finals” and their concomitant scales represent nothing more than the most convenient way of notating
intervallic patterns, relationships between pitches that can be realized at any actual pitch level, the way
singers (unless cursed with “perfect pitch”) can at sight—or rather, by ear—transpose the music they are
reading, wherever it happens to be notated, to a comfortable tessitura or “placement” within their
individual vocal ranges. What we are now conditioned to regard as fixed pitch associations (e.g., “A-
440”) were at first no more than notational conventions.
If this is a hard idea to get used to, imagine a situation in which all pieces in the major were written
“in C” and all pieces in the minor “in A,” regardless of the key in which they would actually be
performed. Only instrumentalists, whose physical movements are coordinated with specific pitches, or
singers with perfect pitch, who have memorized and internalized the relationship between specific
frequencies and the appearance of notated music, would be seriously discommoded by such an
arrangement. Such musicians can only transpose by mentally changing clefs and signatures. And as we
shall see, it was the rise of an extensive independent repertory of instrumental music in the seventeenth
century that brought about our modern “key system,” in which actual pitches were specified by notation
and in which key signatures mandated specific transpositions of the standard scales.
A NEW CONCEPT OF MODE
Thanks to the work of the “tonarists” who coordinated the Roman antiphons with the psalm tones, and the
theorists who drew general conclusions from the tonarists’ practical observations, a new concept of mode
arose. Instead of being a formula-family, a set of concrete, characteristic turns and cadences arising out of
long oral tradition, a mode was now conceived abstractly in terms of a scale, and analytically in terms of
functional relationships (chiefly range and finishing note or final). We owe this change, on which all our
own theoretical notions of musical “structure” ultimately depend, and the classifications and terminology
outlined above, primarily to the work of two Frankish theorists of the ninth century.
Aurelian of Réôme, the earlier of them, was a member of the Benedictine abbey of St. Jean de Réôme
in what is now the Burgundy region of France, southeast of Paris. His treatise, Musica disciplina (“The
discipline of music”), was completed sometime around 843. Beginning with its eighth chapter, subtitled
“De octo tonis,” it consists of the earliest description (or at least the earliest naming, for it is
impressionistic and nontechnical) of the eight church modes with their pseudo-Greeky tribal names.
Aurelian changed the order of the tones from what it was in Byzantine theory. Instead of grouping the four
authentic modes together and following them with the four plagal modes, Aurelian paired authentic modes
with plagal ones that shared the same finals, thus enhancing the role of what we now call the “tonic” in
establishing a tonality. Aurelian’s chapter on psalm recitation contains the oldest extant notations in early
Frankish neumes.
Hucbald (d. 930), a monk from the abbey of St. Amand, was the real genius of medieval modal theory.
His treatise, De harmonica institutione (“On the principles of music”), thought to have been completed
around 880, is a far more original work than Aurelian’s and far less dependent on the received academic
tradition. It was the earliest treatise to number the modes, following the order established by Aurelian,
straight through from one to eight. It is also the earliest treatise we have that replaces the relativepitch or
interval/degree nomenclature of ancient Greek music—the so-called Greater Perfect System, transmitted
by Boethius—with the alphabet letter names still in use. The name of the lowest note of the Greek system,
proslambanomenos, was mercifully shortened to “A,” and the rest of the letters were assigned from there.
Hucbald did not, however, recognize what we now call “octave equivalency,” but continued the series of
letters through the full two-octave compass of the Greeks, all the way to P. Modern usage, in which A