Bach or Magdalena? Bach's authorship of his famous cello suites was under assault last week at a Bach symposium. It remains to be seen whether scholars agree with the assertion that some of the suites were written by Bach's second wife, Anna Magdalena. While scholars discuss it, the music goes on. Cellist Yo-Yo Ma plays three dances from the Suite No. 6 in the Salle Gaveau, Paris.