This is not for lack of indication; Gershwin has tempo markings all over the place, amply garnished with ritardandi and accelerandi and rubati both explicit and implicit. Here's what you get on the first four pages alone:
Molto moderato (♩=80)... and so forth. Out of 30 pages (this is in my very old, beat-up edition of the solo piano version) I count 23 that carry at least one indicated alteration of tempo. But the only metronome marking you get is that very first one. (And that seems to have been a late addition—the original manuscript of Ferde Grofé's orchestration simply marks the beginning as "Slowly.") Rhapsody in Blue is a piece that asks for near-constant tempo fluctuations, but puts the parameters of those fluctuations almost entirely in the hands of the performer.
It's also a piece for which, thanks to recording technology, the acquiring of an extra-notational performance tradition has been more or less completely documented. Probably the most obvious alteration has been in the big Andantino melody, this one:
Gershwin's 1924 recording with the Paul Whiteman orchestra takes all of this at the same tempo (as does, a little more loosely, Gershwin's piano-roll rendition), which is what's indicated, and which sounds weird to our ears, because the more common practice now is to double-time the last six bars of that phrase. That's how Oscar Levant and Eugene Ormandy do it on their 1945 recording. It's how Bernstein did it. It's how just about everybody does it these days.
The thing is, in order to do that passage, and that section, without the double-time distortion, you have to hit a pretty precise mark, tempo-wise: it has to be fast enough that the last six bars don't bog down (the Gershwin/Whiteman recording does plod a bit) but not so fast that the first two bars are trivialized. If you can hit that mark (about ♩=120, I've come to think, maybe a shade faster, though 126 seems a little too fast), it's kind of a structural boon: you can take the next eight pages or so, all the way up through the following Agitato section, at essentially the same tempo. But then you're more locked in than if you slide into the Andantino with Romantic languor, and then rubato the heck out of those six-bar consequent phrases. The performance practice that's evolved, in other words, gives the performer more room to maneuver—and more room for error.
The question that I've been thinking about is: does such room to maneuver also make the performance more expressive? At about the same time I started wrestling with the varying speeds of Rhapsody in Blue, I read this review of a concert from this summer's Sick Puppy festivities, and was struck by this description of Karlheinz Stockhausen's Kontakte:
I tend toward agreement with one of my seatmates, who described the experience as highly engaging intellectually, but emotionally remote.I don't wish to take the reviewer to task—I adore Stockhausen's music, but I fully understand that it's not everyone's cup of tea. Still, I was intrigued by the phrase "emotionally remote," since, to me, anyway, Kontakte is, if anything, emotionally in your face pretty much all the way through. (Here's a recording to sample.) The emotions, though, are not those usually associated with musical expressiveness.
It might be useful to reference Robert Plutchik's classification of emotions, in particular the way he divides emotions into opposite pairs. Musical expression tends to be those pairs on Plutchik's N-S-E-W axes: joy and sadness, anger and fear—perusing this summation of recent research into emotional communication in musical performance, the bulk of empirical research has surrounded those types of emotions: happiness, sadness, anger, fear, and love. My emotional experience of Kontakte, though, falls mostly onto one of Plutchik's in-between axes: the tension between anticipation and surprise.
Here's a typical section of the score to Kontakte:
There's a bit of leeway in the performers' staves, but it's always in the context of those implacable numbers at the top of the score, the music's running time, broken down to tenth-of-a-second accuracy. It's both the source of Kontakte's emotional effect and the subversion of our accustomed perception of it. To do a Rhapsody-like indulgently-slow-then-double-time move is completely foreign to this context. Any momentary freedom on the part of the performers is immediately yanked back into Kontakte's grid by the necessity of synchronization with the electronic component. And that seems to conflict with what we've come to accept as communicating musical expressivity. The notion was concisely stated back in 1925 by psychologists Carl Seashore and Milton Metfessel:
This deviation from the exact is, on the whole, the medium for the creation of the beautiful—for the conveying of emotion. That is the secret of the plasticity of art. The exact is cold, restricted, and unemotional; and, however beautiful, in itself soon palls upon us.Obviously—given my enthusiasm for the exacting emotional world of Kontakte—I don't buy that. But for all the modernist effort to demonstrate they are, in fact, two different things, the conflation of expressivity and emotionality persists. The more expressive emotions are not false; but mere expressivity is not the end-all of emotional experience. And a sidelong glance into the worlds of politics or nationalism or fundamentalisms of various kinds offers no end of warning signs for exclusively associating emotion with expressiveness.
It's interesting that, after Rhapsody in Blue, Gershwin came around to the greater precision of metronome markings. The only one of his subsequent concert works that doesn't include them is An American in Paris, and the experience of hearing Walter Damrosch conduct it too slowly apparently converted Gershwin. The Second Rhapsody is diligent with metronome indications, as is the Cuban Overture, as is the Variations on "I Got Rhythm." And it's equally interesting that none of those works has ever attained the place in the repertoire of Rhapsody in Blue. It might just be a coincidence—or it might be a measure of the general equating of performer freedom with communicative effectiveness. My own heresy: as much as I love Rhapsody in Blue, I kind of think that the Second Rhapsody is a better piece of music. But, then again, I know that I'm at the margins of the mainstream of perceived musical emotion. I don't mind—I may not get swept off my feet quite as easily, but the payoff is a view of the world made just a little more lucid.
Cross-posted at The Faster Times.