PLAIN SONG 169 no connexion whatever exists between the two tonalities, which bear not the remotest resemblance to each other. Less reasonable hypotheses attribute the origin of plain song to the Phoenicians, to the Egyptians, to the early Christian converts, and to the musicians of the Middle Ages. These divergent views, however, though entirely hypothetical, are defended by arguments so voluminous that for the elucidation of the subject we must con tent ourselves with referring the reader to the works of Gerbert, P. Martini, P. Kircher, Mersennus, P. Larnbil- lotte, the Abbe Kaillard, Coussemaker, Kiesewetter, Jakob, Ambros, and other authors, who have treated it at great length. The earliest important fact upon which we can rest with absolute confidence is that towards the close of the 4th century Ambrose of Milan, fearing the loss or corruption of the venerable melodies which up to that time had been preserved to the church by means of oral tradition only, endeavoured to restore them as nearly as possible to their primitive purity, and at the same time to teach the clergy to sing them with greater precision than had pre viously been attempted. 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 now practised only in the diocese of Milan, while the latter is universally accepted as the authorized "lloman use." In order to explain the essential differences existing between these two schools, we must here describe in detail some of the peculiar characteristics of plain song to which allusion has been made. The melodies which collectively form the repertoire 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 theoC " modes," fourteen exist in theory, though twelve only are in practical use. The intervals of each " mode " are derived from a funda mental sound, called its " final." l The compass of each mode comprises eight sounds, that of the first, third, fifth, 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 "finals" 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. Authentic Modes. 1. Dorian, "D, V^Y, G, A, li^C, D. . !. Phrygian, ~E^F, G, A, B^C, D, E. 5. Lydian, *F, G, A, B^C, D, E^t 7. Mixolydian, G, A, life, U, iC^, G - . jE-jlian, A, liTc, D, E^K, G, A. 11. Locriau, *B,C, D, E~F, 0, A, B. 13. Ionian, "C, I), E^F, G, A, i^C. Plagal Modes, 2. Hypodomn, A, uTc, *D, E^V, G, A. 4. Hypophrygian, B"7c, D, *O ,G, A, B. 6. Hypolydian, C, D, E^F, G, A, fiTc. 8. Hypomixolydian,D,E7F,*Q,A,B^C,D. 10. IlypoKOlian, E, F, G, X A, iCc, D, E. 12. Hypolocrian, F, G, A, f I^~C , D, E,~t 14. Hypoionian, G, A, B/C, D, O, G - Xos. 11 and 12 in this series are rejected, for technical reasons into which we have not space to enter; they are practically useless 2 Of these modes Ambrose used four only the first four "authentic modes," now numbered 1, 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 per haps 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 immensely large ; and the collection is divided into several distinct classes, the most important of which are the melodies proper to the Psalm-Tones and Antip/ions ; the Ordinarium Missx , the Introits, Graduals, and Offertoria ; the I rxfationes, Versiculi, and fiesponsoria ; the Hymns and Sequences ; and the Lamentationes, ExulM, 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 tradi tional evidence. In addition to these, a peculiarly beauti ful melody in mode 9, known as the Tonus peregrinus, has been sung from time immemorial only to the psalm In cj:itu Israd. The oldest version of this melody now extant is undoubtedly to a certain extent impure ; but tradition imputes to it a very high 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 our Lord and His apostles immediately after the institution of the Last Supper. One very powerful argument in favour of the Jewish origin of the psalm-tones lies in the peculiarity of their construction. We are not aware that this argument has ever been previously brought forward ; but it is im possible to subject the venerable melodies to minute examination without observing their perfect adaptation to the laws of Hebrew poetry, as opposed to those which governed Greek and Latin verse. The division of the tune in every case, without exception, 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 medi aeval 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 peculi arity now passes for the most part unnoticed ; and the Tt 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 Kestoration " gave birth, in England, to the single chant, avowedly built upon the lines ol 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 onlv melodies in existence to which the psalms could
XIX. 22