Understanding the Circle of Fifths is a useful tool in navigating Western art music. It’s taught in every theory class, and I use it often in both teaching and performing. But until recently, I never considered its relationship to the modes, also taught in music theory classes.
It started when I got this Circle of Fifths poster from Amazon:
It’s a pretty good and informative poster, so I hung it on the wall next to my piano. I liked it so much I even bought a frame for it.
Then I saw that I had the Circle of Fifths drawn on my whiteboard, which also lives next to the piano, but with this poster I didn’t need that any longer, so I erased it and started filling in the space previously devoted to the Circle of Fifths by writing down the modes. But instead of thinking in terms of whole or half steps, or from scale degree to scale degree, I was thinking of them in terms of changes from the major scale (Ionian mode).
So, I wrote down Dorian and the changes, Phrygian and the changes, and then I erased what I had written down and wondered if there was a different way to think about modes and the progression of changes from the major scale. And voilà, the Circle of Fifths presented itself.
If you go up a fifth from C major, the Mixolydian mode is the white-key scale from G to G. Its difference from the major scale is a flatted 7th degree. Go up another fifth, and the white-key scale is the Dorian, from D to D. And the Dorian has a flatted 3rd and 7th degree, and the 3rd happens to be a fifth down from the 7th. Go up another fifth, to the Aeolian mode, and the white-key scale is from A to A, and of course the new flatted degree is a fifth down from the 3rd degree of the major scale, and so on.
Of course, the outlier is the Lydian mode, which is the white-key scale a fifth down from C, from F to F, with a raised fourth degree. I’m still figuring that relationship out!