Brahms' attitude toward the importance of the string quartet as the ultimate expression of the composer's craft can be understood when it is considered that he reputedly sketched and destroyed some 20 quartets before creating one worthy of publication. Also, when it is considered that Haydn produced 68, Mozart 23 and Beethoven 16 quartets, Brahms' three quartets stand as a testament to his own harsh standards. The publication of the Quartets, Op. 51, then, represented for Brahms a milestone in his career similar to the publication of his First Symphony: he had taken on the masters of the past and now deemed himself worthy of comparison.
These first two quartets were completed just before Brahms seriously embarked upon his almost exclusive engagement with orchestral works and as such represent not only a culmination of everything he had learned to this point, but as models for all that was to follow. Brahms' greatest accomplishment as a composer was his "developing variation" technique in which an entire work was generated from a single motive or group of motives. In the two quartets of Opus 51, Brahms' gives no clearer nor more pervasive an example of this technique.
This quartet is so pervaded by the motives of the first movement, that it can be considered cyclic (a multi-movement work that uses recurring passages or themes throughout). The close tonal relationships and integrated key structure of the four movements add to the overall coherence. In the opening Allegro, a bold and rising arpeggio over a throbbing accompaniment sets the epic tone for the movement. It is in the strictest sonata form, with each subsequent theme developing and expanding logically and methodically out of the last. The Romantic character of the Romanze (Poco Adagio) movement belies its complex and highly organized structure. Its themes are all derived from the opening motive of the first movement. Third is the Allegretto molto moderato e comodo. Un poco più animato. This is a scherzo and trio in regular form. The main theme of the Scherzo, in an unusual duple rather than triple meter, is derived not from the opening of the quartet, but from the middle section of the first theme. The Trio is in Brahms' Ländler style, imitating an Austrian peasant dance. In the energetic Finale (Allegro), Brahms brought together all the motives and structural elements of the quartet. In addition, he used a section of the first movement's main theme as a recurring motto to articulate the movement's large-scale form.
