The music of JOHANNES BRAHMS can be quite resolutely systematic. It certainly has a conservative element, and an effusive 1853 article from Robert Schumann (who was at the edge of a complete break with reality) in the Neue Zeitschrift fur Musik seems to have reinforced Brahms’ conservative leanings, as he wrote in a letter of somewhat shocked thanks:
The public praise you have bestowed on me will have fastened general expectation so exceptionally upon my performances that I do not know how I shall be able to do some measure of justice to it. Above all it obliges me to take the greatest care in the selection of what is published… (Swafford, p. 88)
From this point on, Brahms, true to his word, was exceptionally careful to publish works which were finished as completely as possible. Many other works were burned.
The Cello Sonata Op. 38 is a particularly efficient and finished (‘tight’ — however lengthy) piece of work; it took Brahms some time to finish it. Much of what happens in the piece evolves from the opening two bars, and from the stretching of a minor 2nd in bar 2 to a minor 9th in bar 7 (ex. a). For demonstrating Brahms’ method and focus, it is worth noting the similarity of the germinal material of the second and third movements to that of the first (see ex. b). Both the second and third movements bear a close resemblance to the initial idea of the first movement: a triad moving upward toward a flatted 6th ‘ a pattern nicely jumbled in the middle movement. 
Incidentally, the fugue material of the last movement bears direct comparison both to the fugue material of the last movement of the Viola Quintet, Op. 88 (see Concert of September 23, 2004) and J.S. Bach’s ‘Art of Fugue’. The similarities between these fugue subjects only make it all the more clear that they are from very different pieces. In retrospect, it seems that, even from the beginning of the first movement, the cello sonata may have been based on Bach’s theme from the ‘Art of Fugue’, but that is another story.
Whether these relationships between movements are perceived as useful or meaningful probably varies from listener to listener. Whether they were even intentional is also questionable. Brahms himself had a gruff reaction to the critic Schubring (in fact a very insightful advocate), who had extensively analyzed Ein Deutsches Requiem:
I disagree that in the third movement the themes of the different sections have something in common…. If it is nevertheless so… I want no praise for it…. If I want to retain the same musical idea, then it should be clearly recognized in each transformation, augmentation, inversion. The other way around would be a trivial game and always a sign of the most impoverished imagination. (Swafford, p. 234)
Notwithstanding the grumpy tone, it is easy to sympathize with Brahms on this count. If not used for performance reasons (and especially once written down), thematic comparisons of this type, tempting though they are, can indicate a proximity between ideas that the sounds don’t properly own. In any case, one can count on the piece being thick with similarities and precise in its development – and to come by its meanings honestly, if not always intentionally.