The discovery of this mass is a piece of luck. Up till now it was a only matter of knowledge that Rathgeber dedicated a mass to Gerold Haimb, prince abbot of Muri, due to the anniversary of the abbot's benediction on October 9, 1731. Rathgeber got a 10 goulds and 20 Schilling reward. The gambist and singer Thilo Hirsch, linked to the ensemble arcimboldo/Basel, found by chance a manuscript in the music library of the monastery of Einsiedeln, dated to 1736, that contains an anonymous "mass of Muri". After comparing the manuscript with the last mass of Opus XII part II, the Valentin Rathgeber-Society could proove that both compositions are nearly identical. Thus, Rathgeber  published the same composition in his volume Opus XII part II dedicated to Dr. Anton Cajetan of Unertl, the Dean of St. Peter/Munich and provost in Habach, and received double funding for one and the same composition. The manuscript is not an autograph of Rathgeber himself. The single sheets stem from distinct writers since the handwriting is different.  Contrary to the printed version, the "Mass of Muri" is written in C. The Soprano Aria in Benedictus appears in the manuscript as a partly altered Alto Aria. Instead of the Tenor Aria in Agnus Dei  the manuscript has got a different Bass Aria.  Except for that both editions are identical. However the printed version is much more authorative.

The Valentin-Rathgeber-Society has edited the music sheets so that the "Mass of Muri" could be performed in the famous abbey of Muri already on Martini 2006 . A delegation of Oberelsbach came to Muri for that occasion.  By now, an excellent  CD recording of  this mass by the Cappella Murensis and ensemble arcimboldo is available, released by Audite.