Offertories belong to the Proprium of the mass such as the Introitus, the Gradual, and the Communion. They have been accompanied instrumentally to a great extent contrary to the other parts of the Proprium . By the addition of instrumental interludes, recitatives and arias they could be enlarged to a form similar to cantatas. Even the textual choice often exceeds the liturgical texts what Rathgeber did best in the offertories of Opus IV whereas he uses only liturgical texts in Opus XIV.