Kyrie was written in a three part form reminiscent at the actual form of its namesake in the Catholic mass, however it has no programmatic basis. The number three is a primary organizational mechanism for this piece. Kyrie is based on the Eb dorian mode and contains a number of motives reminiscent of Gregorian chant.
Baxter '07, Brian, "Kyrie (Honors)" (2007). Compositions. Paper 11.