If we can believe the music that was heard last night in the University of Maryland's Tawes Theatre, Johann Sebastian Bach was an interesting but rather primitive and simple-minded predecessor of Frederic Chopin. Obviously, we cannot believe that music.

The program, titled "Bach Meets Chopin," was performed by Brazilian pianists Joao Carlos Martins and Arthur Lima, and on paper it looked fascinating. Martins played the 24 preludes from Book I of Bach's "Well-Tempered Clavier," alternating with Lima, who played the 24 preludes of Chopin's Op. 28. It is an interesting exploration of what happened to a musical idea in the leap from the baroque to the romantic temperament, but it was ultimately unfair to Bach.

In Bach's keyboard music, a prelude was usually composed to lead into a fugue or a suite of dances. It allowed the player to warm up and show a bit of technical flash, but above all, a Bach prelude is intended to introduce something else.

Chopin's preludes, which vary greatly in length, style and emotional intensity, are designed to stand alone as independent pieces--a fact that makes their title semi-meaningless but does not undermine their musical value. They were written for the piano and exploit all of its qualities superbly. They make the keyboard whisper, sing, laugh and weep in ways that were far from Bach's style or purposes.

Bach's preludes are more abstract in their structures and not usually designed to stand alone as a complete musical experience. They were not composed with the piano in mind, though they can be played on the piano. When they are played in tandem with Chopin's preludes, the temptation is almost irresistible to modify them--to overuse the pedals, throw in an occasional crescendo (which was impossible on Bach's instrument, the harpsichord), and in general to romanticize the music. Martins resisted these temptations sometimes, but he seemed to have ambivalent feelings about how to interpret Bach. He is considerably more succesful in his piano recordings of Bach for Arabesque Records, which will ultimately include all of the composer's solo keyboard works.

Lima's assignment, in the circumstances, was considerably easier, and his Chopin was powerful, fluent, idiomatic. The program helped to show what Chopin learned from Bach. But it did not really do justice to the work of the Leipzig master.