Barra based his Missa Ecce panis angelorum on three pre-existing melodies: Ecce panis angelorum, Bone pastor and O salutaris hostia. The first two appear in the sequence Lauda sion salvatorem and the last in the hymn Verbum supernum prodiens, both composed by St. Thomas Aquinas for the Feast of Corpus Christi. For this reason this composition fits particularly well into the repertory of the Occo Codex, roughly the first half of which can be associated with the sacrament of the Holy Eucharist.

The Missa Ecce panis angelorum is exemplary of its generation with regard to compositional technique. The cantus firmi are most closely paraphrased in the tenor, but a considerable amount of more freely composed motives derived from these melodies nonetheless ends up in all the other voices, by means of imitation and canons. Typically, frequent contrasts occur in this composition, such as lengthy duets versus rich four-part fragments and lively melismatic versus strictly homophonic passages.

In the Sanctus all three cantus firmi come into focus simultaneously.¹ In the Osanna the three melodies - all fragments of chants composed for the celebration of the Holy Eucharist, as noted above - figure simultaneously in a five-part setting, the only one in the entire composition. Long note values and striking homophony further stress this particular section. The remarkable passage at this location in the mass was surely intended musically to underscore the "sanctity" of the most respectable of sacraments (venerabile sacramentum): the Holy Eucharist.

The mass is transmitted in four manuscripts: BerlS 40091, BrusBr IV.922 (the Occo Codex), CambraiBM 4 and VatS 26, in all cases nearly complete. Between the versions in the Occo Codex and the other three, there are no less than 82 variants of pitch and rhythm and about 140 rhythmic substitutions. Here, some very typical and interesting similarities between the different versions emerge, especially between BerlS 40091 and VatS 26 and sometimes also CambraiBM 4, suggesting that these versions were derived ultimately from the same source. On the other hand, in CambraiBM 4 an Agnus Dei III section appears which is absent in all of the other sources (where there are only an Agnus Dei I and II). It is however very likely that this Agnus III does belong to the Missa Ecce panis angelorum: the melodies, motives and compositional techniques are very like the ones used throughout the entire composition. This suggests that the transmission of the version in CambraiBM 4 would have taken place separately from that of the other three, but does not explain the parallels between CambraiBM 4, BerlS 40091 and VatS 26. It seems therefore that the sources available do not currently allow a confident reconstruction of the mass's transmission.

Pre-existent material: Plainchant Ecce panis angelorum and Bone pastor (verses of sequence Lauda sion salvatorem), treated as basis of melodic lines and points of imitation

Paris, Bibliothèque nationale, MS lat. 14452, f. 241r-v (Gradual of St. Victor of Paris, section dated 1567)

Editorially supplied material: Plainchant intonations of Gloria and Credo supplied from Paris, Bibliothèque nationale, MS lat. 14452, f. 243r-v (Gradual of St. Victor of Paris, 13th century, with additions dated 1567)

Notes
[1] For further discussion, see Mary Jennifer Bloxam, A Survey of Late Medieval Service Books from the Low Countries: Implications for Sacred Polyphony, 1460 - 1520 (Ph.D. diss., Yale University, 1987), pp. 417-23.