User:Platonykiss/Phthora (music)

Phthora (gr. φθορά, "destroyer") is one of the great signs used in Byzantine notation. In its simplest form it is abbreviated by its first letter "φ" and several phthorai were derived by turning this letter. Since the Hagiopolites treatise, the concept of phthora has changed during the history of Byzantine music theory.

The Phthorai of the Hagiopolites
Already the Hagiopolites, presumably a 9th-century treatise which served as an introduction of a chant book tropologion, mentions two phthorai which add to the diatonic eight modes of the octoechos (Ὀκτώηχος) two other modes. And mode is here defined as a melodic model which has its own intonation formula and its own cadence formulas which allow the design of a chant composition according to the syntactical structure of a text:

φθοραὶ δὲ ὠνομασθήσαν, ὅτι ἐκ τῶν ἰδίων ἤχων ἀπᾶρχονται, τελειοῦνται δὲ εἰς ἑτέρων ἤχων φθογγὰς αἱ θέσεις αὐτῶν καὶ τὰ ἀποτελέσματα.

They were called Phthorai (i.e. destroyers), because they begin from their own Echoi, but their endings and cadences are on notes [ φθόγγοι ] from other Echoi.

And these two phthorai were called after the syllables of the intonation "nana" (νανὰ) and "nenanō" (νενανῶ).

The Phthorai of the Papadikai
Phthorai can be used as modulation signs as well as alteration signs. Theoreticians as the anonymous author for instance in a treatise of codex 899 of the National Greek Library (EBE) in Athens, try to explain the difference between echos (mode), modulation, and alteration of diatonic degree:

Εἰσὶ δὲ καὶ φθοραὶ δύο, αἵτινες ψάλλονται σὺν αὐτοῖς, τὸ νανὰ καὶ τὸ νενανὼ. Εἰσί δὲ καὶ ἄλλαι φθοραὶ τῶν ἄλλων ἤχων ἀλλοὐκ εἰσὶ τέλειαι ὡς αὗται. Εκεῖναι γὰρ δεικνύουσιν ἐναλλαγὴν μερικὴν ἀπὸ ἤχου εἰς ἕτερονἶ αὐταὶ δὲ τέλειαι οὖσαι ἔχουσι καὶ κρατήματα ποινθέντα παρὰ τῶν κατὰ καιροὺς ποιντῶν ὡς εἰς κυρίους ἤχους, καὶ εἰκότως ἄν [τις] καλέσειεν αὐτὰς τελείους ἤχους καὶ οὐ φθορὰς.

"There are two additional phthorai which used to be sung with them [the eight echoi of the Hagiopolitan Octoechos ], 'nana' and 'nenano'. There are the phthorai of the other [diatonic] echoi as well, but those are not as perfect. They [all] cause a temporary change during a transition from one echos to another, but only the former have been regarded as so prefect, that kratemata had been made of them by composers over generations as if they were the dominant [authentic] echoi (kyrioi echoi). Hence, they could be rather called 'perfect echoi' than 'phthorai'."

These concepts are very difficult to explain without recourse either to a staff system notation, to a mathematical framework of ratios of frequencies of pitches, or to an experimental framework of lengths of sounding strings or pipes. Thus, the distinction between mode, modulation and alteration remains somewhat unsharp in the notational system.