The six Bach Suites are mainstays of the literature for unaccompanied cello. Yo-Yo Ma recorded them as a young aspiring artist in his twenties, again in his forties, and now -- for what he says is the final time -- as a mature interpreter who is arguably the pre-emminent cellist of our time. We'll listen to what Ma has to say about Bach, and then we'll take a look at some of the other projects that he has delved into of late -- projects that have not been without controversy.