For Bach, as for Maurits Cornelis Escher, rules of form were a challenge to create pure beauty. Just as the graphic artist effortlessly turned birds into fish and etched waterfalls without end, Bach performed miracles within the most difficult musical genre, the fugue. Die Kunst der Fuge became one of Bach’s unique highlights, as well as his swan song: he died while writing the last fugue.

Bach wrote his magnum opus on fugue as an abstract work: Die Kunst der Fuge has no instrumentation designation. Cuarteto Casals took up the challenge, performed the work many times and recorded the full series of canons, single, double, triple, counter and mirror fugues. The members found their inspiration in their quartet’s namesake, Pablo Casals, who was the first cellist to show the world the beauty of Bach’s Suites for solo cello.