The energy that Mozart unleashes with only an octave is incredible. The first movement obsesses on a single motive that musicians humorously label “Answer the telephone!” The style is the dramaticsturm und drang sounds characteristic of the German Romantic movement, a style Mozart absorbed from some of Haydn’s music. In fact it is in G minor, the same key we associate with Mozart’s dramatic 25th and 40th symphonies. It was this style precisely that influenced the dramatic and heroic style we associate with Beethoven.
But how differently Mozart uses a single motto than Beethoven. Beethoven is primarily reductive. He reduces his material to a handful of notes—think of the four note motto of the fifth symphony itself that reduces to three notes, then two notes, and finally a single note in the development section. Mozart, on the other hand, uses a motto additively, as a springboard for variations and new ideas.
The “Answer the telephone” motto is actually a complex phrase group that includes the six note motto itself and an answering tail. The motto begins with all the instruments in octaves playing a forceful falling fourth and ends with an appoggiatura, or leaning tone, all in a memorable rhythm that is two long notes followed by four short ones: Long-Long-short-short-short-short. That already is a lot of information: the falling fourth, the appoggiatura, and the distinctive accelerating rhythm. But the tail is even more interesting. The piano answers the motto by performing an octave leap in a dramatic dotted or broken rhythm, and then plunges rapidly down a scale nearly two octaves lower to conclude with an appoggiatura that echoes the motto itself. The energy unleashed from those three things—the octave leap, the dotted rhythm, and the plunging scale—is extraordinary and essentially fuels the entire movement.
A new tune begins quietly in the ninth measure. Or is it new? The texture is certainly new. The cello holds a pedal tone and the viola weaves through an alberti bass accompaniment over which the violin seems to play a new melody. But the piano comments on the whole affair with a quiet echo of its earlier fury, an octave leap followed by a graceful descent. In case we were in doubt, the strings then take up this figure leaving no question we are in a variation of the opening of the piece.
The following transition section brings the motto to the surface as the harmony moves to the major mediant (Bb major), the typical secondary area for a minor key sonata. In fact, the “second theme” is none other than the same opening motto now played in this new key. It is seamlessly connected to the transition, so that we only know it is the “second theme” because of the harmonic change to major. This movement then is a monothematic sonata, another echo of a favorite technique of Haydn’s.
But where Haydn and Beethoven would continually burrow into a single theme, Mozart discovers variety. First, Mozart mirrors the first group with a second phrase that is similar to the new tune from the ninth measure. And again, the piano part clues us into the real source of this material, now quietly playing the motto itself instead of its tail.
Mozart is never at a loss for new melody. As if to apologize for dwelling on only one tune thus far, the closing section of this exposition has not one but three new tunes. The first of these is one of Mozart’s most unusual creations. Over an oom-pah bass, the piano plays a tune so rhythmically mangled off beat, that we lose a sense of the meter entirely. It’s as if all the energy unleashed previously has left the meter of the piece itself frayed! Yet the music sounds incredibly graceful and beautiful, despite its metrical ambiguity. It’s a short moment—only 8 measures—but it stands out as a gleaming jewel in this piano quartet. The strings follow this with a more conventional theme in an opera-buffa style. A third tune, a codetta, ends the exposition, with the piano quietly reminding us of the motto playing octave leaps and then a short series of appoggiaturas.
All that information is just in the exposition of the first movement of this piano quartet. It illustrates the complexity that is always beneath the charm and grace of Mozart’s music. The development section even ramps up this process. We directly hear the inspiration for Beethoven’s style. Mozart reverses direction in the scales. Now they ascend instead of descend, and rush upwards more than two octaves. In the exposition, the scales released energy from the octave leaps. Now they are energy creators themselves. The acceleration inherent in the opening motto is here fully unleashed.