Bach’s music has long fascinated jazz musicians, and Keith Jarrett has gone further than most in exploring the keyboard works. For Book 1, he plays a piano (for Book 2, he chose a harpsichord) and proves a respectful champion of this great score, offering a straightforward approach that is totally convincing. Not overtly pianistic, he presents the music with clarity, an evident feel for its structure, and a sensitive choice of tempos.