Happy Augmented Sixth Day! (2016 ed.)

It's been awhile on the blog, but I couldn't let Augmented Sixth Day pass without a post. (OK, I did let it pass the last three years without a post, but here's the inaugural celebratory Aug 6th Day post from Aug 6th, 2012.) However, I don't have much time as we're also leaving soon this morning for the last weekend of concerts at the magical Greenwood Music Camp, where our oldest daughter has spent her last five summers walking around barefoot and playing chamber music. Tonight she'll play movements from quartets by Beethoven, Dvořák, and Debussy, but in typical Greenwood fashion, each of the two marathon chamber music concerts will end with Mendelssohn, the greatest youthful composer ever. The last piece on the second program, which will happen around 11pm, will be the first movement of Mendelssohn's Octet (written when the composer was 16!), which may be my very favorite thing ever, even if Daughter of MMmusing won't be playing that. (She gets to go next-to-last, though, leading this bit of transcendent middle-period Beethoven.)

Anyway, as I was trying to think of a favorite augmented sixth chord to feature, I suddenly remembered some magical Mendelssohn this same daughter's young string orchestra performed six years ago. I wrote about that music in this blog post, trying to explain all the reasons why a low-quality recording of kids too young to know better is THE definitive recording of the slow movement of this particular string symphony Mendelssohn wrote when he was 12(!).



I mentioned briefly in that post that THE most magical moment in this movement occurs in the transition to the recap. The music has meandered from C Major into the relatively distant key of A-flat Major and in a classic "treading water" motion, the second violins and viola are slowly arpeggiating in A-flat as if lost and wondering where to go. In the third measure below, the harmony changes to C Minor* over the same A-flat in the bass (creating an achingly lovely major seventh sonority) and then the G changes in bar 4 to an F-sharp, so that we have the classic augmented sixth interval between the bass (A-flat) and F-sharp, and in classic augmented sixth fashion, this German Sixth chord resolves outwardly by half-steps, with the A-flat heading down to G and the F-sharp leading up to G. G is the dominant in C Major, and suddenly we're back in C Major with the opening theme back in the right key, although beautifully poised above the expectant dominant G in bass rather than tonic C. It is all SO much more sublime than I've just made it sound.

[The audio excerpt begins about 5 seconds before the score excerpt above.]

And there you have it. I'd love to say more, but I've gotta pack the car!

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* This is really better understood not as a C Minor harmony, but as the A-flat in the second violins descending down chromatically to a G in bar 3 above and then to the magical F-sharp.