Dimitri Koubaroulis: Iakovos' Doxology starts high from the Authentic mode (KE) and ends in its Plagios (PA). Byzantios' one starts from Plagios (PA) and ends in the Authentic (KE).

Ioannis Arvanitis: In brief: First, this doxology is clearly labeled "Protos Tetraphonos" in the manuscripts. Because of the little use of this mode in this period and of the great similarities of the musical phrases in this doxology to the formulas of sticheraric Plagal 1st, it was relabeled to Pl. 1st (the opposite happened with "Osoi eis Xriston").

Dimitri Koubaroulis: Interesting. So from what you are saying, Byzantios wrote it as First Mode Tetraphonos and Stephanos/Ioannis relabelled it to Plagal First Tetraphonos in their printed books (perhaps following a tradition of their predecessors). So, Yianni, if we wanted to be historically correct we should label the doxology as First mode Tetraphonos. Apart from that though, in terms of the melody, what is the right label? If it sounds and moves like Plagal First mode, then it should have been originally labelled as such and the error is with the manuscripts and not with the printed books. If on the other hand is wrongly labelled as Plagal, what would the justification be? The main difference I see in the two doxologies is that Iakovos' does endings on PA (the basis of the Plagal) whereas Petros does endings on KE (the basis of the Authentic). Does that tell us anything?

See answers next to the verses.

Dimitri Koubaroulis My view is that the whole phrase "Oti sy ei monos Agios" is in the same mode (Agia hard diatonic) with ZW flat and GA diesis/sharp (that is natural but melodically attracted (elxis) by DI. The oligon with homalon in the syllable "MOnos" I would interpret as DIKE-KEDI. For that whole phrase I would put isokratema DI (as Agia). My answer is justified by looking at the exegesis of the same Doxolgy in Pandekte (1851) where the first note of this verse is Petaste with klasma on ZW flat (indicated with fthora). Therefore, GA natural. (which gets attracted slightly by DI and becomes diesis)

Ioannis Arvanitis: I would not put a Ga diesis in the theseis you mention. Even Karas, who is so fond of dieseis, has it natural. In any case, the tonality of Agia hard diatonic is not yet established in the beginning of these verses. It is clear only in the descending (a)giiiios, and not at all apparent in "Oti para soi phgh zwhs". The latter can be thought simply as a phrase of Pl.1st triphonos [that is, starting from the vicinity of triphonia of Pl.1st =Di, and ending on this, not showing clearly the quality of the mode based on triphonia but 'depending' on the plagal].

Dimitri Koubaroulis:So you agree that GA is natural there but you disagree on whether it is attracted (elxis) by DI. Chanting it again with elxis and without elxis tells me you are probably right, it sounds more natural to not do the elxis but then you need to explain to us what is the difference of Plagal First Triphonos and the mode based on triphonia of Plagal First (I take it that you mean Agia hard diatonic). It sounds to me that you are saying "this is just Plagal First mode that moves around DI and does a temporary ending on DI and DI is not a dominant note of Plagal First so it doesn't attract GA towards it". Right? Konstantinou however, in his Theoretikon (p. 99) seems to disagree with you when talking about this Plagal First Triphonos (actually he calls it "Triphonon") that you mentioned. He says that "temporary stop on DI in that mode attracts GA towards it" and gives the end of the well known Xristos Anesti (-samenos) as an example. What can you say about that?

Dimitri Koubaroulis: Exactly as we did in "Oti sy ei monos". Again, Pandekte here has Petaste with klasma on ZW flat (with yfesis) instead of NH-ZW-KE.. at the beginning. Moreover, Pandekte has a martyria of DI diatonic after "Zwns" which is another indication that we are in Agia and therefore GA natural, but sharped because of the melodic attraction (elxis).