Canon

Canon, in Music (from the Gr. kanōn, 'a rule'), is the species of Imitation (q.v.) most strictly according to rule. The melody given out by one part is repeated note for note by the successive parts which follow at any interval of time and position in the scale. When produced between two parts it is called 'two in one,' when between three, 'three in one,' at the octave, fifth, or any other interval. Two or more canons may be carried on simultaneously; a piece for eight parts, consisting of four canons each between two voices heard simultaneously, is termed a canon 'eight in four.' Other parts may be heard, not in imitation, along with those in canon. The imitation may also be made by means of the devices of inversion, diminution, augmentation, retrogression, &c. The latter is termed a canon 'cancrizans,' from its crab-like motion. When a canon terminates by a few notes not in imitation, forming a cadence, it is called finite; but when it returns again to the commencement it becomes 'circular,' or 'infinite.' Canons are found in both instrumental and vocal works, and composers of all ages have shown their skill in constructing them. They abound in the works of the older writers, and occasionally considerable works were constructed wholly in canon—e.g. a Mass by Alessandro Scarlatti. Frequently they were more curious and enigmatical than beautiful; in modern music they appear in their proper aspect as incidental, or as merely an ingenious play upon notes. Byrd's well-known Non nobis Domine may be referred to as a specimen of canon. A full treatment of the subject will be found in the works upon counterpoint and fugue by Marpurg, Cherubini, or Ouseley.