It is no longer a secret that the nation of Finland boasts a rich, diverse and extraordinarily vital musical life, but conductor Osmo Vanska provided some fresh evidence last night at the Kennedy Center Concert Hall.

Vanska led the National Symphony Orchestra through his countryman Jean Sibelius's symphonic fantasy "Pohjola's Daughter," the local premiere of Kalevi Aho's Symphony No. 9 for Trombone and Orchestra and -- in the program's one bow to the familiar -- the Symphony No. 3 in F by Johannes Brahms.

The Sibelius was extraordinary and boasted some of the best playing I've ever heard from the NSO. This is a strange and wonderful piece, almost minimalist in the way it is constructed from small modules of sound that eventually coalesce into a statement of considerable grandeur. Still despite the climactic brass chorales, which rang out with bite and brilliance, there is an eerie quietude to most of this 15-minute meditation. Indeed, it is imbued throughout with dark, loamy mystery, heightened by the composer's extended passages for solo players in the lower registers, and, at the end, the music simply evaporates.

Sibelius was probably the least academic of the great 20th-century composers. It is impossible to codify what he does in "Pohjola's Daughter"; it seems to have no antecedents and, by its very nature, it can never have a sequel, for to imitate Sibelius is to miss his whole point. The harmonies in "Pohjola's Daughter" are hardly so daring as ones that were being written by, among others, Richard Strauss and Arnold Schoenberg in 1906, the year of its premiere. Still, today Strauss and Schoenberg sound very much of their own time, while this particular 97-year-old piece, with no radical innovations but a deeply personal sense of expression, sounds so absolutely new that it could have been written yesterday.

Aho, who was born in 1949, is one of the leading Finnish composers after Sibelius. His Symphony No. 9 is a curious and often very effective catchall that, through the composer's originality and skill, ultimately takes on its own distinct voice. It has a spectacularly virtuosic part for trombone that calls for the soloist (here the dazzling Christian Lindberg) to croak and croon in equal measure. Opening with dense, plush, urgent sonorities that called the film scores of Bernard Herrmann to mind, the symphony metamorphosed briskly and regularly, often harking back to the baroque concerto grosso, with some extended and stylishly tinkly writing for the harpsichord.

Here again, it was not Aho's harmonies or any outre instrumental textures that seized one's attention, but rather the way the composer's idiosyncratic take on familiar gestures blasted them clean and made them sound fresh and inspired. The last movement was the most determinedly modernist of the three -- complete with a long, honking cadenza that had Lindberg simultaneously singing and squalling through his trombone -- and, curiously enough, it was the one that sounded the most dated, a sort of glossary.

Vanska's way with Brahms will not be to everybody's taste -- his approach is brisk, straightforward, unusually classical in mien (the symphony seemed derived from Haydn rather than the more usual Beethoven) and a little on the cool side. I would have preferred a little more sentiment in the third movement -- the haunting, wind-swept "Poco allegretto" -- but much enjoyed the lightness and clarity Vanska brought to the opening movement, which is too often lost in elemental surges.

The program will be repeated tonight and tomorrow night at 8.

Osmo Vanska led the NSO in works by Sibelius, Aho and Brahms.