Heptonia Prima and Secunda

Heptonia Prima and Secunda
The rather unwieldy name of Heptonia Prima and Heptonia Secunda are given to the


various seven-note scales which can be formed using tones and semitones but


without two semi-tones appearing in succession. Some are more theoretical than


others. They are


Heptonia Prima
Beginning on keynote A and working up the notes of the 'natural minor' scale


(A,B,C,D,E,F,G,A), the seven modes are:


Aeolian mode (natural minor)


Locrian mode


Ionian Mode (major)


Dorian Mode


Phrygian Mode


Lydian Mode


Mixolydian Mode


It may be noted that the Dorian is exactly the same descending as ascending. The


less common series is


Heptonia Secunda
The difference between this and the diatonic modes is that they have two and three


tones between each semitone, while these latter modes have one and four. These


are sometimes called modes of the melodic ascending minor since that is the most


commonly used scale of this type, but other modes can be produced by starting on


the different scale notes in turn. Thus starting on keynote A as above and following


the notes of the ascending melodic minor (A,B,C,D,E,F#,G#) yields these seven


modes:


'Melodic ascending minor'


'Phrygian raised sixth' combines the Phrygian flat second and Dorian raised sixth


'Lydian raised fifth' combines the Lydian fourth with a raised fifth


'Acoustic' or 'Lydian-Myxolydian' Scale So-called because close to the scale built


on natural overtones and combines Lydian raised fourth with Myxolydian flat


seventh


'Major minor' scale Like natural minor (aeolian) but with a major third


'Half diminished' or 'Locrian sharp 2' scale This is like the Locrian with a raised


second


'Altered scale' Like Locrian with flat fourth


These modes are more awkward to use than those of the diatonic scales due to the


four tones in a row yielding augmented intervals on one hand while the one tone


between two semitones gives rise to diminished intervals on the other. For example,


the last two modes listed above both have 'Locrian' diminished triads built on their


tonics given them unstable tonality while the fourth mode not only has an augmented


fourth a la the Lydian mode but also an augmented fifth making the dominant and


subdominant unusable.