The Italian pianist Maurizio Pollini is an adventurous virtuoso, a connoisseur of the traditional repertoire with a taste for some of the most difficult modern compositions. He has recorded the complete sonatas of Beethoven as well as all of Schoenberg's music for piano, and he is famous for exploring classical and contemporary pieces in a single performance, bringing as much earnest lucidity to avant-garde masterpieces as to beloved monuments.
To begin, Pollini chose Chopin's Two Nocturnes (Op. 55). Both were played briskly, with hardly any of the conventional elasticity of tempo. Next was the Op. 23 Ballade, its recurring melody here so simple as to verge on ironic. Two more Nocturnes followed, the Op. 48 pair, and it was in the second of these, in F-sharp minor, that the pace was finally allowed to slacken, the bass settling into a steady, mesmerizing throb. By the finale of the first half, the Polonaise (Op. 44), Pollini was at his most intense, so focused that even an apparent medical emergency in the fourth row did not break his concentration.
This was relatively standard fare, but after the intermission the mood turned darker. Pollini strung together four of the strangest 19th-century compositions for solo piano. Played without interruption were Liszt's ''Nuages gris," ''Unstern," ''La lugubre gondola I," and ''Richard Wagner -- Venezia."
After a brief pause, the program culminated in the enormous Sonata in B minor, in which Liszt dissolves the traditional multimovement structure of the piano sonata into one expansive whole. The quiet moments were nearly subliminal, and the powerful rattle of the left-hand chords in the Allegro Energico were as incomprehensible and discomfiting as white noise.
The genius of Maurizio Pollini is in this blurring of pleasure and provocation. A beautiful sound is well within his capability, and so he can cultivate some ugliness, clipping rhythms and thumping the pedal to achieve some startling new sonorities.
Pollini returned to the stage to play one encore after another: Debussy's ''La Cathédrale Engloutie," Chopin's Nocturne in E-flat Major, Liszt's 10th Transcendental Étude, and Chopin's Étude No. 12 (Op. 10, the ''Revolutionary") and Berceuse.