Donald O. Johnston - Missa Brevis
MISSA BREVIS (A Short Mass for concert performance).
Although rich in the use of tertian harmonies derived from the major/minor system of music
construction, MISSA BREVIS is fraught with the ancient harmonic system known as Organum. In the
tertian system of harmonic construction, harmonies are built from major and minor 3rds organized
upon a prime note to create chords (Root, 3rd, 5th). In the system referred to as Organum (used in
music in the Roman Catholic tradition of the 9th to early 13th centuries) harmonies are created out of
perfect 4th or 5th harmonic intervals (no 3rds) which yields an ancient harmonic effect.
The Praeludium to MISSA BREVIS opens with major and minor harmonies in homophonic
construction performed by the Brass Choir. Organum harmonies prevail in the following choral
rendition of the KYRIE/CHRISTE/KYRIE section.
The GLORIA serves as an introductory display to introduce the SANCTUS. The AGNUS DEI is a
quiet, solemn closing, using a Gregorian style chant melody to gently close the Mass.