The origins and authorship of a fifteenth century mass found in Siena, Biblioteca comunale degli Intronati, K. I.2, have been subject to much scholarly debate. This mass uses a variety of songs as cantus firmi, most of which remain unidentified. The identification of two cantus firmi, however, supports the idea of Obrecht as composer of the Siena mass. One cantus firmus from the Agnus Dei of the Siena mass is found in the Agnus Dei of Obrecht’s Missa Plurimorum carminum I. The second cantus firmus is derived from the German chorale Ach Gott von Himmel sieh darein, first published in 1410 as a German song with the words Begirlich in dem hertzen min. Two other works also borrow this chorale, Obrecht’s Laet u gehnoughen liever Johan and an anonymous Gaude mater in gaudio. The similarities in melody and structure between these three works lead to the conclusion that Obrecht composed both the Gaude mater in gaudio and the Siena mass.

Works: Anonymous: Missa (Siena, Biblioteca comunale degli Intronati, K. I.2) (447-76); Gaspar van Weerbeke: O salutaris hostia (457-71); Anonymous: Gaude mater in gaudio (457-71); Obrecht: Laet u ghenoughen liever Johan (457-71).

Sources: Obrecht: Missa Plurimorum carminum I (456-58, 471-77); Anonymous: Begirlich in dem hertzen min (456-71).

Index Classifications: 1400s

Contributed by: Amanda Jensen