Note 9 — IX THE SYSTEMS OF HUCBALD AND GUIDO D'AREZZO—THE BEGINNING OF COUNTERPOINT
Reading edition
There is much question as to Hucbald's organum. That actually these dissonances were used even up to 1500 is proved by Franco Gafurius of Milan, who mentions a Litany for the Dead (De Profundis) much used at that time: