Keith Jarrett may be rightly known as a masterful improviser at the piano, but on Hymns/Spheres, he breaks form on an 18th-century Baroque organ at Germany’s Ottobeuren Abbey. Recorded one year after his historic concert at Köln, this double album presents yet another facet of Jarrett’s jeweled talent. By experimenting with the instrument in question, altering air flow through novel stop configurations, his in-the-moment expectorations touch the heavens even as they scrape their knuckles along the ground. In another’s hands, this dichotomy might ring false; in his, it approaches the sacred.