Johann Sebastian Bach did for the cello what director Quentin Tarantino did for John Travolta: He took an object of derision, gave it something challenging and meaningful to do, and demonstrated what great potential it had all along. Like Travolta’s character in the 1994 film Pulp Fiction, Bach’s Six Suites for Unaccompanied Cello are readily appealing, even though to some extent they’re killers. Of course, some of the movements, especially those of the first suite, are easy enough to be among the first “serious” music given to cello students. But other segments pose real technical problems, and from the first suite to the last there are enough interpretive and expressive issues to occupy any cellist for a lifetime.

Yo-Yo Ma first recorded the suites 20 years ago and revisited them in 1998 on a set of “interpretations” used for a series of dance videos. Sony reissued that latter set a few months ago. But Ma says his current conception of the suites is rather different. “I think that priorities change at every stage of life,” he says. “As a person grows up, the way he or she interprets information changes. Bach has a unique way of coding infinite variety. At each stage in life you can make different specific choices of what to highlight in melodic, harmonic, and rhythmic structures.”

Says Jian Wang, whose Deutsche Grammophon recording of the suites was released in 2005, “I feel the way I play them is changing all the time. As a rule, I don’t like to have rigid concepts to perform a piece. When a player has a set concept or idea about how to play a piece, he or she is leading the music with the concepts and ideas. . . . Of course, I use concepts and ideas as tools to understand and learn a piece, but just as the scaffolds for buildings or molds for sculptures, they have to be discarded after their use.

“I always aim to be passive when playing, to let music lead me, as if I am hearing it for the first time. I listen and I feel touched; in the process I can find the most direct way to express what I am feeling. It’s a bit like the flow of a river. Water will always follow the most natural path if you leave it alone. Rather than digging a canal and making the water come, I prefer to let the water follow its own logic.”

Until about a century ago, the river that is the Bach Solo Cello Suites had ceased to flow. Such music had fallen out of fashion. Pablo Casals revived them, after discovering a copy of Grützmacher’s edition in a Paris thrift shop and recording them between 1936 and 1939. The suites have since taken their rightful place in the repertory.

Bach had written them between 1717 and 1723 (scholars disagree on the exact dates), during one of the few periods in his career when he didn’t have to devote all his compositional time to liturgical music. The cello was coming into its own after decades of being denigrated as an instrument for continuo hacks; “real” musicians had preferred the viola da gamba. Possibly inspired by such fine cellists as Christian Bernhard Linigke and Christian Ferdinand Abel, Bach decided to find out what the cello could do.

He conducted his exploration in suite form, each work beginning with a prelude and proceeding with a series of stylized dances, most of them in the old style (allemande, courante, sarabande, gigue), but some more modern (minuet, bourée, gavotte). The last two suites pose special problems. The fifth uses scordatura, requiring the A string to be tuned down to G to make some of the chords easier to play. (Many cellists prefer to find other approaches, avoiding the intonation problems associated with retuning.) The sixth seems to have been written for a five-string cello, with an E string added above the A to accommodate the very high passages.