. In so far as the mensural system of notation was graphic, in that the position of the notes in the scale presented accurately the direction of the changing pitch of the sounds they stood for, there was no need of preserving in the ligatures such peculiarities of the neumatic signs. But, on the other hand, these peculiarities were needed to represent the mensural value of the notes in the ligatures, the more so because the mensuralists were determined to allow no freedom in the rendering of those ornaments in ligature, but rather to reduce each one to an exact numerical value. Hence we find two kinds of ligatures: those which preserved the traits inherited from their neumatic ancestors, and those in which such marks were lacking. The first were very properly called cum proprietate, the others sine proprietate; and the rule was that in every ligature cum proprietate the first note was a breve, while in every ligature sine proprietate it was a long. If the ligature represented a series of breves and semi-breves, the preliminary stroke was upward from the note, not to it, thus:
.
Further than this we need not go in our explanation of notation according to the mensural system. The mensuralists had their way and reduced all music to a purely arbitrary system of triple proportion, and their notation, though bewildering and complex, was practically without flaw. The reaction from it will be treated in the next chapter. Meanwhile we have to consider what forms of music developed under this new method.
V
Regarding the relations of the voice parts, one is struck by the new attitude toward consonance and dissonance of which they give proof. In the old and in the free organum only four intervals were admitted as consonant—the unison, the fourth, the fifth, and the octave. The third and the sixth, which add so much color to our harmony, were appreciated and considered pleasant only just before the final unison or octave. The mensuralists admitted them as consonant, though they qualified them as imperfect. For, true to the time in which they lived, they divided the consonants theoretically into classes—the octave and unison being defined as perfect, the fourth and the fifth as intermediate, the third and later the sixth as imperfect. So far did the love of system carry them that, feeling the need of a balancing theory of dissonances, these were divided into three classes similarly defined as perfect, intermediate, and imperfect. We should, indeed, be hard put to-day to discriminate between a perfect and an imperfect discord. Of the imperfect consonances the thirds were first to be recognized, the minor third being preferred, as less imperfect, to the major. The major sixth came next and the last to be consecrated was the minor sixth, which, for some years after the major had been admitted among the tolerably pleasant concords, was held to be intolerably dissonant. The fact that these concords, now held to be the richest and most satisfying in music, were then called imperfect is striking proof of the perseverance of the old classical ideas of concord and discord inherited from the Greeks. Again, one must suspect that theory and practice do not walk hand in hand through the history of music in the Middle Ages.
The admission of thirds and sixths even grudgingly among the consonant intervals is proof that through some common or popular practice of singing they had become familiar and pleasant to the ears of men. We have already mentioned the possible origin of organum in the practice of improvising counter-melodies which seems to have existed among the Celts and Germans of Europe at a very early age. There is some reason to believe that in this practice thirds and sixths played an important rôle; in fact, that there were two kinds of organizing or descant, one of which, called gymel, consisted wholly of thirds, the other, called faux-bourdon, of thirds and sixths. These kinds of organizing, it is true, are not mentioned by name until nearly the close of the fourteenth century, but there is evidence that they were of ancient origin. Whether or not these were the popular practices which brought the agreeable nature of thirds and sixths to the attention of the mensuralists has not yet been definitely determined. The reader is referred to Dr. Riemann’s Geschichte der Musiktheorie im IX-XIV Jahrhundert (Leipzig, 1898), and the ‘Oxford History of Music,’ Vol. I, by H. E. Wooldridge (Part I, p. 160), for discussions on both sides of the question. The word gymel was derived from the Latin gemellus, meaning twin, and the cantus gemellus, or organizing in thirds, in fact, consists of twin melodies. Faux-bourdon means false burden, or bass. The term was applied to the practice of singers who sang the lowest part of a piece of music an octave higher than it was actually written. If the chord C-E-G is so sung then it becomes E-G-C, and whereas in the original chord as written the intervals are the third, from C to E, and the fifth, from C to G, in the transposed form the intervals are the third, from E to G, and the sixth, from E to C, of which intervals faux-bourdon consisted. The origin of this ‘false singing’ offered by Mr. Wooldridge,[68] though properly belonging in a later period, may be summarized here.
By the first quarter of the fourteenth century the methods of descant had become thoroughly obnoxious to the ecclesiastical authorities and the Pope, John XXII, issued a decree in 1322 for the restriction of descant and for the reëstablishing of plain-song. The old parallel organum of the fifth and fourth was still allowed. Singers, chafing under the severe restraint, added a third part between the cantus firmus and the fifth which on the written page looked innocent enough to escape detection, and further enriched the effect of their singing by transposing their plain-song to the octave above, which, as we have seen, then moved in the pleasant relation of the sixth to the written middle part. Thus, though the written parts looked in the book sufficiently like the old parallel organum, the effect of the singing was totally different. However, this explanation of the origin of the term faux-bourdon leaves us still unenlightened as to how the sixth had come to sound so agreeably to the ears of these rebellious singers.
Having perfected a system of notation, and having admitted the intervals pleasantest to our ears among the consonances to be allowed, having thus broadly widened their technique and the possibilities of music, we might well expect pleasing results from the mensuralists. But their music is, as a matter of fact, for the most part rigid and harsh. Several new forms of composition had been invented and had been perfected, notably by the two great organists of Notre Dame in Paris, Leo or Leonin, and his successor, Perotin. It is customary to group these compositions under three headings, namely, compositions in which all parts have the same words, compositions in which not all parts have words, and compositions in which the parts have different words. Among the first the cantilena (chanson), the rondel and rota are best understood, though the distinction between the cantilena and the rondel is not evident. The rondel was a piece in which each voice sang a part of the same melody in turn, all singing together; but, whereas in the rota one voice began alone and the others entered each after the other with the same melody at stated intervals, until all were singing together, in the rondel all voices began together, each singing its own melody, which was, in turn, exchanged for that of the others. Among the compositions of the second class (in which not all parts have words), the conductus and the organum purum were most in favor. Both are but vaguely understood. The organum purum, evidently the survival of the old free descant, was written for two, three, or even four voices. The tenor sang the tones of a plain-song melody in very long notes, while the other voices sang florid melodies above it, merely to vocalizing syllables. The conductus differed from this mainly in that such passages of florid descant over extended syllables of the plain-song were interspersed with passages in which the plain-song moved naturally in metrical rhythm, and in which the descant accompanied it note for note. In the conductus composers made use of all the devices of imitation and sequence which were at their command. Finally, the third class of compositions named above is represented by the Motet.
The Motet is by far the most remarkable of all forms invented by the mensuralists. In the first place, a melody, usually some bit of plain-song, was written down in a definite rhythmical formula. There were several of these formulæ, called ordines, at the service of the composers. The tenor part was made up of the repetition of this short formal phrase. Over this two descanting parts were set, which might be original with the composer, but which later were almost invariably two songs, preferably secular songs. These two songs were simply forced into rhythmical conformity to the tenor. They were slightly modified so as to come into consonance with each other and with the tenor at the beginning and end of the lines. Apart from this they were in no way related, either to each other or to the tenor. So came about the remarkable series of compositions in which three distinct songs, never intended to go together, are bound fast to each other by the rules of measured music, in which the tenor drones a nonsense syllable, while the descant and the treble may be singing, the one the praises of the Virgin, the other the praises of good wine in Paris. This is surely the triumphant non plus ultra of the mensuralists. Here, indeed, the rules of measured music preside in iron sway. Not only have the old free ornaments of the early church music been rigorously cramped to a formula and all the kinds of metre reduced to a stiff rule of triple perfection, but the quaint old hymns of the church have been crushed with the gay, mad songs of Paris down hard upon a droning, inexorable tenor which, like a fettered convict, works its slow way along. A reaction was inevitable and it was swift to follow.