source file: m1353.txt
Date: Fri, 13 Mar 1998 09:55:15 -0800 (PST)

Subject: Modes

From: John Chalmers <non12@deltanet.com>

Charles: The ancient Greek names for the heptatonic modes are correct
in your post.  To avoid accidentals, the key of C major is
used and the various modes occur as octave species in the order
Mixolydian (B-b), Lydian (C-c), Phrygian (D-d), Dorian (E-e),
Hypolydian (F-f), Hypophrygian (G-g), and Hypodorian (a-a').

The extinct Ionian mode was a G mode and the Aeolian and Locrian 
were A modes, but it is not known how these differed from the HP 
and HD modes. The Mixolydian was also called Hyperdorian and the 
lower A mode (on the note Proslambanomenos) was called Hypermixolydian 
and Hyperphrygian. (In Argos, it was outlawed because it had no ethos of
its own, but was merely a lower octave repetition of the Hypodorian.)

Greek music was based on a 15-tone two-octave gamut running in our 
notation from A-a-a', to which an accidental b-flat was added to
illustrate modulation at the fourth. This system  could be taken
at various pitch levels (see below). The absolute pitch is not known 
and may have been irrelevant in any case.

In musical practice, these modes were transposed so that the modal 
patterns of all 7 species moved into the middle range of the two octave 
system. Thus a system of pitch keys developed at roughly semitonal 
intervals. These keys took the names of the modes and new names 
(Hyperionian, etc.) were coined to complete  a set of 15 keys or TONOI. 

The center of the system was also changed from Dorian (E)
to Hypolydian (F) and two series of names were applied (high
and low Dorian, etc.).

In the Middle Ages, confusion arose between the keys and the modes
and the order of the modal names was reversed. Schlesinger attributes
this error to Boethius. Later, other ecclesiastical names were invented
as musical practice changed. The plagal/authentic distinction 
developed at that time.

To avoid confusion, one should always specify whether Greek or 
ecclesiastical nomenclature is being used unless the context is
clear.

--John