In music notation, a ligature is a graphic symbol representing two or more notes performed in a single gesture, and on a single syllable, primarily in use ca. 800–1650 AD. They are characteristic of neumatic (chant) and mensural

Mensural notation

Mensural notation is the musical notation system which was used in European music from the later part of the 13th century until about 1600."Mensural" refers to the ability of this system to notate complex rhythms with great exactness and flexibility...

 notation. The notation and meaning of ligatures has changed significantly throughout Western music history, and their precise interpretation is a continuing subject of debate among musicologists.

Plainchant

The early notation of plainchant

Plainsong

Plainsong is a body of chants used in the liturgies of the Catholic Church. Though the Eastern Orthodox churches and the Catholic Church did not split until long after the origin of plainchant, Byzantine chants are generally not classified as plainsong.Plainsong is monophonic, consisting of a...

, particularly Gregorian chant

Gregorian chant

Gregorian chant is the central tradition of Western plainchant, a form of monophonic liturgical music within Western Christianity that accompanied the celebration of Mass and other ritual services...

, used a series of shapes called neumes, which served as reminders of music that was taught by rote

Rote learning

Rote learning is a learning technique which focuses on memorization. The major practice involved in rote learning is learning by repetition by which students commit information to memory in a highly structured way. The idea is that one will be able to quickly recall the meaning of the material the...

 rather than as an exact record of which notes were to be sung. These neumes were in use from the 9th through the 11th centuries AD for most plainsong, and differed by region. Due to their malleable nature, there were no hard and fast rules for the lengths each note was supposed to last, or even how high or low the intervals between notes were to be.

De mensurabili musica

A treatise on notation named De mensurabili musica was copied around 1260. In this treatise, the anonymous author proposed that, much in the same way that poetry of the time was based on a series of modal rhythms

Rhythmic mode

In medieval music, the rhythmic modes were set patterns of long and short durations . The value of each note is not determined by the form of the written note , but rather by its position within a group of notes written as a single figure called a "ligature", and by the position of the ligature...

, music should also be set up in this way. The notation of these modes

Rhythmic mode

In medieval music, the rhythmic modes were set patterns of long and short durations . The value of each note is not determined by the form of the written note , but rather by its position within a group of notes written as a single figure called a "ligature", and by the position of the ligature...

 was accomplished primarily through using ligatures in varying lengths and with varying degrees of complexity, where the rhythms would be derived from context. For most of their notated history, this was the purpose of ligatures: to indicate the rhythmic mode.

Franco of Cologne

Around 1250, a music theorist named Franco of Cologne

Franco of Cologne

Franco of Cologne was a German music theorist and possibly composer. He was one of the most influential theorists of the late Medieval era, and was the first to propose an idea which was to transform musical notation permanently: that the duration of any note should be determined by its...

 published a treatise on music entitled Ars cantus mensurabilis. In this treatise, Franco proposed that note values should be set up objectively, so that when looking at the notated music, a musician would be able to tell what notes were being sung or played, and the duration of those notes, with some degree of certainty. Ligatures were used for this as well, as they had become more or less standardized through the practice of the rhythmic modes.

Both of these treatises had a profound impact on the styles of Léonin

Léonin

Léonin is the first known significant composer of polyphonic organum. He was probably French, probably lived and worked in Paris at the Notre Dame Cathedral and was the earliest member of the Notre Dame school of polyphony and the ars antiqua style who is known by name...

 and Pérotin

Pérotin

Pérotin , also called Perotin the Great, was a European composer, believed to be French, who lived around the end of the 12th and beginning of the 13th century. He was the most famous member of the Notre Dame school of polyphony and the ars antiqua style...

, and through them the Notre Dame school of polyphony.

Polyphonic music from c1300-c1600

See mensural notation (ligatures).

Usage

As far as the look of ligatures, they can have two basic shapes: box (square), or oblique (angled). Additionally, some ligatures have tails that either point up or down, similar to how tails on modern note heads point up or down. While primarily contextual, the system of ligatures in use from the 13th to the 16th century is fairly standardized, if not objective. All ligatures of this period have the following principles in common:

• All ligature notes are either the length of a longa
  Longa (music)
  A longa is a musical note that could be either twice or three times as long as a breve, four or six times as long as a semibreve/whole note, that appears in early music...
  
  ("L"), a breve
  Double whole note
  In music, a double whole note or breve is a note lasting twice as long as a whole note...
  
  ("B"), or a semibreve
  Whole note
  thumb|right|250px|Figure 1. A whole note and a whole rest.In music, a whole note or semibreve is a note represented by a hollow oval note head, like a half note , and no note stem . Its length is equal to four beats in 4/4 time...
  
  ("S").
• All ligatures have at least two notes.
• For ease of discussion, ligatures of different lengths have different names. A ligature with two notes is called a binaria; one with three notes, a ternaria; one with four notes, a quaternaria; and one with five notes, a quinaria. Larger ones are possible, but rare.
• If a ligature has three or more notes, all notes in the middle (the mediae) are B.
• A downward tail changes the value of the note where the tail occurs, either from L to B or, less commonly, from B to L.
• An upward tail indicates that the next two notes are to be a series of S.
• Tails at the end of a ligature would indicate an additional note be sung or played, called a plica, that was not part of the ligature. This was especially common with the rhythmic modes to accommodate in practice what could not be accomplished within the very strict theoretical basis for modal music.

Alternate interpretations

Most scholarship on ligatures is focused on period from the 13th to the 16th centuries. Prior to this period, ligatures were far less standardized; a quaternaria ligature that, under the above rules, would mean a series like SSLB would simply mean BBBB.

Transcription

In transcribing to modern notation, where no compound graphs as ligatures exist, editors usually indicate by a hook, a bracket/brace, or (less often in polyphonic music) a slur

Slur (music)

A slur is a symbol in Western musical notation indicating that the notes it embraces are to be played without separation. This implies legato articulation, and in music for bowed string instruments, it also indicates the notes should be played in one bow; and in music for wind instruments, that the...

/phrase mark those notes that were combined into a ligature. In order to avoid confusion, many scores that are transcribed purely for performance do not include any additional notation to indicate that a particular note originally belonged to a ligature, as most of the methods to show this have separate meanings in a performance capacity.