I’m pretty sure this was a subtweet, directed at someone who was going to try something new that I didn’t think would stick. And clearly this person I was talking to had to know about jazz to have a chance of getting this tweet, so I’m pretty sure I know who that person was. But that’s not important now.
The tweet is in reference to a song from Miles’ album Kind of Blue called “So What.” This was a pretty important song in the development of jazz, because it established the thing called “modal jazz.” Let me explain that.
You may recall that a very common chord progression is the 2-5-1. That starts on a 2: meaning that you play a major scale but start and end on the second note. For example, the 2 of a C-major scale would be DEFGABCD. As I explained in that other post, this is called a minor-dominant-7 because you have to flat the third note of a D scale (making it minor) and the seventh note (making it dominant-7). But it has another name, and that is the “Dorian Mode.” Dorian meaning second. Because it’s the two. Are you writing this down?
The song “So What” has the chord progression: 2. That’s it. Just 2. 2 2 2 2 2 2.
That was the innovative part. They decided that instead of moving around 2-5-1 or 1-4-5 or whatever, they’d just hang around on 2. It wasn’t truly innovative, since it had been done before. But Miles’ band took it to an extreme.
Playing just one chord for a whole song is a little dull. So after a while, they moved up a half step. This is not a change in the chord progression. It’s a key change. So this new part is still just 2 2 2 2 2…
And then after that, they go back to the original key. And more 2.
Playing a whole song in a single mode (in this case Dorian) is what we call Modal Jazz. And this is the canonical example of that.
So, without further ado, here’s Miles. You can easily hear the key change during the melody (we call that “the head”) when the horns are playing.