Octoéchos

The Octoechos (of the Greek: Ὀκτώηχος, " 8 échos") is the theoretical framework in which the eight forms of Modalité S. Initialement applied to the Byzantine music are described, this framework was taken again for the description of the Plain song, more particularly the classification of the parts of the Gregorian chant.

Although the Plain song is clearly modal, its theoretical description is an open-ended question and disputed. It is probable that in the millenium that lasted the productive period of the Gregorian chant, the modal approaches could evolve/move, leading to parts of varied logic, even to rehandlings to reformulate antiquated parts within the framework of the octoéchos.

As a framework of explanation, the octoéchos belongs to the tradition of the Gregorian chant: it was introduced during the Carolingian reform of the Plain-chant. However, this theoretical framework is opposed to the simpler methods, founded on some cord-mothers ( C , semi and sometimes D ) who characterize the oldest layers of all the repertories of the Plain-chant.

Eight modes of accompaniment

Independently of any controversy, the octoéchos makes it possible to determine to it formula-type which must accompany a given part.

Certain Gregorian parts can be supplemented by standard formulas: chant supplementing the antiennes, verse of Gloria supplementing Introït or let us répons them prolix… These standard formulas of accompaniment are distributed according to eight principal modes, and each part receives the number of the " mode" standard formula which comes to accompany it.

The relation between parts and modes of accompaniment is based on a classification formal (and rather artificial) of the parts, following:

the final note of the part ( D , semi , F or ground ), after the part was suitably transposed to finish on one of these finales;
dominant content of the part, or that of the associated chant.

Identification of the content

The final depends on the part itself, but the psalmodic content is not registered there. What differentiates the even modes of the odd modes, for the same final, it is the character authente or plagal of the part.

the odd modes are the modes authente . They will pose the final note of the part far in the low register, with an interval of a fifth (or a sixth, for the third mode) compared to the theoretical psalmodic content. So their final note is normally not used like content, but has only one role of note of support. Their normal tessiture thus goes from the finale to its higher octave.
the even modes are the modes plagaux . They use the final note as lower effective content, in addition to the psalmodic content higher going up than tièrce (or with the quad for modes 4 and 8). The lower content has its own note of support, with tièrce (for the content of semi) or with the lower quad, on which it can pose its own rates. Their normal tessiture thus extends from an octave starting from this lower note of support.

This psalmodic content is normally located at tièrce or the fifth of the finale. The three modes (3, 4 and 8) which goes up to the quad and the sixth, instead of the third and the fifth of the other modes, are those of the family of the hexacorde (chants originally made on semi and if is respectively assembled to the F and with the C ).

Finale of the part

the finales in D correspond to the First mode (content on the ) and to the Second mode (content on F ).
the finales in semi correspond to the Third mode (content with the sixth on C ) and to the Fourth mode (content with the quad on the ).
the finales in F correspond to the Fifth mode (content of C ) and to the Sixth mode (content on the ).
the finales in ground correspond to the Seventh mode (content of D ) and to the Eighth mode (content with the quad of C ).

The dominant tonality of the antienne and its final result in choosing one of the eight tons whereby the psalm must be sung. This tone is generally indicated at the beginning of antienne (as well as the final). The tone of the psalm is thus not associated with the psalm itself, but is granted to the antienne. The tone retained for the psalm can have several alternatives of finales, generally indicated by their last note. The alternative is generally selected so that the last note of the psalm coincides with the first note of the antienne, or at least allows an easy musical sequence.

Formulas standard of Octoechos

The formulas which one meets according to the " eight modes" are in the Gregorian chant:

the psalmodic formulas which accompany the song by the antiennes (certain modes however have very many alternatives of finales).
psalmodic formulas particular to the song of the Magnificat.
verses which accompanies the song by the Introït (formula which also formerly accompanied the song by communion), with some alternatives of finales.
the verses of let us répons prolix.

Lastly, each tone has specific formulas of Alleluia pascals being able to be added to the antiennes of the office, with those of Introït, the offertoire, of the communion, or of let us répons prolix.

Octoechos: eight traditional modes

The classical theory wants that the Gregorian chant counts 8 modes:

Protus: finale D (third T + 1/2 T):

- > 1st mode: dominant the (ambitus D-D )

- > 2nd mode: dominant F (ambitus it )

Deutérus: finale semi (third 1/2 T + T):

- > 3rd mode: dominant C (ambitus semi-semi )

- > 4th mode: dominant the

Tritus: finale F (third (1/2 T) + T + T):

- > 5th mode: dominant C (ambitus F-F )

- > 6th mode: dominant the

Tetrardus: finale ground (third (T) + T + T):

- > 7th mode: dominant D (ambitus ground-to-ground )

- > 8th mode: dominant C

N.B. : The odd modes are acute or authentes, the even modes serious and are called plagaux.

In modern figurings, we would have

Protus and Tritus:

authente: ré/la and fa/do , dominant Ve degree
plagal: ré/fa and fa/la , dominant IIIe degree

Deutérus and Tetrardus:

authente: mi/do and sol/ré , dominant Life degree
plagal: mi/la and sol/do , dominant IVe degree

Critical of Octoechos

The advantage of this system of classification of the Gregorian parts is obvious: it makes it possible to allot to all the parts verses on melody-type of limited number (in the final analysis, ten, if one includes tons them peregrinus and in directu ). In addition, modal environments of the parts classified under the same tone are rather often similar; but there are important exceptions.

Critical technique

Its weaknesses are rather obvious compared to the Gregorian bottom:

the final of a part is given only by only one note. Many examples in the repertory show that this final was not always stable, which results in changing the class of a part as soon as its final becomes erroneous. A rather obvious example is the Introït Lex Domini , clearly of type Fifth mode, from which the finale is accidentally descended a third.
the transpositions of the parts are not always univocal. When a part can be transposed, its " mode" conventional is not given.
the content of the parts always does not return within the theoretical framework of the octoéchos: many parts of the first mode, for example, have a content with the quad ( D - ground ) which makes it possible to classify them neither in the first, nor in the second mode.

The Alléluia of the vigil of Christmas gives an good example of badly determined tonality, which modes 5,6,7 and 8 of the octoéchos could assert:

Ecrit in ground by the vaticane, it could as well be written in F , which would impose if flat, but would give better an account of the Bistrophae, more frequent on a F than on a ground . In fact, a correct writing should restore it in C , but this final is ignored by the theory of Octoéchos.
In addition, this part does nothing but comment on the modal note (transcribed here by a C ) by higher embroideries, but no content appears in these embroideries: is this a quad ( F ), a fifth ( ground )? For lack of content, it is not possible to slice between a mode plagal and a authente .

The most serious disadvantage of the octoéchos appears when this theory is used as tool for analysis of the method of the parts. This approach imposes a position a priori modal cords on parts which can be atypical, which leads to a perception deformed of the Gregorian method to make there return these particular cases at all costs. A great part of speech on dominant the multiples of the modes is probably due to this artificial approach.

Critical history

The analysis of the modes by their finale is indissociable theory pythagorician on the range and the organization of the octave. Octave and range are given a priori , and the organization of the notes in the fixed octave and its harmonic reports/ratios is used then as analysis with the melody structure. The idea to analyze each note of the Gregorian modes by its position in the octave is traditional, and present as of the introduction of the octoéchos; it still constantly is found as guides of analysis in recent works or talks on " the Gregorian method ". It however does not rest on any historical base.

This classical theory of the octave does not correspond to the context in which the concept of Teneur initially emerged: the primitive modes develop on a ambitus of a fifth or a sixth at most, and even the more elaborate modes hesitate to make play the melody over relations of octaves. It is only in the late parts of the repertory that these relations appear, probably under the influence of the Organum already present.

In addition, the modal logic of Gregorian does not individualize the notes in the same way: the primitive modes show that a note makes reference to a content, single pole of reference, and not with harmonic relations pre-established in an octave, like does it the approach pythagorician. In a coloured way, one can say that the logic of composition of the Plain-chant is that of an air of bagpipe, whereas that of the range pythagorician is thought as accompanied by the quadrant by Orphée.

Bonds

Gregorian modes. Dom Daniel Saulnier, Solesmes 1997.

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