A piano quartet is generally scored for piano and a trio of violin, viola and cello, and consists of four parts. Brahms wrote three of them, the first two in 1861 and his third much later, in 1975. That last one is also called the Werther Quartet, after Goethes Die Leiden des jungen Werthers. However, it can also be seen as a declaration of love to Clara Schumann, Brahms not so secret love interest, and the wife of Robert Schumann.
A superb recording of well performed beloved works. Brahms shows himself here as a master of simply beautiful melodies. The fun thing with chamber music is that if you know the way, you can find real beauties. Sometimes the more adventurous compositions are found in chamber music literature. It is as if the composers can afford to take a bit more risk with their audiences, because these were smaller works, generally performed within the confines of the better situated families. Upper middle class families bought instruments and taught their children to play. It seems like the nineteenth century was full of these small works.
It feels as if the pieces that were composed by the big names in music are also the more challenging to play. But in a time where there was no radio, this might have been the easiest way to musical entertainment.