The string quintet was the last mainstream chamber music genre to which Brahms contributed.  An earlier abortive attempt to write a quintet with two cellos (the “Schubert” quintet ensemble) eventually led to the Piano Quintet, Op. 34.  When again embarking on a string quintet in the spring of 1882, he opted for the more common “Mozart” ensemble of two violins, two violas, and cello.  After straining his medium in the three string quartets, the quintet allowed him more freedom along the lines of the earlier sextets that preceded them.  The F-major quintet is a special work in many ways.  It is the only chamber work outside of the sonatas for solo instrument and piano that is in three movements instead of four.  The extremely complex structure of the second movement, which combines the functions of slow movement and scherzo, reaches back to the composer’s early years.  The movement uses as its source material two of a series of neo-baroque keyboard dances that he wrote in the 1850s but never published, specifically a sarabande and a gavotte, both in A major.  They are completely translated into the string idiom.  A similar structure on a smaller scale would later be used in the A-major Violin Sonata (Op. 100), a work that, like this one, has a brief finale.  The first movement is gloriously melodious and pastoral while presenting a tightly argued form.  The combination of fugue and sonata form used in the finale seems directly inspired by the finale of Beethoven’s third “Rasumovsky” Quartet (Op. 59, No. 3).  Another prominent feature of this satisfying but rarely performed work is the ubiquitous use of an unusual secondary key, A major, in all three movements.  The second themes of the outer movements are both in this key (not the expected “dominant,” but the “mediant” to F major), as well as the contrasting sections of the second movement.  That movement even ends in A major instead of its nominal “home” key of C-sharp (which vacillates between major and minor throughout the slower sections).  The finale is often criticized as being too brief to balance the other two movements, but Brahms tended steadily toward short finales in his later chamber music.