to do what sounds good. Anything after that is driven by that principle. It also brings individual taste into the equation.

Regarding the three forms of minor, we must ask why they exist.

NATURAL minor is the NATURAL (unaltered, automatically-occurring) result of perpetuating the key signature. That leaves a whole step between its seventh note (in C minor, for example, Bb) and the next higher note which would be tone number one again (in this example, C).

HARMONIC minor exists because of HARMONY. Those mid-millennium Europeans were enjoying so much the tension and pull of the half step from (in C major for example) B natural in chord number 5 (G major) when it was leading to the C root note of chord number 1 (C major) that they wanted the same exquisite experience to happen when going from chord 5 to chord 1 in minor as well. Hence, they raised that seventh note from Bb to B natural in favor of this HARMONIC progression. Ever since then, chord number 5 has proceeded to minor chord number 1 with that raised tone, with only a barely noticeable tiny number of exceptions.

MELODIC minor exists because of MELODY. Then somebody noticed that there was an awkward gap of an augmented second in the harmonic minor scale between its sixth and seventh tones (Ab to B natural in this case). The remedy was to raise also the sixth tone to eliminate this gap. Easier to play, sing, and hear, melodically speaking.

Under these conditions, you have three sets of choices to make regarding notes numbers six and seven in a minor scale. I’m sorry, but I wasn’t there to put a stop to it.

— JC