# 1911 Encyclopædia Britannica/Plain Song

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​PLAIN SONG, or Plain Chant (Gregorian Music; Lat. cantus planus; Ital. canto gregoriano; Fr. plain chant), a style of unisonous music, easily recognizable by certain strongly marked characteristics, some very ancient fragments of which are believed to have been in use under the Jewish dispensation from a remote period, and to have been thence transferred to the ritual of the Christian Church.
The theories advanced as to the origin of this solemn form of ecclesiastical music are innumerable. The most widely spread opinion is that the older portion of it originated with the Psalms themselves, or at least sprang from the later synagogue music. Another theory traces the origin of plain song to the early Greeks; and the supporters of this view lay much stress on the fact that the scales in which its melodies are composed are named after the old Greek “modes.” But, beyond the name, no connexion whatever exists between the two tonalities. Less reasonable hypotheses attribute the origin of the plain song to the Phoenicians, to the Egyptians, to the early Christian converts, and to the musicians of the middle ages.
​Towards the close of the 4th century Ambrose of Milan, fearing the loss or corruption of the venerable melodies which had been preserved by means of oral tradition only, endeavoured to restore them to their primitive purity, and to teach the clergy to sing them with greater precision. A still more extensive work of the same nature was undertaken, two centuries later, by Pope Gregory the Great. And thus arose two schools of ecclesiastical music, still known as the “ Ambrosian ” and the “ Gregorian chant ”-the first of which is practised only in the diocese of Milan, while the latter is Lmiversally accepted as the authorized “ Roman use.” In order to explain the essential differences between these two schools, we must describe in detail some of the peculiar characteristics of plain song. The melodies which form the réperloire of plain chant are not written in modern major and minor scales, but in certain tonalities bearing names analogous to those of the early Greek “modes/' though constructed on very different principles. Of these “ modes, ” fourteen exist in theory, though twelve only are in practical use. The intervals of each “ mode ” are derived from a fundamental sound, called its “ final.” 1 The compass of each mode comprises eight sounds- that of the first, third, lifth, seventh, ninth, eleventh and thirteenth “ modes ” extending to the octave above the “ final, ” and that of the second, fourth, sixth, eighth, tenth, twelfth and fourteenth extending from the fourth note below the final to the fifth note above it. Consequently, the “ fmals ” of the first series, called the “ authentic modes, ” occupy the lowest place in each system of sounds, and those of the second series, called the “ plagal modes, ” the middle place-the same “ final ” being common to one “authentic ” and one “ plagal mode.” The following table exhibits the entire system, expressed in the alphabetical notation peculiar to modern English music-the “ final ” being indicated in each case by an asterisk, and the position of the semitones, from which each mode derives its distinctive character, by brackets. Authenisc Modes Plagal Modes.
x Dorian, *D, E, F, G, A, B. C, D. 2. Hypodorian, A, B C, *D, E, F, G, A/- /- /- /-
3 Phrygian, *E, F G, /Q* B, CQ E. 4
5 Lydian, *F, G, A, E C, D, E F 6
7 Mixolyd|an, *G, A B, C, D, E, F, G 8
Hypophrygia.n, B, C, D, *E, F, G.A, B
Hypolydnan, C, D, IL, *F, G, A, B, C
Hypomixolydian, D, E, F, *G, A B, C, D
9 Aeohan, *A. B, C, D, E, F, G, A. xo Hypoaeollan, E, F G, *; kB, C;l)<E /-
II Locnan, *B< E>2, E, F, § JA, B. iz. Hypoloorun, F, G, A, *B, C, D/§ <F, I3 Ionian, #c, D, E, F, G, A, B, c. 14 Hypoionnm, G, A, BT-QI, D, ra, F, c Nos 11 and 12 in this series are
into which we have not space to enter; they are practically useless! Of these modes Ambrose used four only-the first four “authentic modes, ” now numbered I, 3, 5 and 7. Gregory acknowledged, and is said by some historians of credit to have invented, the first four “ plagal modes ”-Nos. 2, 4, 6 and 8. The use of the remaining “ modes, ” except perhaps the ninth, was not formally authorized until the reign of Charlemagne, who published an official decision upon the subject. In one or other of the twelve “ modes ” recognized by this decision every plain-chant melody is composed. The number of such melodies preserved to us, the genuineness of which is undoubted, is very large; and the collection is divided into several distinct classes, the most important of which are the melodies proper to the Psalm- Tones and Antiphonv; the Ordina/rium M issae, the I nlroits, Graduals and Ojerloria; the Praefaliones, Versiculi and Responsoria; the H ymm and Sequences; and the Lamentalzones, Exullet and other music used in Holy Week.
Of these classes the most interesting by far is that which includes the psalm-tones, or psalm-tunes, called by modern English historians, the “ Gregorian tones.” The oldest of these are tones 1, 3, 5 and 7, as sung by Ambrose. The antiquity of tones 2, 4, 6 and 8 is less firmly established, though there is no doubt that Gregory the Great sanctioned their use on strong traditional evidence. In addition to these, a peculiarly beautiful melody in mode 9, known as the Tonus peregrin/us, has been sung from time immemorial only to the psalm In exitu Israel. Analogous to the tonic or key-note of the modern scale. For fuller information on the subject see the article “ Modes, " in Grove's Dictionary of Music.
rejected, for technical reasons
The oldest version of this melody now extant is undoubtedly to a certain extent impure; but tradition imputes to it a veryhigh antiquity, and even our doubts as to the authenticity of the now generally accepted reading extend only to one single note. A widely accepted tradition points out this melody as the tune sung to In exitu Israel, as part of the Great Hallel (see PSALMS), which is generally (but hardly rightly) identified with the hymn sung by Christ and His apostles immediately after the Last Supper.
One very powerful argument in favour of the Jewish origin of the psalm-tones lies in the peculiarity of their construction. It is impossible to ignore the perfect adaptation of these venerable melodies to the laws of Hebrew poetry, as opposed to those which governed Greek and Latin verse. The division of the tune into two distinct strains, exactly balancing each other, points assuredly to the intention of singing it to the two contrasted phrases which, inseparable from the constitution of a Hebrew verse, find no place in any later form of poetry. And it is very remarkable that this constructional peculiarity was never imitated, either in the earliest hymns or antiphons we possess or in those of the middle ages-evidently because it was found impossible to adapt it to any medieval form of verse-even to the Te Deum, which, though a manifest reproduction of the Hebrew psalm, was adapted by Ambrose to a melody of very different formation, and naturally so since so many of its phrases consist of a single clause only, balanced in the following verse. This peculiarity now passes for the most part unnoticed; and the Te Deum is constantly sung to a psalm-tone, very much to the detriment of both. But in the middle ages this abuse was unknown; and so it came to pass that, until the “ School of the Restoration ” gave birth, in England, to the single chant, avowedly built upon the lines of its Gregorian predecessor, and a somewhat later period to the double one, so constructed as to weld two verses of the psalm into one, often with utter disregard to the sense of the words, the venerable psalm-tones stood quite alone-the only melodies in existence to which the psalms could be chanted. And so intimate is the adaptation of these plainchant melodies to the rhythm as well as to the sense of the sacred text, even after its translation into more modern languages, so strongly do they swing with the one and emphasize the other, that it is difficult to believe that the composition of the music was not coeval with that of the poetry.
Next in antiquity to the psalm-tones are the melodies adapted to the antiphons, the oiiertoria, the graduals and the introits, sung at High Mass. Those proper to the Ordinarium missae are probably of later date. Those belonging to hymns and sequences are of all ages. Among the latest we possess-perhaps the very latest of any great importance-is that of Lauda Sion, a very ine one, in modes 7 and 8, adapted to the celebrated sequence written by Thomas Aquinas about 1261.
To the melodies adapted to the Lamenlationes and the Exullel, as sung in the Church of Rome during Holy Week, it is absolutely impossible to assign any date at all. All we know is that they are of extreme antiquity, and beautiful beyond all description. The melody of Exultet is, indeed, very frequently cited as the finest example of plain song in existence. To assert that melodies so old as these have been handed down to us in their original purity would be absurd. But the presence of corruption rarely passes undetected by the initiated; and vigorous efforts have been made from time to time to purify the received text by reference to the oldest and most trustworthy MSS. attainable. Such an eHort was begun on a very extensive scale by the “Congregation of Rites, ” at the instigation of Pope Pius IX., in the year 1868; and the labours of that learned body, together with those of the monks of Solesmes and elsewhere, have done much towards the restoration of plain chant to the highest state of purity possible. In England the Plain-Song and Medieval Music Society, founded in 1888, has also done valuable work by its publications. (W. S. R.)