Mathematics of Layla
Bernard Chazelle explains “the technical part” of Eric Clapton’s classic “Layla.” Played here with an assist from Mark Knopfler, for those in need of a reminder.
The intro and chorus follow the progression of “All Along the Watchtower” (i-VII-VI-VII-i, ie here, Dm-C-Bb-C-Dm): one of the most common chord sequences in rock (0:27-1:10). The song is in Dm, but the verse begins on a C#m (1:10) ie, its antipode on the cycle of fifths. By rock standards that’s as wild as it gets. In country music, you’ll often hear a singer move up or down by a half-step for no particular reason, as though a boring tune becomes interesting just by virtue of raising its key. But Clapton knows what he’s doing. When he leaves the comfort of Dm for C#m he actually modulates to its relative major E. Just wait: you’ll see there’s method to the madness. Now when he hits the root E (1:17), you should soon be hearing a nice interrogative D (the Mixolydian quest for a change): you need it as a leading tone for the coming F#m (1:18). But Knopfler seems asleep and drops the ball, so the transition is not as compelling as it should be.
The idea then is to go through a perfect cadence twice (ii-V-I-IV, ie, F#m-B-E-A) — the kind of downwind sailing I was talking about earlier. The final A is then used as the dominant of the original key of Dm. It’s all tonally “correct.” If you’ve ever heard of the harmonic minor scale but always wondered what it was about: this is your perfect illustration. In theory, from A the reentry should be to D major, not minor. Of course, home is Dm so Clapton has no choice. The problem is that A has a C#, which is not in the scale of F (the notes of the keys of Dm are given by the scale of F), so hundreds of years ago people invented a new scale called Harmonic (common in Middle-Eastern music), which gives us a leading tone to the tonic, ie, C# -> D. Voila!
That really clarifies things, doesn’t it?
Yeah, I don’t understand it, either. So why bother posting? Because of Bernard’s point:
Why I care about such analyses: because it’s a myth to think those guys woke up one day, grabbed a guitar, and composed these tunes. They have in them, as we all do, hundreds of years of cumulative musical sensitivity that was “invented” (not discovered) by people who worked out the theory. That’s what makes western music different from all others. Since the 9th century, it’s been built as a written theoretical construction. The interplay between theory and practice is tighter than in any other art form. So to think of theory as what scholars did after the fact to understand music is naive. In the West, the theory always came first. Don’t forget that.
I think that’s right. But it doesn’t mean that, for example, Clapton or other guitar virtuosos necessarily understand and of this from a technical standpoint. But they clearly know it.
via Jim Henley’s secret blog