By Michael Walsh

One day in 1924, Aaron Copland was struggling across Manhattan, trying to reach Aeolian Hall. There Walter Damrosch, the leader of the New York Symphony, was rehearsing the fledgling composer's first symphony. The subway was delayed and the rehearsal had already begun when Copland raced from Times Square to the hall a couple of blocks away. "I was in such a hurry that instead of going around the block to the stage entrance, I yanked open the front door," Copland later recalled. "Suddenly, I got a blast of my own orchestrations! It was a moment I shall never forget. It sounded so glorious to me, so much grander than I could possibly have imagined."

When Copland died last week at 90, he had been largely inactive as a composer for two decades. But even in old age, he never lost an unabashed, even cocky, self-satisfaction in his formidable powers of invention. As late as 1983, he was still on the podium, conducting one of his most famous works, Appalachian Spring, with the same firm, animated gestures that, when translated into sound, characterized his scores.

Bright, open and spacious, Copland's works captured the sweep, sinew and soul of America. His titles alone tell the story: the exuberant ballet Billy the Kid, the contemplative tone poem Quiet City, the moving, symphonic Lincoln Portrait and, most simply and memorably, the noble orchestral anthem Fanfare for the Common Man, which was recapitulated to such dramatic effect in his Symphony No. 3. Jerome Kern's remark about the place of Irving Berlin in American music--that he was American music--is no less true of Copland in the concert realm.

Born in Brooklyn, N.Y., to immigrant East European Jews, Copland came of age in Paris. He was the first, and most illustrious, of the expatriate composers to emerge from the atelier of Nadia Boulanger, the most influential composition teacher of the century. He was 20 when he met her, 23 when he returned home; but in those three years, Copland learned everything. For all its distinctively American sources and styles, his music was fundamentally an amalgam of influences traceable to the Paris years: the rhythmic drive and complexity of Igor Stravinsky coupled to the clean sonorities and bracing orchestration of Maurice Ravel.

Yet all it took was one chord, and the listener knew instantly that the composer had to be Copland. In the bite and grit of Rodeo, in the sturdy Shaker tune quoted in Appalachian Spring, even in the 12-tone experiments of Connotations, the sounds were unmistakably his.

Copland's importance extended beyond his purely compositional achievements. He was a brilliant spokesman for American music in books and lectures. Together with a remarkable generational cohort that included Howard Hanson, Roy Harris, Roger Sessions and Virgil Thomson, he established the validity of that apparent oxymoron, the serious American composer. He formed around him a tight circle of like-minded colleagues who dominated the conservative wing of American music, among them his close friend and protege, the late Leonard Bernstein, and David Diamond.

All of them produced music that is wholly, joyously American in style and feel, frankly melodic and laced with the tricky cross-rhythms that mark the master's scores. Yet Copland tirelessly encouraged young composers to find their own voice, in no matter what style. Difficult as the lot of the serious composer is even today, Copland made it immeasurably easier.

When asked his opinion of Copland's early symphony, Thomson said, "I wept when I heard it--because I had not written it myself." For more than six decades, many another American composer has felt the same way.