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(subdivided into three smaller steps) and a fifth (subdivided into four), making up an octave (for example, d-g: g-a-d', or d-g-a: a-d'). A pair of conjunct tetrachords, with the addition of a tone at the top or bottom, likewise make up an octave resolvable into a fourth + fifth, or fifth + fourth. These are in fact the ways in which the octave, where it appears in Greek music as a significant entity, is constructed. The three alternatives are shown in Fig. 6.1. The tone not included in the tetrachords is called the disjunction (diazeuxis). |
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FIG. 6.1.
The construction of the octave in Greek music |
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Not all music had a compass as wide as an octave. As we shall see, some music did not extend over even two conjunct tetrachords (a seventh). Yet always, so far as we can see, the intervals of the fifth and especially the fourth had a cardinal place in any scale. These lesser spans are of more fundamental and primordial importance in Greek music than the octave compounded from them. |
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The anatomy of the fourth |
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The scales familiar to us in Western music are diatonic, that is, they are made up of steps that are never larger than a tone nor smaller than a semitone. Two tones and a semitone make up a fourth, three tones and a semitone make up a fifth, so that a typical octave scale has a form such as |
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