>Although they may have aroused the admiration of contemporaries, the musical experiments of the 9th and 10th centuries were hardly advanced works of art. Quite simply the organum,as it was called, consisted of the liturgic chant accompanied step by step by a second voice at an interval of a fourth below it. Even here however there was scope for development since the two voices started in unison, which necessitated timid attempts at oblique and contrary movement. In practical terms this meant that, although throughout the rest of the piece the two voices moved together note for note and the contour of each melodic line was identical, at the beginning the two singers were on the same note and had to move away from each other for a brief moment in order to establish the interval between them. The reality was indeed humble. All we have from this period is a short invocation, Rex coeli, Dominewhich is described in a theoretical treatise, the Musica Enchiriadis,written by a certain Otger though long attributed to Hucbald de Saint-Amand, a composer of sequences and probably also organa.But although it stands alone, this unique example is testimony to the birth of a practice which bore within it the seeds of the whole of medieval musical art. The plainsong of the liturgy was the absolute master in this note by note 'diaphony' and the second voice, the vox organalis,was in a state of absolute submission; nevertheless the fundamental procedure of polyphony had been created.
The next great step came in the 11th century. It will be seen that of the two parts in the primitive organumso far described, it was the humble vox organaliswhich nevertheless offered the greatest scope for development. It was after all to some extent an invented part, whereas the principal voice, with the plain chant of the liturgy, could not be melodically changed precisely because it was already an established, finished melody. In the 11th century, however, not only did the movement of the vox organalisbecome freer but, more important still, it went over to the superiusor upper part, the cantus,or plainsong, being relegated to the lower voice. Furthermore the vox organalisalmost constantly evolved by contrary motion; as the line of the cantusdescended, that of the upper voice ascended and vice versa. This new style has been termed discant. But, although the parts now moved more independently, there was still a strict note to note relationship between them. The next two important changes were the liberation of the vox organalisfrom the strict demand that each note of the melody should correspond to a syllable of the text, and the developing practice of embellishing the notes of the cantuswith a brief passage of shorter notes. The art of organumhad now advanced to a stage where it could offer a vehicle for the expression of major creative talent.
The first evidence of the activity of such musical genius is found in France at the abbey of St Martial of Limoges, which exercised a seminal influence in the 12th century. The Limousin versus seems to have served as a model for the school of Notre Dame of Paris, which was to become the focal point of musical development in Western Europe. Thanks to the foregoing developments, the composer now had three musical elements to give variety and shape to long compositions. These were: the ancient monodic chant of the choir in unison, the discant organumin which two parts moved, usually by contrary motion, in a note to note equivalence, and the most advanced style of organumin which the top part embellished the slow moving plainsong melody with passages of short notes.
From the second half of the 12th century the region of the Ile de France was the nucleus of the ecclesiastical culture of Christendom for more than a hundred years. It was here that the Gothic style in architecture first reached maturity and here, too, that the first monuments of polyphony were created.
The magnificent organacomposed by the two greatest masters of the School of Notre Dame of Paris, Léonin and his successor Pérotin, achieved a beauty and fluency which raise them far above the primitive polyphony of early organum.They were large scale compositions fully capable of expressing the deepest religious mysticism. They were composed to heighten the splendor of the ceremonies on important feast days, and were based not on the ordinary of the mass, but rather on the texts of the special prayers of the service of the day (called the Proper) and almost exclusively on graduals and Alleluias, whose plan they strictly respected. They constituted in fact a new and brilliant addition to the great Gregorian tradition.
For both the two-part organumof Léonin and the more complex three- or four-part organum of Pérotin, the basic procedure was the same. The principal voice or 'tenor', so called because it 'held' the line of the liturgic cantusin the lower part, extended its notes to support the vocalisations of the upper parts. The lengthening of the notes of the plainsong was so extreme that the ear easily loses the sense of a melody, hearing rather a series of long-drawn-out pedal notes. The solid substructure of the Gregorian chant is obscured and the attention of the listener is drawn away to the elaborated interlacings of the upper parts or voces organales.The effect is almost that of extemporization on a slow moving theme. Nor is this impression wholly misleading, for contemporary treatises indicate that in a two-part organum,the shape of the vox organaliswas sometimes left to the musicianship of the performer. Discanting to the book, as it was called, was of course governed by conventions and rules known to any competent musician. Little by little however, as the possibilities available became more and more numerous and the art consequently more demanding, the part of the vox organaliswas written out and this practice became even more necessary when Léonin's double organumgave way to the triple and quadruple organumof Pérotin and his followers.
The typical pattern of one of these later works might be as follows. In the opening passage, the notes of the tenor are so long drawn out that when the note changes, the effect, to modern ears at any rate, is almost that of a modulation. The coloring of the music is completely changed as it moves from one basic pedal note to another and, although it is not entirely inapposite to introduce the term modulation, perhaps a happier analogy is with the changing appearance of a rose window in a Gothic cathedral as the sun moves round the sky. However after the first fifty bars (to use later terminology), the character of the music changes. The tenor moves more quickly, its melodic shape becomes more noticeable, and in some passages its rhythm follows that of the upper voices. The work concludes with a passage in which the tenor part reverts to the ponderous pace of the opening section and after this there might come a coda in which the upper voices vocalize above a held note in the bass. These florid decorative vocalizations at the end of a verse of the organum,or at the end of the whole composition, seem to have provided the soil from which grew the motet, the most important and influential musical form to flourish during the 13th and 14th centuries.
- Adam de la Halle
- Adam of St Victor
- Jehannot de l'Escurel
- John of Afflighem
- Léonin [Leonius, Leo, Leoninus]
- Pérotin [Perotinus Magnus]
- Petrus de Cruce [Pierre de la Croix]
Poetry and Prose