In 1822 Schubert abandoned his most famous and beloved work, the Unfinished Symphony, having completed only two movements, though he did sketches for a third. That same year he was diagnosed with syphilis, which would take his life just six years later, when he was 31. The symphony, which he never heard performed, is among the best in the orchestral repertory, maintaining a powerful tension between stunningly beautiful lyricism and overwhelming longing and despair. In the opening bars barely audible bass strings play a haunting, almost impossibly slow melodic line. As it resolves, the violins begin a pulsating whisper of a melody that becomes the accompaniment for the oboe and clarinet as they play the first statement of the principal theme. The second theme, in major, is among Schubert's best known. The second movement is gentler in its opening than the first--warmed by horns and a tender clarinet solo, the melody of which is picked up by the other winds--then returns to the searing intensity that fills this work. The CSO will also play Schubert's Ninth Symphony, a large-scale, four-movement work with many of the qualities of the Unfinished. It's broodingly somber and profoundly tragic, though on a much broader scale and with more repetitions, and it owes a great debt to Beethoven even as it foreshadows the works of later 19th-century German composers. This music is close to the heart of conductor Daniel Barenboim, who begins his spring residency with this concert. It's also the last Schubert he'll conduct during his final season with the CSO. Tue 2/14, 7:30 PM, Orchestra Hall, Symphony Center, 220 S. Michigan, 312-294-3000 or 800-223-7114, $15-$104.