Notre Dame School

The Notre Dame School is the designation for a school of French polyphonic music around 1200, whose leading composers -- the only ones known by name -- were Leonin (second half of the 12th century) and Perotin (c. 1160-1220).  The name is based on the surmise (a very likely one) that both masters were connected with the famous cathedral of Paris.  The repertory of the school of Notre Dame consists of a collection of two-part organa known as the "Magnus liber organi" (Great Book of Organum) (59 pieces for the Mass and 34 pieces for the Offices), additional organa in two, three, and four parts, and numerous clausulae, conductus, and early motets.

School of St. Martial

An important school of the 10th to 12th centuries located at the Abbey of St. Martial in Limoges (also known as the school of Limoges).  Aside from composing many sequences and tropes (chiefly 10th and 11th centuries), it is important mainly for its contribution to the development of organum, in which the polyphonic school of St. Martial (c. 1100-1150) immediately preceded Notre Dame.

Leonin

Leonin, the first great Notre Dame composer and choirmaster around 1160, laid the foundation for the system of rhythmic modes and was considered the best composer of organa.  He is attributed with the writing of the "Magnus Liber...", which was based on the Gradual and Antiphonal.

With Leonin's work, the process of elimination of the melodic function of the tenor was complete.  With its arrangement of voices and the rhythmically organized character of the duplum, Leonin's organum obscured the original purpose of the chant to such a point that it is now important only as a starting point for the addition of the second voice.  Many of his melodic patterns were triadic, something not heard in chant melodies previously.

Leonin employed two techniques.

• In one, the plainsong melody is in enormously long notes and the organal part free and unmeasured in rhythm, with very complex melismata.  This free melismatic style tends to be employed when the original plainsong melody is syllabic.
• In the other, which was called discantus style, the two parts move note for note, in rhythmic modes or patterns derived from troubadour music.  The discantus technique is used when the plainchant is lyrically elaborate.

Leonin's organa set the soloistic portions of responsorial chants of the Mass and Offices to polyphony, while the choral material remained in plainchant.  He juxtaposed old and new elements, with passages of florid organum alternating with livelier discant clausulae.

Perotin

Succeeded Leonin at Notre Dame.  He developed organum from the Leonin style by instilling a greater rhythmic accuracy, and by making additions and modifications to the "Magnus Liber Organi".  His tenor voices were written in a series of rhythmic motives that were the precursors of the the rhythmic modes.  He expanded organum to three and four voices.  Three-voice organum became the standard with Perotin.  In addition, his music shows evidence of canonic imitation.

Perotin was skilled in the art of discant, being described as "optimus discantor," while Leonin was called "optimus organista."

Conductus

The monophonic conductus was probably first sung while a participant in the Mass or liturgical drama was "conducted" or moved from one place to another in the altar area of the church.  The text was metric, and not liturgical.  The melody was not taken from a chant collection, and was freely composed.  This form was first associated with the church but soon became a secular form, and the title was applied to almost any Latin song of a serious nature.

Organum

As early as the 9th century a practice of singing in parallel fourths and fifths began and was called organum. Several types developed that were variously named. They all had the common characteristic of using a preexisting chant (vox principalis), to which was added one or more melodic lines.

• Parallel organum added a second voice (vox organalis), fixed at the interval of a fifth or fourth below the vox principalis.
• Free organum employed contrary and oblique motion in the vox organalis, whereas a later type,
• melismatic organum, used elaborate decorative note groups in the vox organalis against the very slow-moving values of the vox principalis.

All styles of organum emphasized the use of the perfect intervals of the unison, fourth, fifth, and octave at cadential points.

Clausula

The term is employed mainly for a large repertory of polyphonic compositions of the late 12th and early 13th centuries (school of Notre Dame) that are based on a short fragment of a Gregorian chant, in contrast to the organa, which are based on the entire chant.  They are relatively short compositions, invariably based on a melisma of a responsorial chant.  Accordingly, there is no full text in the tenor of a clausula, but only one or two words (incipit) or sometimes only a syllable to indicate from which chant the tenor is borrowed.  Many such clausulae (well over 500; about a dozen in 3 parts, the others in 2) are preserved in the sources of Notre Dame.  They were probably intended to serve as substitutes for the corresponding sections in the organa of Leonin.

Most of the early motets are directly derived from clausulae, retaining their music but underlaying a full text to the upper part.

Discantus

A 12th- to 15th-century term for certain types of polyphonic music in which a part was composed against the plainsong, or in some cases perhaps improvised.  In distinguishing discant from organum, the former designates two-voice polyphony in note-against-note style, the latter a more elaborate setting employing (or at least including) melismas in the upper part.

The term "discant" originated as a designation for the upper voice only, the lower part being called "cantus" ("cantus" = voice; "discantus" = second, or counter, voice).  It came to denote the style used in the so-called discant sections of the organa of Notre Dame and in the two types of polyphony that originated from these, the clausula and motet.  Stylistically, the conductus also belongs to the category of discant.  Its opposite is the "organal" sections, in which the upper part moves in long melismas above a few sustained notes of the tenor.