A concerto grosso is a concerto for a group of several solo instruments (rather than just a single one) and orchestra. In 1721 Johann Sebastian Bach sent a beautiful manuscript containing six of these works to the margrave of Brandenburg, a minor nobleman with a paper title — the duchy of Brandenburg had recently been merged into the kingdom of Prussia, Europe’s fastest-growing state. We do not know why this music was sent (if Bach was job-hunting, he was unsuccessful) or if it was ever performed in Brandenburg.

To impress the margrave, presumably, Bach sent pieces with six different combinations of instruments, combinations that in some cases were never used before or after. Taken as a group, the Brandenburg Concertos present an unsurpassed anthology of dazzling tone colors and imaginative treatments of the concerto contrast between soloists and orchestra.

Brandenburg Concerto No. 5 features as its solo group a flute, violin, and harpsichord. The orchestra is the basic Baroque string orchestra (see page 108). The harpsichordist of the solo group doubles as the player of the orchestra’s continuo chords, and the solo violin leads the orchestra during the ritornellos.

First Movement (Allegro) In ritornello form, the first movement of Brandenburg Concerto No. 5 opens with a loud, bright, solid-sounding orchestral ritornello. We have seen this music before, as an example of a typical Baroque melody — intricate, wide-ranging, and saturated with sequences (see page 109). The brackets show the three segments of the ritornello, a, b, and c, that recur in the movement:

Once the ritornello ends with a solid cadence, the three solo instruments enter with rapid imitative polyphony. They dominate the rest of the movement. They introduce new motives and new patterns of figuration, take over some motives from the ritornello, and toss all these musical ideas back and forth between them. Every so often, the orchestra breaks in again, always with clear fragments of the ritornello, in various keys. All this makes an effect very, very different from Vivaldi’s Violin Concerto in G and Spring concerto, not only because of the sheer length of the movement but also because of the richness of the counterpoint and the harmony.

During a particularly striking solo section in the minor mode (the first section printed in blue in Listening Chart 5), the soloists abandon their motivic style and play music with even richer harmonies and intriguing, special textures. After this, you may be able to hear that all the remaining solos are closely related to solos heard before the minor-mode section — all, that is, except the very last. Here (the second blue-printed section in the Listening Chart) the harpsichord gradually outpaces the violin and the flute, until finally it seizes the stage and plays a lengthy virtuoso passage, while the other instruments wait silently.

An improvised or improvisatory solo passage of this kind within a larger piece is called a cadenza. Cadenzas are a feature of concertos in all eras; the biggest cadenza always comes near the end of the first movement, as in Brandenburg Concerto No. 5.

In this cadenza, the harpsichord breaks out of the regular eighth-note rhythms that have dominated this long movement. Its swirling, unexpectedly powerful patterns prepare gradually but inexorably for the final entrance of the orchestra. This is an instance of Bach’s masterful ability to ratchet up harmonic tension and expectancy.

Finally the whole ritornello is played, exactly as at the beginning; after nine minutes of rich and complex music, we hear it again as a complete and solid entity, not in fragments.

Second Movement (Affettuoso) After the forceful first movement, a change is needed: something quieter, slower, and more emotional (affettuoso means just that, emotional). As often in concertos, this slow movement is in the minor mode, contrasting with the first and last, which are in the major.

Baroque composers had a simple way of reducing volume: They could omit many or even all of the orchestra instruments. So here Bach employs only the three solo instruments — flute, violin, and harpsichord — plus the orchestra cello playing the continuo bass.

Third Movement (Allegro) The full orchestra returns in the last movement, which, however, begins with a lengthy passage for the three soloists in imitative, or fugal style (see the next section of this chapter). The lively compound meter with its triple component — one two three four five six — provides a welcome contrast to the duple meter of the two earlier movements.