RESPONSORY. – In the Mass, after the reading and in the Office at the end of each lesson and in the minor hours after the Chapter, the soloist sings or recites a verse of a psalm or a passage from Holy Scripture to which the choir responds.
The first and second are called r. prolixum, the rest r. breve. Its origin lies in the need to allow the readers to rest between one passage and another and also to provide some variety in the liturgical function. The r. is indicated by the letter R and is divided by an asterisk into two or three sections, one of which is called Repetenda, and by a versus, sometimes more than one, with the final doxology of the Gloria Patri in the last r. of each Nocturn and in every r. breve, except during Passiontide. In the Office of the Dead, the Requiem is used in its place.
The manner in which responsorial psalmody was sung in the early centuries when it was introduced is unknown. One may suppose, based on an allusion by St Augustine, that the soloist’s verses and the choir’s response were performed with recitatives and melodies much simpler than those of our r. breves and the current invitatories. Later, almost all the melodies became more ornate and the number of verses was consequently reduced, so that it is very rare to find in medieval manuscripts an r. with more than one verse. In current usage this latter form is found only in the r. Aspiciens a longe and Libera.
Among the different musical forms derived from ancient responsorial psalmody, only three have retained the name of r. One occurs in the first part of the Mass; it is the gradual, whose structure was altered by the suppression of the refrain after the verse. The melody of the verse is highly developed: almost always constructed on a scale higher than that of the first part of the r., it offers the soloist the opportunity to perform his part with great virtuosity. The graduals were composed and most frequently set in the mode of F, which deserves particular attention insofar as this mode was the one employed in all other genres of Gregorian music.
The other two forms of r. are found in the Office: the r. breves, performed with very simple melodies, and the long r., which is often composed of formulas but of a