Malcolm Bilson resurrected the music of Wolfgang Amadeus Mozart Saturday night as Schwab Auditorium echoed with "authentic" 18th-century sounds.

Performing a concert of four sonatas and one fantasy on a fortepiano, Bilson gave the audience a feel for what the drawing rooms and salons of Vienna heard when Mozart himself performed.

The fortepiano -- a five-legged piano with one pedal that is operated by the knee rather than the foot --was the precursor to the modern-day piano. More delicate and less dramatic than the grand piano, the fortepiano recreates the sounds of Mozart's pieces as he composed them.

Opening with Sonata in G Major, K. 283, Bilson made the perky, light piece more impressive with his quick finger work, his perfect timing and his emphasis on the bass.

This piece, while well executed, was quickly eclipsed by Fantasy in C Minor, K. 475. and Sonata in C Minor, K. 457. Bilson, with an almost gentle stroke, easily played the flowing but starkly somber fantasy, leading without pause into the sonata.

Weaving the sonata's bright theme with the darkness of the bass to create the most dramatic piece of the concert, Bilson played with verve, leaning his whole body into the keyboard and then away as he felt the mood changes in the music. With wild scales that drew his hands up and down the keyboard, Bilson showed off his technique as he made the waltzing phrases come alive.

Throughout the performance, Bilson's body movements were almost inseparable from the interpretation of the music. Frowning with his eyes intent on the keyboard, his hands and body spoke the language of Mozart.

Bilson was called back to the stage for an encore performance of what he said was "the first movement of the last (sonata) I learned." Recognizable as Sonata in C Major, K. 545, the piece was accepted with laughter and excitement by the audience.

The audience -- probably more accustomed to the dramatic and booming sounds of the modern piano -- became fans of the delicate fortepiano well before the last piece.