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Anatomy of a Canon



Origin and Definition of the word "Canon"

"Canon" comes from the Greek word for rule or law. Musically, it designates the strictest form of counterpoint in which one voice is bound to imitate the rhythm, and interval content of another voice.

Requirements of a Canon

To qualify as a canon three conditions must be met:
  1. The 2nd voice must be an exact repetition or a contrapuntal derivation of the 1st.
  2. The 2nd voice must enter later than the 1st (cancrizans and proportional canon excepted)
  3. The 2nd voice may not deviate from the 1st voice or its contrapuntal variations. Thus, the 2nd voice is thought to be strictly generated by the 1st. The two voices of a canon have been called dux/comes, antecedens/consequens, or proposta/ risposta; but this study uses the terms "leader" and "follower."

    If all of the above conditions are met, the canon is said to be "strict." If liberties are taken with one or more of the above conditions, the canon is said to be "free." Canons of the 18th and 20th centuries tend to be strict, while canons of the 19th century may be free.

Canons are based, in theory, upon the principle of contrapuntal inversion...two melodic lines that can be performed simultaneously with either line functioning as the bass.

Categories of Canonic Imitation

The second voice of a canon may imitate the first voice exactly, at a different pitch level, in contrary motion, with change of rhythmic proportions, backward, or any combination thereof.

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