Library of Congress
The Fifth Brandenburg Concerto features flute, violin and harsichord as soloists. Such a trio was a common chamber music ensemble at the time, playing works for two melody lines and basso continuo known as trio sonatas. What is remarkable about this concerto is that the harpsichord functions as more than a supporting accompanist; it contributes whirlwind solo passages, and it issues a monster of a cadenza at the end of the first movement. This use of the harpsichord as a solo instrument foreshadows the seminal keyboard concertos Bach later assembled in Leipzig.
The middle movement, labeled “Affettuoso” (“with feeling”), presents the soloists without the accompanying strings. Unlike a trio sonata, in which the harpsichord would typically have just a bass line with the right-hand harmonies filled in ad libitum, the harpsichordist’s right hand has its own melodic line that intermingles with the flute and violin. In the finale, a fugal structure reinforces the equal footing of the voices. The violin and flute take the first two entrances, and the harpsichord jumps in with the third and fourth voices of the fugue.