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they do nowadays, modulating between scales and rhythms: in each set-piece (nomos) they used to preserve the appropriate tuning throughout.7 |
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There are other references to modulation of mode and genus as a feature of citharodes' style in the late fifth and early fourth centuries,8 and it is a subject discussed by the theoreticians.9 They distinguish four categories of melodic modulation: |
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1. modulation of genus, e.g. from diatonic to chromatic or en-harmonic; |
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2. of scale-constitution (systema), i.e. from a conjunct to a disjunct sequence of tetrachords, or vice versa; |
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4. of ethos, e.g. from grand to sensuous, or from calm to vigorous. |
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Ptolemy interprets the second type as being essentially a change of key; but he draws a crucial distinction between this sort of modulation, which (like modulation of genus) palpably alters the contours of the melody, from the sort of key-change by which the melody is transposed to another pitch without its internal structure being affected. |
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In the musical fragments we fail to recognize any instance of the latter type of key-change.10 We do find examples of (a) alternation of diatonic with chromatic, in Hellenistic texts (Vienna fragments, Delphic Paeans). (b) Modulation between conjunct and disjunct systems, both in Hellenistic and in later pieces (Vienna fragments, Delphic Paeans; 47 POxy. 3162). The tonic may remain the same, or be shifted by a tone; thus a scale e f g a b c' d' e' (disjunct tetrachords with tonic a) might change either to e f g a  c' d' (tonic still a) or to  gab c' d' e' (tonic b). Cf. p. 191. (c) Shift of melodic focus to a different degree of the scale without change of the scale itself. This seems to occur at all periods, and it is probably not always to be |
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7 Ps.-Plut. De mus. 1133b. Phrynis belongs to the third quarter of the 5th c. For nomos see below, p. 215. |
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8 See Ch. 12. |
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9 Aristoxenus' discussion, programmed at Harm. 2. 38, is lost, but reflected in those of later writers: Cleon. p. 204. 19-206. 5, Aristid. Quint. pp. 16. 24, 22. 11-26, 29. 12-14, Bacchius pp. 304. 6-22, 312. 7-11, Anon. Bellerm. 65: a more independent account in Ptol. Harm. 2. 6. Cf. E. Pöhlmann, Griechische Musikfragmente (Nürnberg. 1960), 51-3; Barker, GMW ii. 424 n. 126: also Phrynichus. Praeparatio Sophistica p. 24. 16 Borries. |
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10 In one of the Vienna papyri (8 PVindob. 29825 ft. a/b recto 6 and verso 11) there are signatures 'Phrygian' and perhaps 'Lydian' marking changes of notation-key, but the fragments are too exiguous for us to judge the melodic significance. |
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