Even as orchestras, performers, enthusiasts, and critics across the nation--and across the globe--celebrate the one-hundredth anniversary of his birth, George Gershwin (1898-1937) remains one of America's most popular yet least appreciated composers. True, he is loved and revered for his wonderful popular songs, a few instrumental works, and the majestic opera Porgy and Bess. But most of his music is virtually unknown; hundreds of compositions, Broadway...