My editions of these motets are in PDF format and ready to download. More are in preparation and will be added. At this juncture, Carus-Verlag may be considering the publication of some of this music, so some links may be inactive. If you wish to download the available music, the only request is that proper reference is made to MusikHaus and James D. Feiszli for making the music available. All editions are copyrighted and it will be considered a violation of copyright to use this music to create editions under other ownership.
If you know and like Gregorian chant, you will adore this music.
The Formschneider print contains over 350 plainsong-based motets, setting into polyphony the chants of the Mass Proper for most feasts of the church year in the years prior to the Council of Trent and specific to the area stretching from Constance to Vienna. It also includes five settings of the Ordinary of the Mass. Brown (1976) described it as a “comprehensive compendium of virtually all devices, manners and styles prevalent at the time”.
Each motet is based on the corresponding chant for that Proper item. Sometimes the chant appears verbatim in phrases, sometimes it is paraphrased. In some motets one voice predominantly carries the chant while the other voices support it. In others, the chant appears in all voices at different times.
Each Proper has the same basic set of motets: introit, alleluia, sequence, communion. Depending on the season of the church year Proper items appear or disappear; e.g., the alleluias are replaced by tracts during Lent. The gradual Haec Dies appears for Easter Sunday in addition to an alleluia and a sequence.
The shorter motets (introits, alleluias, communions) are suitable for liturgical services, generally lasting between 1-4 minutes in length. The introits and alleluias are equally suitable for concert performance.
The sequences are the tour de force of the Choralis Constantinus, requiring great keyboard improvisation skills or good plainsong interpretation and superb rhythmic sense by singers due to the complexity of the rhythm. Sequences were victims of the liturgical reforms of the Council of Trent for obvious reasons. If performed as intended, a sequence might last for 10-12 minutes. When coupled with the adjoining alleluia, the performance would be: alleluia-alleluia verse-sequence-alleluia. That would be quite the concert in the middle of a liturgical service! The sequences in the CC are set in alternatim style, meaning that only every other verse appears in polyphony. Mahrt (1970) theorized that the non-polyphonic verses were probably improvisations of the chant on the organ. The late Dr. Mary Berry of Cambridge University and noted Gregorian chant scholar, with whom I studied in 1993, was convinced that chant performance in the fifteenth century often took the form of long-held notes sung by the choir while the organist improvised. Berry’s theory and Mahrt’s thesis find common ground in the physical evidence left by Hans Buchner, organist at the Constance cathedral during the composition of the CC. Buchner’s relationship with Isaac is not clear, but it is known that he was a student of Paul Hofhaimer, organist for Maximilian’s chapel. Three sequences that occur in the CC – always polyphonic settings of the even-numbered verses – are in the same keys as Buchner’s settings of the odd-numbered verses of the same sequences. Lacking a good organist (or organ), it is equally possible that the alternate verses could be performed as chant by a soloist or small group.