I'm trying to figure out the theory behind these three chords and why they work together. At first I thought it was a C major scale since it tends to want to go there. But there's flats in there so maybe it's in F since there's a B♭, but then where does the E♭ come from?

  1. C - G
  2. E♭ - B♭
  3. F - A - C

I think this could also be written like:

  1. C5 chord
  2. E♭5 chord
  3. F chord

progression here in Synthesia.


7 Answers 7


In addition to Tim's great answer, we can also conceptualize this as being in C Dorian.

The Dorian mode is a major scale with a lowered third and seventh. C Dorian would thus have E♭ and B♭.

I think this is especially important to point out because of the A♮ (not A♭!) shown in your link. Another way to conceptualize Dorian is as natural minor with a raised sixth, which would be this A♮.

Dorian is very common in popular music. The I–III–IV of this excerpt is a very common feature of Dorian, as is the emphasized whole step between scale-degrees 6 and 5 (A and G).

  • 2
    @EzLo For metrical reasons, I hear C as tonic instead of F. To me, the C chords are treated as points of rest, whereas the F chords sound to me like they're waiting to resolve back to C.
    – Richard
    Aug 28, 2018 at 10:06
  • I'd just like to add here that American Beauty is a great film, and part of its greatness is an especially sensitive and original soundtrack. Just sayin'. Aug 28, 2018 at 10:28
  • I just noticed that Scarborough Fair by Simon & Garfunkel is in Dorian too!
    – user34288
    Sep 15, 2018 at 17:47
  • It's a bit tricky, in that all through, it homes on C, but the last chord is F major - and it doesn't sound like it's the first half of a plagal cadence. It sounds back home!
    – Tim
    Apr 20, 2020 at 11:24

They just do! But for some theory behind, it's entirely possible to mix in a parallel key. So here, the Eb/Bb (certainly not D#/A#!!) is from C minor. And yes, it could be written as C5 Eb5 F5. There are those amongst us who would argue they're not 'chords', but that's for another post...

It could equally be in F, as those three chords also feature in that key.

That sequence was used a fair bit in the '60s - Knock on Wood comes straight to mind.I - bIII - IV. Or, thinking in F, I - bVII, You Really Got Me. (Although that's nearly in key G!!). Or On Broadway.

  • The F chord at the end has an A in the top, so it's a full on F major chord.
    – trlkly
    Aug 27, 2018 at 20:42

I think this could be in the key of C or F, both major or minor, depending on the melody and the rest of the chords, I could think in examples for all cases if needed. In the major case, Eb would be borrowed from the parallel minor key.

As already said, all notes fit in both C and F minor pentatonics, and power chords over pentatonic scales are an old trick I guess, can't go wrong.


To my ear, it actually just sound like it's in B-flat major, but completely avoids playing the tonic chord, aka B-flat major. Since it avoids the tonic, it creates this feeling of always floating, never being anchored, like the bag in the scene.

If this is correct, then the chords would be analyzed as ii IV V, repeating.

You can try this out for yourself: end the progression with a B-flat major chord, with the top note also being a B-flat. To me, it sounds like I finally found rest.

  • 3
    I don't think so since it wants to go back to C5.
    – user34288
    Aug 28, 2018 at 12:18
  • 1
    It sounds in C to me too. Part of the reason is all the pedal tones on C. No hint of Bb to my ears. Aug 28, 2018 at 13:52

The piece is modal and written in the key of C dorian. Dorian is perhaps the brightest of the minor modes, creating a thoughtful and dreamy feel to the music. The notes in C dorian are the same as Bb major, but in C Dorian, more importance is placed on C as the tonic as opposed to the Bb; we feel a grounding towards the C in this piece, hence why you felt that C major sort of fitted the profile. However, this piece is based off of the Dorian mode in C with flattened 3rd and 7th scale degrees. Hope this helps.


To me it doesn't sound like functional harmony, it sounds like pentatonic music with a weak key center in C. If it was functional harmony in the major-minor system, then we would expect at some point to get a V-i, and the V chord would have a B natural in it. That never happens. Since our ears are attuned to functional harmony, the lack of functional harmony makes it sound enigmatic. That works because the point of the scene is to get across something mysterious and ineffable.


If you're to stay within the confines of key of C, then Eb and Ab can be viewed as tritone subs: Eb for Am and Bb for Em

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