A six-voice mass by Cornelius Canis on his own motet, unique in the Leiden Choirbook C. The final Agnus Dei is scored for eight voices (SSAATTBB). You can buy or download this score here.
We start our editions of music from the Leiden Choirbooks with this beautiful four-voice motet by Johannes Cleeff (Johannes de Cleve) from Codex A (NL-L MS 1438).