Q. Why is a selection from the Book of Psalms always included in the Mass?
A. The lectionary reading in Mass designated as the “Responsorial Psalm” is most often from the Book of Psalms, but not always. It may be a psalm-like passage from another biblical book. For example, the “Responsorial Psalm” for December 22 is “The Song of Hannah” from 1 Samuel chapter 2.
Even so, the custom of including a “psalm” of some sort in every Mass goes back to the Jewish roots of Christian worship. Since ancient times, the Psalms have been the principal “hymnbook” of the Jewish people, an indispensable part of their liturgy. Not surprisingly, then, since the earliest times of the Church, this most beautiful of biblical books has been an essential part of Christian worship. PT