It is with this splendid collection of Christmastide music that Byrd's second book of Gradualia opens. It includes the complete Propers for the principal (third) mass of Christmas Day, which are used throughout the Octave, together with settings of Hodie Christus natus est (Magnificat Antiphon), O magnum misterium/Beata Virgo (Matins Respond) and O admirabile commercium (Magnificat Antiphon for the Circumcision (Jan. 1)).