Double canon (music)

In music, a canon is a contrapuntal (counterpoint-based) compositional technique or texture that employs a melody with one or more imitations of the melody played after a given duration (e.g., quarter rest, one measure, etc.). The initial melody is called the leader (or dux), while the imitative melody, which is played in a different voice, is called the follower (or comes). The follower must imitate the leader, either as an exact replication of its rhythms and intervals or some transformation thereof (see "Types of canon", below). Repeating canons in which all voices are musically identical are called rounds—"Row, Row, Row Your Boat" and "Frère Jacques" being widely known examples.

Why are some composers fascinated with canons? Canons are not unlike puzzles and other brainteasers: from just a few rules, you can achieve so much. Plus, canons have the appeal of any puzzle. There is the initial challenge, the mystery of solving it, and the feeling of satisfaction you get from completing it. (Davidian 2015, 136)

Accompanied canon is a canon accompanied by one or more additional independent parts which do not take part in imitating the melody.

During the Middle Ages, Renaissance, and Baroque—that is, through the early 18th century—any kind of imitative musical counterpoints were called fugues, with the strict imitation now known as canon qualified as fuga ligata, meaning "fettered fugue" (Bridge [1881], 76; Mann, Wilson, and Urquhart n.d.; Walker 2000, 1). Only in the 16th century did the word "canon" begin to be used to describe the strict, imitative texture created by such a procedure (Mann, Wilson, and Urquhart n.d.). The word is derived from the Greek "κανών", Latinised as canon, which means "law" or "norm", and may be related to 8th century Byzantine hymns, or canons, like the Great Canon by St. Andrew of Crete. In contrapuntal usage, the word refers to the "rule" explaining the number of parts, places of entry, transposition, and so on, according to which one or more additional parts may be derived from a single written melodic line. This rule was usually given verbally, but could also be supplemented by special signs in the score, sometimes themselves called canoni (Bridge [1881], 76). The earliest known non-religious canons are English rounds, a form called rondellus starting in the 14th century Mann, Wilson, and Urquhart n.d.; the best known is Sumer Is Icumen In (composed around 1250), called a rota ("wheel") in the manuscript source (Sanders 2001a; Sanders 2001b).

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