No composer has been more important in defining what has become the American classical music sound than Aaron Copland. The open energy and harmonic clarity which he brought to his symphonic works has been atmospherically emulated for decades, and Copland’s music continues to conjure up an idea of Americanism. Before he could bring forth any definitive fashions for American music, however, Copland worked hard to define his own voice. He spent the early twenties (which were his early twenties) working with Nadia Boulanger in Paris, and steeping himself in the vibrant Modernist culture. Shortly after he got there, he finished a fine and openly experimental Movement for String Quartet. It is no masterwork, to be sure; but it is no student work, either. Its searching qualities are precisely his. And its energy, however derived from Stravinsky and the other celebrated Paris-dwellers of the time, is something which he brought to full to fruition upon his return, in an idiom with which we are now all familiar.