A Dictionary of Music and Musicians/Sext
SEXT (Lat. Officium (vel Oratio) ad Horam Sextam; Ad Sextam). The last but one of the 'Lesser Hours' in the Roman Breviary.
The Office begins, as usual, with the Versicle, and Response, 'Deus in adjutorium.' These are followed by a Hymn—Rector potens, verax Deus—which never changes; Verses 81–129 of the Psalm, 'Beati immaculati,' sung in three divisions, but under a single Antiphon; the 'Capitulum' and 'Responsorium breve' for the Season; and the Prayer (or Collect) for the Day.
In Collegiate Churches, the Offices of Terce and Sext, are usually sung immediately before and after High Mass. The Plain Chaunt Music for the various Offices is contained in the Antiphonarium Roman um, and the Directorium Chori.[ W. S. R. ]