In the portrait sketched by Virgil Thomson and presented last night in the Terrace Theater, Pablo Picasso conceals a complex soul under a simple surface; he is a man of strong personality, emphatic in his tastes and self-expression, apparently temperamental but never really beyond self-control. At times, he may seem volatile -- but at the core, he is as solid as a rock.

Thomson's portrait may or may not be consciously modeled on Picasso's work; in any case, it resembles Picasso in its strong sense of line, its mastery of a variety of styles and the ease with which it shifts from one to another -- above all, perhaps, in its economy. There is nothing unnecessary in it, nothing that does not function. One might guess that it was dashed off in a hurry, at a single sitting, only because of its air of spontaneity -- a flavor that has remained fresh since it first saw the light of day in 1940.

There is one drastic difference between Thomson's art and Picasso's, to be sure. The American enfant terrible (an enfant still at 86) works in one of the few media that the Spanish genius never mastered -- sound. The portrait of Pablo Picasso, titled "Bugles and Birds," was sketched not on canvas or on paper but in the notes of a piano, played with seemingly effortless grace by Yvar Mikhashoff in the first program of this year's Kennedy Center American Composers Series.

The program included a dozen portraits in all, amid more than 20 compositions. Most of the pieces were brief, as they would have to be to fit such numbers in a single evening. At one point, in the middle of a series of piano portraits, the program presented four world premieres in less than 10 minutes -- surely a record of some kind. But if the evening's focus was on Thomson the miniaturist, the brief compositions were pungent and expertly formed in a virtuoso variety of styles.

At one stylistic extreme, there was the wild chromaticism of the 1926 Sonata da Chiesa for viola, clarinet, trumpet, French horn and trombone, which Thomson described in his introductory remarks as "still something of a shocker." "It makes funny noises -- or nasty ones, if you prefer," he said -- but, as performed by the Hartt Contemporary Players, it made noises both intriguing and bracingly astringent. It was archaic and churchly in the forms if not in the harmonies of its outer movements -- an opening Chorale and a concluding, glorious fugue -- but the spirit of the music seemed to be embodied most explicitly in its central movement, a tango.

Those who were not overjoyed by the harmonic clashes of a trumpet in D with a clarinet in E-flat could find consolation in the pure Victorian drawing-room melody of "The Courtship of the Yongly Bongly Bo," a soulful, bittersweet ballad of blighted romance with a text by Edward Lear. Or in the setting of "Susie Asado" (text by Gertrude Stein) in which the words, "Sweet, sweet, sweet" were repeated by soprano Jane Garzo with enough sweetness to give cavities to a regiment. Or "A Prayer to St. Catherine" (text by Kenneth Koch) and "Stabat Mater" (French text by Max Jacob) in which religious subjects were handled with a piety that seemed simpler than it actually was.

In Thomson's stated opinion, the most daring work on the program may have been the 1930 Sonata for Violin and Piano, which he described -- quite correctly -- as "neo-Romantic" and very daring for the time and musical climate in which it was produced. In this work more than any of the others, the composer's love of melody seems to have taken control and lured him into some excursions that were charmingly rhapsodic but seemed uncharacteristically aimless -- particularly in the first two movements, which lacked sufficient contrast in pace and mood. The effect was not helped by the occasionally imprecise intonation of violinist Thomas Halpin.

The most extended portrait on the program was the Piano Sonata No. 2 (1929), which the composer described as his own "Portrait of the Artist as a Young Man." "I did not know it at the time," he explained, "but some years later I began to wonder what it was about that little piece that I was so attached to -- and that's it." It is an attractive portrait -- warm, dreamy and rather romantic.

It was in miniature what the whole evening was on a larger scale, even without the opportunity to represent his "Four Saints in Three Acts," his soundtrack music, his Cello Concerto and other masterworks -- a charming profile of a composer whom Marta Istomin rightly called, in her introduction, "a national treasure."