"I want to thank you for greeting me so warmly," Aaron Copland said to the Terrace Theater audience last night before a concert of his music. He paused for a moment, as if remembering: "I wasn't always so lucky. Speaking as one who has been in the composing business for 50 years -- I don't believe it -- I can't say we've been spoiled, we American composers." Then, in introducing the program, Copland said, "I don't think that any of the pieces you are going to hear will cause you any serious misgivings."

The concert was the first of the five new series of Terrace Concerts, and the first of six programs that will present music by living American composers. It was an auspicious opening to another facet of the Kennedy Center's 10th anniversary celebration.

The music included Copland's violin and piano sonata, the piano solo, Night Thoughts, the Twelve Poems of Emily Dickinson, the Piano Variations and the Sextet for piano, clarinet, and string quartet. It was music drawn from more than 40 years in Copland's creative career, stretching from the Variations of 1930 to the Night Thoughts, written for the 1972 Cliburn Competition in Fort Worth.

The five works presented much of Copland's most characteristic thoughts, with the idiomatic rhythms, sometimes close to jazz, often flowing smoothly along, as they do in many of the Dickinson songs. The harmony, too, was that which has come to be thought of as Coplandesque, with its mixture of white notes and dissonances matched by frequent diatonics. There was Copland's way with melodies, as often emphasizing his personal way with sevenths and seconds as reminding listeners of his affection for stepwise progressions. And always those things that seem inevitable mingled easily with those that continue to sound unexpected.

The performers were all deeply in touch with the inner meanings of Copland's music. Pianist Ursula Oppens played in each of the works, making her stronger impression in the craggy Variations, where her power had its chief opportunity to speak out, and in which she displayed unusual feeling for the forward motion of the familiar music. She was a constant source of beauty for the entire program.

Paul Zukofsky was the violinist in the sonata, returning for the Sextet. A master of contemporary styles, he quickly uncovered the appealing heart of the sonata.

Night Thoughts has a subtitle, "A Homage to Ives." Copland said of it, "By calling it that, I stopped a lot of my friends from telling me how Ivesian it sounds." It is a singularly fragrant elicitation of thoughts shared by the two great American musicians.

The Dickinson poems inspired Copland to create some of the marvels of American song. To the extraordinary thoughts of the poetry, Copland gave music of intense, though predominantly quiet, beauty. Jane Bunnell sang with a fine feeling for the music. Her voice is a lustrous mezzo, but she has minor problems with indeterminate pitch in soft passages, and her enunciation varied from extreme clarity to mushy indistinctness.

Expert musicians joined Oppens and Zukofsky in the sextet: Nancy Elan, violin; Koichiro Harada, viola; Joel Krosnick, cello, and Stephen Hartman, clarinet. Hartman was especially effective in the rhapsodic episodes in the sextet's slow section.