Puzzle canon

In music, a canon is a contrapuntal (counterpoint-based) compositional technique 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" are popular examples.

An accompanied canon is a canon accompanied by one or more additional independent parts that do not imitate 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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