by the use of
musia ficta
: composers routinely altered pitches to achieve the desired
result. For example, the “softening” of the fourth scale degree in Lydian, or adding
a
Leading Tone
to Dorian and Mixolydian.Because of its unique character, Phrygian
was resistant to any alteration.
Figure 3.17
Modes and music ficta
Greater Modal System
In practical composition, the altered version of the mode became the version used.
The resulting mixtures of mode and alteration in time yielded new scales,
recognized as such by established practice. This was codified in the Greater Modal
System.
Figure 3.18
The Greater Modal System (Abbreviated)
Audio 12
The Modes
Note that Ionian is the Major scale and Aeolian is the Natural Minor scale. The other
earlier modes (again by established practice) gradually polarized toward one or the
other of these two forms. Due to the perceived flaws of each mode, they eroded
under the weight of their own inefficiency and distilled into either the “Major”
mode, or the “Minor” mode. The Locrian mode, while recognized as a theoretical
mode was not used in practical composition due to its unstable final
resolution.Locrian was not included in the system of modes until 1482 where it was
Chapter 3 The Foundations Scale-Steps and Scales
3.4 Heptatonic Scales: Introduction to Modes
108