Plagal Mode - History

History

The name of Pope Gregory I was attached to the variety of chant that was to become the dominant variety in medieval western and central Europe (the diocese of Milan was the sole significant exception) by the Frankish cantors reworking Roman ecclesiastical song during the Carolingian period (McKinnon 2001). The theoretical framework of modes arose later to describe the tonal structure of this chant repertory, and is not necessarily applicable to the other European chant dialects (Old Roman, Mozarabic, Ambrosian, etc.).

The repertory of Western plainchant acquired its basic forms between the sixth and early ninth centuries, but there are neither theoretical sources nor notated music from this period. By the late eighth century, a system of eight modal categories, for which there was no precedent in Ancient Greek theory, came to be associated with the repertory of Gregorian chant. This system likely originated from the medieval Byzantine oktōēchos, as indicated by the non-Hellenistic Greek names used in the earliest Western sources from about 800 (Powers 2001b, §II.1(ii)). Ignorant of these developments, Hucbald (840–930) created a series of eight modes (Powers 2001a).