Page:A Dictionary of Music and Musicians vol 2.djvu/773

PLAGAL MODES.

The number of the Modes being thus increased to eight, a new form of nomenclature was naturally demanded for them, while a new system of numbering became still more imperatively necessary. The change of nomenclature was easily arranged. In order to prevent unnecessary confusion, the old names Dorian, Phrygian, Lydian, and Mixolydian, were still retained for the Authentic Modes, while the Plagal forms were distinguished from them by the addition of the prefix Hypo (under), the new Scales being called the Hypodorian, Hypophrygian, Hypolydian, and Hypomixolydian, Modes. On the other hand, it was indispensable that the numbers of the Modes should be entirely changed; the Phrygian becoming the Third Mode, instead of the Second; the Lydian, the Fifth; and the Mixolydian, the Seventh: the Second, Fourth, Sixth, and Eighth places, being reserved for the newer Plagal forms.

The next great change was the introduction of two new Authentic Modes, called the Æolian, and the Ionian, having A and C for their Finals, and naturally giving rise to two new Plagal forms, entitled the Hypoæolian, and Hypoionian, and lying between E and E, and G and G, respectively.

The precise time at which these new Modes were brought into general use cannot be ascertained; but we hear of them, with certainty, as early as the reign of Charlemagne (ob. 814) though the earliest exhaustive account of the entire system bequeathed to us is that contained in the ../Dodecachordon/ of Glareanus, published in 1529. The learned author of this invaluable work insists strongly upon the use of twelve distinct tonalities, and prefaces his volume with a list of them, divided into two parallel columns, he first of which contains the Plagal, and the second the Authentic Modes, arranged in their natural order, the series being supplemented by rhe rejected Hyperæolian Mode, having B for its Final, and its Plagal derivative, the Hyperphrygian, with the necessary caution, sed est error.

The completion of the Gregorian system by the addition of the Æolian and Ionian Modes, with their respective Plagals, was productive of very important results, and enriched the series with the capability of introducing a far greater amount of varied expression than is apparent at first sight. Some writers have objected to them, on the ground that they are in reality no more than unnecessary reduplications of already existing Scales, since, in its compass, and the disposition of its Semitones, the Æolian Mode corresponds exactly with the Hypodorian, the Hypoæolian with the Phrygian, the Ionian with the Hypolydian, and the Hypoionian with the Mixolydian. By parity of reasoning, the Hypomixolydian Mode should also be regarded as superfluous, since its compass, and Semitones, correspond precisely with those of the Dorian. But a little consideration will prove this argument to be utterly fallacious. In all that concerns expression, the Eighth Mode differs, toto cœlo, from the First; for its Final—the note to which the ear is constantly attracted—lies in the middle of its series of sounds, whereas, in the Dorian Mode, it occupies the lowest place. This peculiarity invests all the Plagal Modes, without exception, with a character entirely different from that which distinguishes the Authentic series; a fact which was so well known to the earlier writers on the subject that they assigned to each Mode a special epithet descriptive of its æsthetic peculiarities, Thus, the First Mode was called 'Modus Gravis,' the Second, 'Modus Tristis,' the Third, 'Modus Mysticus,' the Fourth, 'Modus Harmonious,' the Fifth, 'Modus Lætus,' the Sixth, Modus Devotus,' the Seventh, 'Modus Angelicus,' and the Eighth, 'Modus Perfectus.' On carefully examining this classification, we shall find that the Plagal Modes are everywhere characterised by a calmer and less decided force of expression than their authentic originals; thus, while the latter are described as Grave, Mystical, Joyful, and Angelic, the former are merely Sad, Harmonious, Devout, and Perfect. The solemn grandeur of the First