He slightly altered the texts of the Introit , the Kyrie , Pie Jesu , Agnus Dei , and In Paradisum .
He slightly substantially changed the text of the Offertory ( described below ) .
He slightly altered the texts of the Introit , the Kyrie , Pie Jesu , Agnus Dei , and In Paradisum , but substantially changed the text of the Offertory ( described below ) .