Music from the Earliest Notations to the Sixteenth Century

borrowed from Boethius, the authority of authorities. Boethius had adopted these names from late Greek
(Hellenistic) sources, where they had referred not to what we would call modes but to what the Greeks
called tonoi, transpositions of a single scale rather than different diatonic scales. Thus the familiar Greek
nomenclature of the medieval modes was actually a misnomer, first perpetrated by an anonymous ninth-
century treatise called Alia musica (literally, “More about Music”); but there is not much point in trying to
rectify that now. (Note that the Greek prefix hypo-, attached to the names of the plagal scales, is roughly
synonymous with the word plagal itself: both mean “lower.”) Ex. 3-2 also includes the tubae of the
corresponding psalm tones, for these were sometimes claimed by contemporary theorists to pertain to the
church modes as well. The tuba of an authentic mode lies a fifth above the final, as already observed in
chapter 1. The tuba of a plagal mode lies a third below that of its authentic counterpart. Note that
wherever, according to these rules, the tuba would fall on B, it is changed to C. This was evidently
because of an aversion to reciting on the lower note of a semitone pair. Note, too, that the tuba of the
fourth tone is A rather than G by the regular application of the rules: it is a third lower than its adjusted
counterpart (C in place of B transposes to A in place of G).

EX. 3-2 The eight   medieval    modes

Perhaps the most important thing to bear in mind regarding this array of medieval modal scales is that
the staff positions and their corresponding “letter names” do not specify actual pitch frequencies, the way
they do in our modern practice. Thus one must try to avoid the common assumption that the Dorian scale
represents the piano’s white keys from D to D, the Phrygian from E to E, and so on. Rather, the “four