When Robert Spano made his debut as a BSO assistant conductor 15 years ago, he chose a work of Sibelius. And Sibelius, one of his favorite composers, is with him again this week -- the Third Symphony and the BSO's first performance of the tone poem ''The Bard," an unknown movement from a suite that contains two of the composer's most famous pieces, ''The Swan of Tuonela" and ''Finlandia."
''The Bard" is strange and haunting and gives new meaning to ''austere." The harp plays throughout, in broken, harmonically unpredictable chords; Ann Hobson Pilot was the commanding soloist. Even when Sibelius was writing non-programmatic music, as he was in the Third Symphony, the music still evokes forest murmurs, bits of folk song and dance, and landscapes both natural and psychological. Spano led a compelling performance, propulsive in rhythm, and marked by clarity and intensity -- although his intensity has mellowed a little, and every performance is not like electroshock therapy.
The evening's soloist was the Polish pianist Piotr Anderszewski, who played Beethoven's First Concerto. Dressed in a black silk suit with a gray silk T-shirt, Anderszewski gave an original yet unostentatious performance, intelligent, witty, sensitive to deep song, and marked by shafts of illumination. He wasn't finicky about pianistic detail and the performance sounded spontaneous, not practiced to death; it was dominated by his ear and imagination. He created pizzicatos of his own to match the strings at the close of the slow movement, and veered amusingly between the mechanical and the playful in the finale. Spano and the orchestra kept with him, which took some doing.
The contemporary work -- and Spano always brings one -- was ''Nymphea Reflections" by Kaija Saariaho. In 2001 the Finnish composer spun it off from a work she wrote for the Kronos Quartet and electronics 14 years earlier. The music is an ingenious and evocative exercise in sonorities, dynamics, and atmosphere, often beautiful, but at 20 minutes rather protracted. In the last section the players whisper a poem by Arseniy Tarkovsky, the refrain of which is ''But there has to be more." By that point, this listener was hoping for an aura of pink light and the onstage appearance of Miss Peggy Lee to sing ''Is That All There Is?"