His contemporaries knew Pierre Boulez as a man of strong convictions with a sharp tongue. As a young composer, he once told the musicologist Heinrich Strobel that the only thing he had in common with Mozart were the letters O and Z in his last name—yet in his later years, he included a number of Mozart’s works in his repertoire as a conductor, among them the B-major Wind Serenade known as “Gran Partita.” Daniel Barenboim and the Boulez Ensemble juxtapose this landmark score with Boulez’s own sur Incises, an intensely emotional large-scale work for three pianos, three harps, and three percussionists.