2 Some chants have become standard melodies for films, in particular the "Dies irae" from the Roman Catholic Mass for the Dead. The "Dies irae" is, in fact, one of the most frequendy heard chants in film, used in television theme songs, commercials, and even a Christmas film(Ifs a Wonderful Life).
Gregorian chant, monophonic, or unison, liturgical music of the Roman Catholic Church, used to accompany the text of the mass and the canonical hours, or divine office. Gregorian chant is named after St. Gregory I, during whose papacy (590 604) it was collected and codified.