Lessons from a Minnesota concert. Copland's piece worked, his student's didn't - and Perahia saved the day

A concert by the Minnesota Orchestra in its own hall here last month raised some issues that will no doubt linger on long after concertgoers forget the strains of music that accompanied them.

The issues came up in a companioning of works by Aaron Copland and Michael Schelle, a student who came to Copland long after Copland stopped accepting pupils. Since Copland made an exception and took him under his wing, Schelle's ''El Medico'' takes on an added dimension of interest when played in juxtaposition with his teacher's ''El Salon Mexico,'' after which it seems to have been patterned.

It was difficult to listen to these pieces and not think about the issues they raised concerning the value of Copland's ''lighter'' Americana style and its usefulness to modern composers searching for a similarly accessible idiom.

This orchestra's sparkling performance of the Copland piece reaffirmed that we are not listening to the equivalent of an Elmer Bernstein movie sound track. This is just very special music gathered together in a pan-musical, pan-American concoction. The gestures and motifs Copland uses have an elegant bruit all their own.

Would that the same could be said for Schelle's work.

''El Medico'' is a pretty piece of business - composed, we're told, to prove to Schelle's brother that he could write tuneful music. But its studied clamor and effervescence are borrowed from a distant source. They have no life of their own. The interesting point about this piece is that almost identical gestures take on a less compelling coloration in the younger man's work.

Schelle knows what to do with these tools. He just doesn't have any business making contemporary music with them. For him, they are convenient devices; for Copland, they were discoveries.

There was much discovery in the last event of the evening, when pianist Murray Perahia essayed the territory of Beethoven's Piano Concerto No. 3 in C minor. The orchestra - which had sounded luminous but directionless in Mendelssohn's Symphony No. 5 - produced more excitement in response to Perahia's reasoning.

And with good reason. Perahia's phrasing, his lyrical sense, and most of all the direct path he took from one moment to the next, held one spellbound. Some of the playing was a bit filmy and precious for the material at hand. But Perahia largely burst through that veil with some sweeping descriptions of the inner structure.

The Minnesota Orchestra is an extremely pliant and responsive group of musicians, and they produce a thrilling sound. Sometimes, it's too thrilling. The brass got a bit Wagnerian in the Mendelssohn: The sound of an iron tread echoed in the orchestra's stride. But the great, heartfelt third movement came across with a largess of feeling and an utter simplicity of gesture, showing what it can do when it feels moved.

Unfortunately, during most of the night, only Murray Perahia was able to so move them.