The title of the work is made up of two words: the Greek πρίσμα (prisma – prism) and the Latin iris (rainbow). Both words are strongly associated with optics. The former refers to the phenomenon of light dispersion. The latter gave the name to the optical phenomenon of iridescence (irradiation).
Both these phenomena have influenced the content of the composition. The former (dispersion) became the basis for the generation of three different tempi in the opening of the work (one for each of the musicians) and for creating the impression of dispersion (release) of a beam of each individual part in relation to the others. We feel that the violin plays at the fastest tempo, the viola at a slower one, and the cello at the slowest. From the very beginning we hear regular rhythms, which are in fact the same for each of the instruments, but performed at three different tempi, related to each other by the simple ratios of 2:3 and 3:4.
Against the background of these rhythms, as in the process of iridescence, there appear increasingly more ornaments, instrumental gestures and runs, which enrich the raw rhythmic part known from the beginning of the piece. These ornaments sparkle more and more. They are like opalescent colours appearing on the multilayered surface of transparent or translucent bodies (such as pearl mass, gasoline stains, or soap bubbles) as a result of iridescence, which in turn is a consequence of light wave interference.