Editing Gregorian chant (section)

==Musical form==

===Melodic types===
Gregorian chant is, as 'chant' implies, vocal music. The text, the phrases, words and eventually the syllables, can be sung in various ways. The most straightforward is recitation on the same tone, which is called "syllabic" as each syllable is sung to a single tone. Likewise, simple chants are often syllabic throughout with only a few instances where two or more notes are sung on one syllable. "Neumatic" chants are more embellished and [[ligature (music)|ligatures]], a connected group of notes, written as a single compound neume, abound in the text. [[Melisma]]tic chants are the most ornate chants in which elaborate melodies are sung on long sustained vowels as in the Alleluia, ranging from five or six notes per syllable to over sixty in the more prolix melismata.{{sfn|Hoppin|1978a|pp=85–88}}

{{Listen|type=music|filename=Epistle for the Solemn Mass of Easter Day.ogg|title=Epistle for the Solemn Mass of Easter Day|description=Example of liturgical recitative in Gregorian chant}}
Gregorian chants fall into two broad categories of melody: [[recitative]]s and free melodies.{{sfn|Apel|1990|p=203}} The simplest kind of melody is the liturgical recitative. Recitative melodies are dominated by a single pitch, called the ''[[reciting tone]]''. Other pitches appear in melodic formulae for [[incipit]]s, partial [[cadence]]s, and full cadences. These chants are primarily syllabic. For example, the [[Collect]] for [[Easter]] consists of 127 syllables sung to 131 pitches, with 108 of these pitches being the reciting note A and the other 23 pitches flexing down to G.{{sfn|Hoppin|1978b|p=11}} Liturgical recitatives are commonly found in the [[Accentus Ecclesiasticus|accentus]] chants of the liturgy, such as the intonations of the Collect, [[Epistle]], and [[Gospel]] during the [[Mass (liturgy)|Mass]], and in the direct [[psalmody]] of the [[Canonical hours|Office]].

Psalmodic chants, which intone [[psalms]], include both recitatives and free melodies. Psalmodic chants include ''direct psalmody'', ''antiphonal chants'', and ''responsorial chants''.{{sfn|Hoppin|1978a|p=81}} In direct psalmody, psalm verses are sung without refrains to simple, formulaic tones. Most psalmodic chants are antiphonal and responsorial, sung to free melodies of varying complexity.

[[File:Evora06.jpg|thumb|Antiphonary with Gregorian chants]]
{{Listen|type=music|filename=Loquetur Dominus.ogg|title=''Loquetur Dominus'', Introit for Week XXXIV of Ordinary Time|description=Example of antiphonal psalmody in Gregorian chant
|filename2=De profundis.ogg|title2=''De profundis'', tract for the Requiem Mass|description2=Example of responsorial psalmody in Gregorian chant}}
Antiphonal chants such as the [[Introit]], and [[Communion (chant)|Communion]] originally referred to chants in which two choirs sang in alternation, one choir singing verses of a psalm, the other singing a refrain called an ''[[antiphon]]''. Over time, the verses were reduced in number, usually to just one psalm verse and the [[doxology]], or even omitted entirely. Antiphonal chants reflect their ancient origins as elaborate recitatives through the reciting tones in their melodies. Ordinary chants, such as the [[Kyrie]] and [[Gloria in Excelsis Deo|Gloria]], are not considered antiphonal chants, although they are often performed in antiphonal style.

Responsorial chants such as the [[Gradual]], [[Alleluia]], [[Offertory]], and the Office Responsories originally consisted of a refrain called a ''respond'' sung by a choir, alternating with psalm verses sung by a soloist. [[Responsory|Responsorial]] chants are often composed of an amalgamation of various stock musical phrases, pieced together in a practice called ''[[centonization]]''. Tracts are melismatic settings of psalm verses and use frequent recurring cadences and they are strongly centonized.

Gregorian chant evolved to fulfill various functions in the Roman Catholic liturgy. Broadly speaking, liturgical recitatives are used for texts intoned by deacons or priests. Antiphonal chants accompany liturgical actions: the entrance of the officiant, the collection of offerings, and the distribution of the Eucharist. Responsorial chants expand on readings and lessons.{{sfn|Hoppin|1978a|p=123}}

The non-psalmodic chants, including the [[Ordinary of the Mass]], [[Sequence (poetry)|sequences]], and [[hymn]]s, were originally intended for congregational singing.{{sfn|Hoppin|1978a|p=131}} The structure of their texts largely defines their musical style. In sequences, the same melodic phrase is repeated in each couplet. The strophic texts of hymns use the same syllabic melody for each stanza.

===Modality===
{{Main|Mode (music)}}
Early plainchant, like much of Western music, is believed to have been distinguished by the use of the [[diatonic scale]]. Modal theory, which postdates the composition of the core chant repertory, arises from a synthesis of two very different traditions: the speculative tradition of numerical ratios and species inherited from ancient Greece and a second tradition rooted in the practical art of cantus. The earliest writings that deal with both theory and practice include the [[Musica enchiriadis|Enchiriadis]] group of treatises, which circulated in the late ninth century and possibly have their roots in an earlier, oral tradition. In contrast to the ancient Greek system of tetrachords (a collection of four continuous notes) that descend by two tones and a semitone, the Enchiriadis writings base their tone-system on a tetrachord that corresponds to the four finals of chant, D, E, F, and G. The disjunct tetrachords in the Enchiriadis system have been the subject of much speculation, because they do not correspond to the diatonic framework that became the standard Medieval scale (for example, there is a high F{{music|#}}, a note not recognized by later Medieval writers). A diatonic scale with a chromatically alterable b/b-flat was first described by [[Hucbald]], who adopted the tetrachord of the finals (D, E, F, G) and constructed the rest of the system following the model of the Greek Greater and Lesser Perfect Systems. These were the first steps in forging a theoretical tradition that corresponded to chant.

Around 1025, [[Guido d'Arezzo]] revolutionized Western music with the development of the ''gamut'', in which pitches in the singing range were organized into overlapping [[hexachord]]s. Hexachords could be built on C (the natural hexachord, C-D-E^F-G-A), F (the soft hexachord, using a B-flat, F-G-A^B{{music|b}}-C-D), or G (the hard hexachord, using a B-natural, G-A-B^C-D-E). The B-flat was an integral part of the system of hexachords rather than an [[accidental (music)|accidental]]. The use of notes outside of this collection was described as [[musica ficta]].

Gregorian chant was categorized into eight [[mode (music)|modes]], influenced by the eightfold division of [[Byzantine chant]]s called the ''[[oktoechos]]''.{{sfn|Wilson|1990|p=11}} Each mode is distinguished by its ''final'', ''dominant'', and ''ambitus''. The ''final'' is the ending note, which is usually an important note in the overall structure of the melody. The ''dominant'' is a secondary pitch that usually serves as a [[reciting tone]] in the melody. ''[[Ambitus (music)|Ambitus]]'' refers to the range of pitches used in the melody. Melodies whose final is in the middle of the ambitus, or which have only a limited ambitus, are categorized as ''plagal'', while melodies whose final is in the lower end of the ambitus and have a range of over five or six notes are categorized as ''authentic''. Although corresponding plagal and authentic modes have the same final, they have different dominants.{{sfn|Hoppin|1978a|pp=64–65}} The existent pseudo-Greek names of the modes, rarely used in medieval times, derive from a misunderstanding of the Ancient Greek modes; the prefix "[[wikt:hypo-|hypo-]]" (under, Gr.) indicates a plagal mode, where the melody moves below the final. In contemporary Latin manuscripts the modes are simply called Protus authentus /plagalis, Deuterus, Tritus and Tetrardus: the 1st mode, authentic or plagal, the 2nd mode etc. In the Roman Chantbooks the modes are indicated by Roman numerals.

:Modes 1 and 2 are the authentic and plagal modes ending on D, sometimes called [[Dorian mode|Dorian]] and [[Hypodorian mode|Hypodorian]].
:Modes 3 and 4 are the authentic and plagal modes ending on E, sometimes called [[Phrygian mode|Phrygian]] and [[Hypophrygian mode|Hypophrygian]].
:Modes 5 and 6 are the authentic and plagal modes ending on F, sometimes called [[Lydian mode|Lydian]] and [[Hypolydian mode|Hypolydian]].
:Modes 7 and 8 are the authentic and plagal modes ending on G, sometimes called [[Mixolydian mode|Mixolydian]] and [[Hypomixolydian mode|Hypomixolydian]].

Although the modes with melodies ending on A, B, and C are sometimes referred to as [[Aeolian mode|Aeolian]], [[Locrian mode|Locrian]], and [[Ionian mode|Ionian]], these are not considered distinct modes and are treated as [[Transposition (music)|transpositions]] of whichever mode uses the same set of hexachords. The actual pitch of the Gregorian chant is not fixed, so the piece can be sung in whichever range is most comfortable.

Certain classes of Gregorian chant have a separate musical formula for each mode, allowing one section of the chant to transition smoothly into the next section, such as the psalm verses that are sung between the repetition of antiphons, or the Gloria Patri. Thus we find models for the recitation of psalmverses, Alleluia and Gloria Patri for all eight modes.{{sfn|Hoppin|1978a|p=82}}

Not every Gregorian chant fits neatly into Guido's hexachords or into the system of eight modes. For example, there are chants – especially from German sources – whose [[neume]]s suggest a warbling of pitches between the notes E and F, outside the hexachord system, or in other words, employing a form of [[chromaticism]].{{sfn|Wilson|1990|p=22}} Early Gregorian chant, like Ambrosian and Old Roman chant, whose melodies are most closely related to Gregorian, did not use the modal system.{{sfn|Apel|1990|pp=166–178}}{{sfn|Hiley|1995|p=454}} The great need for a system of organizing chants lies in the need to link antiphons with standard tones, as in for example, the psalmody at the Office. Using Psalm Tone i with an antiphon in Mode 1 makes for a smooth transition between the end of the antiphon and the intonation of the tone, and the ending of the tone can then be chosen to provide a smooth transition back to the antiphon. As the modal system gained acceptance, Gregorian chants were edited to conform to the modes, especially during 12th-century [[Cistercian]] reforms. Finals were altered, melodic ranges reduced, melismata trimmed, B-flats eliminated, and repeated words removed.{{sfn|Hiley|1995|pp=608–610}} Despite these attempts to impose modal consistency, some chants – notably Communions – defy simple modal assignment. For example, in four medieval manuscripts, the Communion ''Circuibo'' was transcribed using a different mode in each.{{sfn|Apel|1990|pp=171–172}}

===Musical idiom===
Several features besides modality contribute to the musical idiom of Gregorian chant, giving it a distinctive musical flavor. Melodic motion is primarily [[steps and skips|stepwise]]. Skips of a third are common, and larger skips far more common than in other plainchant repertories such as Ambrosian chant or Beneventan chant. Gregorian melodies are more likely to traverse a seventh than a full octave, so that melodies rarely travel from D up to the D an octave higher, but often travel from D to the C a seventh higher, using such patterns as D-F-G-A-C.{{sfn|Apel|1990|pp=256–257}}> Gregorian melodies often explore chains of pitches, such as F-A-C, around which the other notes of the chant gravitate.{{sfn|Wilson|1990|p=21}} Within each mode, certain incipits and cadences are preferred, which the modal theory alone does not explain. Chants often display complex internal structures that combine and repeat musical subphrases. This occurs notably in the [[Offertory|Offertories]]; in chants with shorter, repeating texts such as the [[Kyrie]] and [[Agnus Dei (music)|Agnus Dei]]; and in longer chants with clear textual divisions such as the Great Responsories, the [[Gloria in excelsis Deo|Gloria]], and the [[Credo]].{{sfn|Apel|1990|pp=258–259}}

Chants sometimes fall into melodically related groups. The musical phrases [[centonization|centonized]] to create [[Gradual]]s and [[Tract (liturgy)|Tracts]] follow a musical "grammar" of sorts. Certain phrases are used only at the beginnings of chants, or only at the end, or only in certain combinations, creating musical families of chants such as the ''[[Iustus ut palma]]'' family of Graduals.{{sfn|Apel|1990|pp=344–363}} Several [[Introit]]s in mode 3, including ''Loquetur Dominus'' above, exhibit melodic similarities. Mode III (E authentic) chants have C as a dominant, so C is the expected reciting tone. These mode III Introits, however, use both G and C as reciting tones, and often begin with a decorated leap from G to C to establish this tonality.{{sfn|Hiley|1995|pp=110–113}} Similar examples exist throughout the repertory.

===Notation===
[[File:Neume2.jpg|thumb|Offertory ''Iubilate deo universa terra'' in unheightened neume]]{{Main|Neume}}
The earliest notated sources of Gregorian chant (written {{Circa|950|lk=no}}) used symbols called ''[[neume]]s'' (Gr. sign, of the hand) to indicate tone-movements and relative duration within each syllable. A sort of musical stenography that seems to focus on gestures and tone-movements but not the specific pitches of individual notes, nor the relative starting pitches of each neume. Given the fact that Chant was learned in an oral tradition in which the texts and melodies were sung from memory, this was obviously not necessary. The neumatic manuscripts display great sophistication and precision in notation and a wealth of graphic signs to indicate the musical gesture and proper pronunciation of the text.
Scholars postulate that this practice may have been derived from [[cheironomy|cheironomic]] hand-gestures, the [[ekphonetic]] notation of [[Byzantine chant]], punctuation marks, or diacritical accents.{{sfn|Levy|Emerson|Bellingham|Hiley<!-- |Zon -->|2001|loc=§6.1}} Later adaptations and innovations included the use of a dry-scratched line or an inked line or two lines, marked C or F showing the relative pitches between neumes. Consistent relative heightening first developed in the Aquitaine region, particularly at [[Saint Martial|St. Martial de Limoges]], in the first half of the eleventh century. Many German-speaking areas, however, continued to use unpitched neumes into the twelfth century. Additional symbols developed, such as the ''custos'', placed at the end of a system to show the next pitch. Other symbols indicated changes in articulation, duration, or tempo, such as a letter "t" to indicate a [[tenuto]]. Another form of early notation used a system of letters corresponding to different pitches, much as [[Shaker music]] is notated.

[[File:gregorian chant.gif|frame|''[[Liber usualis]]'' in square notation (excerpt from the ''Kyrie eleison (Orbis factor)'')]]
By the 13th century, the neumes of Gregorian chant were usually written in ''square notation'' on a four-line staff with a clef, as in the ''Graduale Aboense'' pictured above. In square notation, small groups of ascending notes on a syllable are shown as stacked squares, read from bottom to top, while descending notes are written with diamonds read from left to right. When a syllable has a large number of notes, a series of smaller such groups of neumes are written in succession, read from left to right. The [[oriscus]], [[quilisma]], and [[liquescent]] neumes indicate special vocal treatments, that have been largely neglected due to uncertainty as to how to sing them. Since the 1970s, with the influential insights of Dom {{ill|Eugène Cardine|fr}} (see below under 'rhythm'), ornamental neumes have received more attention from both researchers and performers.
B-flat is indicated by a "b-mollum" (Lat. soft), a rounded undercaste 'b' placed to the left of the entire neume in which the note occurs, as shown in the "Kyrie" to the right. When necessary, a "b-durum" (Lat. hard), written squarely, indicates B-natural and serves to cancel the b-mollum. This system of square notation is standard in modern chantbooks.