But first Brahms got down to work, finishing his cello sonata. The first two movements had been written down a few years earlier, but the finale presented a problem. Brahms chose a rather thorny, academic solution. He turns back to Bach and writes a fugue, which is multiple counterpoint. This is tough on the performers, and sometimes it is even difficult for audiences. Mathematicians love it, however, because counterpoint is all about numbers. Just listen to that fugal subject played forwards, backwards, upside down, in different keys and different speeds. This recording was made in the Thirties and features two monumental giants of their respective instruments.