Although the pianist Keith Jarrett is probably best known as a formidable jazz musician, he has regularly played classical music too, particularly that of J.S. Bach. In 1994, he recorded six keyboard sonatas by Bach’s son Carl Philipp Emanuel, and these have finally been issued. Jarrett’s attunement to C.P.E.’s often quirky, unpredictable idiom yields performances which are constantly stimulating and bristle with vitality. The tricksy right-hand flurries in Sonata No. 3’s final-movement “Vivace” have a crisp tactility, while the “Adagio” of Sonata No. 5 has a palpable sense of dignity. Overall, this is an album packed with finesse and insight and a valuable addition to the C.P.E. catalog.