This work can be thought of as an informal symphony in the usual four substantial movements, composed for a specially constituted small orchestra. Much of the time the instruments are divided into two sections that answer each other back and forth.* Besides strings, Bartók includes piano, harp, celesta (see page 17), timpani — very important — and other percussion. We do not learn this all at once, however. The celesta makes its first entrance with an exquisite effect halfway through the first movement. The piano, harp, and xylophone arrive only in the second.

Second Movement (Allegro) The music bubbles over with variety, an exhilarating rush of melodic fragments, striking rhythms, folk-dance fragments, and novel percussion sounds. It is all held together by sonata form.

A “preface” played by pizzicato (plucked) strings precedes theme 1:

The preface, theme 1, and the contrapuntal bridge passage are all energized by motive a. One thinks of the motivic single-mindedness of Beethoven’s Fifth Symphony (see page 209). Bartók’s motive works especially well in the timpani, which play a powerful role in this movement.

There is a full stop after the bridge, so self-conscious that one wonders if Bartók is making fun of sonata-form conventions. The second theme group contains at least three very short themes. Theme 3 has a folk-dance lilt about it:

Suddenly the piano enters with a theme containing odd note repetitions. Since the pianist has hardly played at all up to this point, this new theme feels more like a beginning than a conclusion. Still, it functions as a cadence theme; very soon the exposition ends with another exaggerated cadence.

The timpani introduce the development section. Motive b, played pizzicato, comes in for an extensive workout. After a moment the strings drop down into an accompaniment for an amazing passage for piano, snare drum, and xylophone, punching out syncopated notes. This must have been inspired by the riot-producing “Dance of the Adolescents” in Stravinsky’s The Rite of Spring (see page 317).

Next, pizzicato string scales in imitative polyphony weave endless new knots and tangles. The scales blend into another folklike tune, similar to theme 3, which is repeated very freely. Introduced by the timpani, a fugue starts up in the lowest register, preparing for the recapitulation. The fugue subject is derived from theme 1, with the meter askew.

And when the recapitulation comes, after much signaling from the timpani, and after an expectant slowdown, the meter is changed throughout. Theme 1 vacillates between duple and triple meter, and the second group tips the balance: themes 2 and 4 each return in swinging triple meter.

Theme 3 returns more freely. It takes the piano’s odd “cadence theme” to bring us back to the solid duple meter of the start. As a coda, Bartók stages a fast, intense dialogue on theme 1.