Though standard harmony textbooks don’t mention it, you can find “progressive tonality” on Wikipedia; I think it’s a misnomer, but the term is often heard in loose contexts, and there’s a basic definition that seems useful enough. “Progressive tonality” was apparently first described by Dika Newlin in her book, “Bruckner, Mahler, Schoenberg,” which arose out of her Ph.D. dissertation in the 1940s. (I knew Dika Newlin slightly from AMS meetings. She was distinctly an eccentric personality, if that’s the right description; but she was a good musician, a loyal follower and chronicler of Schoenberg, and her book, though dated, is still usefully readable today.)
Chopin’s F Major Ballade, with substantial sections oscillating between F major and A minor, and ultimately ending in A minor, is cited as an example; tonally speaking, it would seem to dislodge the idea of closure, i.e., that a piece of music should end in the same key in which it began. Yet most of us are open-minded enough not to regard Chopin’s different ending as a defect, one that we can actually hear.
Chopin’s Scherzo No. 2, Op. 31, offers “progressive tonality” of a different kind. The first phrase of the piece is all B-flat minor. The second phrase, mm. 9-22, is a paradigm of the problem that isn’t a problem. The upward four-note motto, recurring many times throughout the work, is clearly in B-flat minor. But bars 13-17 are D-flat major, the first appearance of that relative-major key in the work; its ff A flat in bar 13 descends from the corresponding Bflat in bar 5 of the previous phrase (not shown). The cadence on D flat in bar 7 is immediately contradicted by the dominant of B-flat minor (bars 18-22). B-flat minor and D flat major are constantly referenced back-and-forth throughout the entire Scherzo, with D-flat major eventually predominating and finally concluding triumphantly. This Scherzo has always been published as “in B-flat minor”, but Heinrich Schenker’s analysis in Der freie Satz specifically identifies it “in D-flat major.”
That there thus seems to be a dispute about the principal tonality tells you something about what it means for a piece of music to be “in” a particular key. Short pieces, such as any of Schubert’s sixteen-bar waltzes, are usually “in” a single key. A slightly longer piece, like the Minuet from Eine kleine Nachtmusik, can be “in” one key, be followed by a Trio section in another key, and in the Da capo return to the first key (in this instance, G major – D major – G major). Any greater length, and change of key surely becomes an aesthetic necessity, and there’s no limit to what can happen to the key then. (Take a look at Beethoven’s Two Preludes, op. 39, for piano or organ, “through all the major keys.” At one point you find the key signature changing in every bar, all the way around the circle of fifths, twice. The “or organ” takes on a significance, if you consider these pieces to be used in church, to get from one key to another. But both these curious pieces are considered “in C major”, as a whole. Then think of a much larger work, such as Meistersinger or Falstaff, each opera beginning and ending in C major, with umpteen other keys in between beginning and end, and ask what it means to say that one or the other might be “in C major.”)
A particular key is established for a certain time by the way the music defines it. This normally requires a cadence from dominant to tonic — establishment, and confirmation, made stronger by the presence of the tonic note in the upper part of the tonic triad, by rhythmic strength, by repetition, and by other factors, and of which can be dislodged, diverted, or dissimulated — but that’s what music is supposed to do.
In Chopin’s Scherzo the tonal strength is bifocal — B-flat minor at one moment and D-flat major the next, constantly shifting not just back and forth but modulating to a multitude of other keys as well. In the opening section (mm. 1-132) and its slightly varied repetition (133-264), the initiating Bflat minor motto is repeated eight times, but D-flat major prevails overall. The Trio section that follows (Sostenuto, mm. 265-365) likewise has a repetition (366-467); this is in A major, modulating to E major (leggiero), but with substantial emphasis on C-sharp minor in between, especially gravitating melodically to the C sharp pitch itself. Some of that gravitation is even stressed in the notation, to make sure that the pianist doesn’t miss the point. (285)
Following the repeated Trio section, Chopin decides to include a Development of the Trio themes, a wild ride through successive keys, including chromatic sequences, eventually arriving back at B-flat minor (sempre con fuoco, m. 544). This goes on all the way to m. 583, with plenty of dominant of B-flat minor — a counterbalance, in timing, to the D-flat major of the opening sections. The da capo begins at mm. 584-8, sotto voce, corresponding to mm. 1-5, and so on to m. 716, where the Coda begins with a sudden, painful interruption in A major — the key that began the Trio section (we might have forgotten about it from long ago):
Mark DeVoto, musicologist and composer, is an expert in Alban Berg, also Ravel and Debussy. A graduate of Harvard College (1961) and Princeton (PhD, 1967), he has published extensively on these composers and many music subjects, most notably, harmony.