Liturgical Sequence: Origins and Formal Structure

1. Sequences

a. Origin of the Term and Liturgical Evolution

The term sequence comes from the Latin sequor, meaning "to follow," due to its position following the Alleluia in the liturgy. A monk of St. Gall, Notker Balbulus, recounted how he invented the sequence when he began writing words beneath certain long melismas to aid in remembering the melody.

Early on, the sequence separated from the liturgical chants and began to flourish as an autonomous form of composition. Hundreds appeared throughout Europe between the X and XIII centuries. There was considerable influence between the sequences and contemporary types of secular music.

Some sequences are close to the form of the hymn; Dies Irae, for example, is one such instance.

b. Characteristics and Strophic Principle of Parallelism

When the sequence functions as an independent composition separate from Gregorian chant, its features include:

• The organization of the text into pairs of lines, with occasional odd phrases interspersed among the couples.
• The verses of each couplet were sung to the same tune, but each couple possessed a different melody and varied in length.
• The pairs of lines increased in syllable count up to a limit, after which they decreased toward the end. The melody for the longest lines was often the same, marking the climax in terms of expressiveness and musical tension.

This principle is known as formal strophic parallelism and is present in secular music genres related to the sequence.

The construction was based on parallel verses, creating a literary and musical effect that doubled the composition's length. Thus, amplitude is innate to the genre, similar to hymns, but more sophisticated than the simple verse repetition found in hymns.

Strophic couplets appeared in the ninth century and expanded in the XI, XII, and XIII centuries. The first centers of composition were St. Gall, St. Martial, and Winchester.

Other Features:

• Its style presents a more syllabic and melismatic recitative than other forms.
• The proper interpretation, given its repetitive structure, was evident in responsorial or antiphonal singing. It was possibly accompanied by instruments such as the organ and fiddle.