Although the chronology of the six Brandenburg Concertos is unclear, the collection’s technical challenges suggest that Johann Sebastian Bach composed them during his time in Cöthen for Prince Leopold’s famously skilled ensemble. The descriptive title hints at a mundane reality of the composer’s life, however. While Bach had been happy in his post, the court’s location was remote—some referred to it mockingly as “Cow Cöthen.” The court was experiencing budget troubles, and school crowding was also an issue; a 1722 memo mentions a teacher shortage and class sizes exceeding 100. It was time for a new job, and the Brandenburg Concertos, dedicated in 1721 to Christian Ludwig, the Margrave of Brandenburg, probably served as Bach’s “resume.” As the composer expressed in the dedication,

As I had the honor of playing before your Royal Highness a few years ago, and as I observed that You took some pleasure in the small talent that heaven has given me for music, and in taking leave of your Royal Highness You honored me with a command to tend You some pieces of my composition, I now, according to your Royal Highness, take the liberty of presenting my very humble respect to your Royal Highness, with the present concertos, which I have written for several instruments, humbly praying You do not judge their imperfection by the severity of the fine and delicate taste that everyone knows You to have for music, but rather to consider benignly the profound respect and the very humble obedience to which they are meant to testify. For the rest, Monseigneur, I very humbly beg Your Royal Highness to have the goodness to continue Your good graces toward me, and to be convinced that I have nothing so much at heart as the wish to be employed in matters more worthy of You and Your service.

While the Brandenburg Concertos didn’t lead to a job, they secured a position among Bach’s most beloved works.

Written for three choirs of strings (violin, viola, cello) and continuo, the Brandenburg Concerto No. 3 explores in depth the surprising possibilities inherent in groups of similar-sounding instruments. One of the critical ingredients is uniform virtuosity; the nine string parts are essentially equal, and each player comes forward at least briefly as a soloist. Subtle variations in texture and tone color are also extremely important. Unlike the traditional concerto grosso, which uses a distinct group of soloists against the entire ensemble, the third Brandenburg provides a wealth of opportunities for contrast between solo, small group, and unison ensemble. The result is a veritable kaleidoscope of different tone colors. In the first movement, melodic material encapsulated in the first theme is carried forward on waves of propulsive forward motion. In the finale, the movement from high to low register and back again serves as one of the organizing principles. Comprised of only two chords, the intervening Adagio may have served as a platform for improvisation by one or more soloists.