Cynthia Folio: Pentaprism is based on a five-note motive. The title is derived from a five-sided prism, found in many cameras, that transforms a beam of light by 90 degrees. Throughout the piece the motive is altered as if heard through a prism. The initial appearance of the motive (G-Ab-G-Eb-C)—a simple major seventh chord—is revealed one note at a time over a span of twelve measures. The piece ends by reversing the process, by “erasing” the motive one note at a time until only the first note remains. The form is a kind of arch with a climax before the coda, where the major seventh chord is expressed in an unabashedly diatonic context.
The principal players in each section are featured as soloists for two reasons: first, this mimics the idea of contrast between solo and ensemble that is embodied in the Mozart concerto; second, the pairing of professional musicians with students allows a degree of virtuosity for the more seasoned performers.