If Leonard Bernstein's death two months ago was unexpected, then Aaron Copland's wasn't. And it wasn't just their ages, 72 and 90 respectively. Somehow Copland always seemed more patriarchial and, in recent years, much more withdrawn from the scene.

"I just can't get used to seeing Lenny with white hair," he is supposed to have commented some years back at Tanglewood. None of us could. Even in death, he will always be the vibrant, pulsing figure we remember from the concert telecasts and, more importantly, the music.The white hair, by contrast, always looked good on Copland, befitting his status as the elder statesman of American music. And with few exceptions the music we remember him by has that same quality of wisdom, simplicity and union with America's heartland.

There is an irony to that. Because Copland, like George Gershwin before him, was not a product of America's heartland. Born within blocks of one another, and only two years apart, both were from Brooklyn, the offspring of East European-Jewish immigrants. Yet between them they defined American concert music for this century in a way that no one, not even Charles Ives, has done before or since.

At one point they even had the same teacher, Rubin Goldmark. But where Gershwin, with his Tin Pan Alley background, moved toward formal instruction in an effort to acquire increased "legitimacy," Copland moved beyond it, using his classical training to forge a distinctly American idiom, however much it might have been based on European models.

"I wept when I heard it," the composer-critic Virgil Thomson said of Copland's Organ Symphony, premiered in 1925, "because I had not written it myself." Similarly it was Copland, not Thomson, who first knocked on Nadia Boulanger's door in Paris that historic summer of 1921, becoming her first important American composition student. That was followed in the early '30s by study with Mexico's Carlos Chavez, a sojourn that, among other things, resulted in his first really popular piece, "El Salon Mexico."

Betweentimes Copland's music ranged from the jazz-influenced (the Piano Concerto of 1926) to the atonal (most prominently the Piano Variations of 1930). In "El Salon Mexico," however, he made use for the first time of authentic native materials, an approach he would soon adapt to the music of his homeland.

Thus his music for the ballet "Billy the Kid" (1938) incorporates American folk songs, at the same time coining a language that to this day stands as the quintessential orchestral representation of the American West. In short order came "An Outdoor Overture," the music for the movie "Our Town," "Rodeo" "Fanfare for the Common Man" and, most resoundingly in 1944, "Appalachian Spring," which earned him both the Pulitzer Prize and the New York Critics Circle Award.

These are arguably the great works of Copland's "populist" period, followed by the Third Symphony (which incorporates the "Fanfare") and the opera "The Tender Land." At the same time he continued to write pieces of complexity and comparative austerity - things like the Piano Sonata and Piano Fantasy - as well as a few that, like the Clarinet Concerto and the Dickinson Poems, stand somewhere in between. And finally he even flirted, somewhat belatedly, with the serialism that had captivated so many others in his youth, via the "Connotations for Orchestra," premiered in 1962 at the opening of Philharmonic Hall, and "Inscape," turned out five years later and arguably his last major opus.

"Do you realize there isn't one young composer here, there isn't one young musician who seems to be at all interested in this piece, a brand-new piece I've labored over?" Bernstein recalled Copland lamenting at one of "Inscape's" first performances. Was it that kind of discouragement that brought what seemed even at the time a premature end to one of this century's most distinguished composing careers?

Whatever the reason, for a while it gave us an increased exposure to Copland the conductor. He himself would have been among the first to admit his abilities in that department were limited (although I once heard him direct a more-than-respectable Adagietto from the Mahler Fifth Symphony in Chicago). But I have to say for me no one - no, not even Bernstein - caught the freshness and rhythmic profile of his music quite as effectively as Copland at his best.

Happily that can be heard on a number of his recordings. Near the top of my list would be Philips' CD reissue of the earlier of his two recordings of "Billy the Kid" and the Third Symphony, which despite its "No-Noise" processing retains some of the punch of the Everest originals. And maybe at the top would be his Boston Symphony "Appalachian Spring," on RCA, together with his CBS taping of the complete ballet, in its original chamber scoring.

Those may be supplemented by his CBS recording, with Benny Goodman, of the Clarinet Concerto, along with "Rodeo," the "Old American Songs," "El Salon Mexico," "The Red Pony" and "Our Town." Along the same lines, I would not mind seeing reissued his recordings, also for CBS, of "An Outdoor Overture," the Piano Concerto (as soloist, with Bernstein conducting), the choral piece "In the Beginning," and, most of all, his abridgement of "The Tender Land." And, while we're on the subject, videotapes exist of Copland conducting the entire opera as well as a choral version of the concert suite; they've just never been made available on home video.

For the rest, one must resort to interpreters other than the composer. I have not heard the new Virgin recording of "The Tender Land," but can heartily commend Marni Nixon's (on Reference or Varese Sarabande) of the Dickinson Poems, and an Elektra/Nonesuch release conveniently brings together the Piano Variations, the Piano Quartet and the Sextet for Clarinet, Piano and Strings (arranged from the "Short Symphony"). Also, I have not included Copland's own recording of the "Lincoln Portrait," on CBS, mainly because it involves a fair amount of duplication ("Appalachian Spring" and "Billy") but also because in some ways I actually prefer Maurice Abravanel's.

In connection with the last work, however, it is interesting to recall that, because of Copland's leftist political leanings in the '30s, it was banned from the Eisenhower inauguration in 1953. Copland himself had prepared the text, largely drawn from Lincoln's words, as well as the music, about as solidly American a concoction as it is possible to think of.

"You just have to wait for history to take its course," he later said of the snub. "Things like that die out very gradually . . . if you live long enough." As it happens, he did and they did. And although he was not granting interviews on his 90th birthday last Nov. 14, it was reported that at the party in his honor he downed a piece of apple pie, which he preferred to cake.

Again, you can't get much more American than that.