A Dictionary of Music and Musicians/Imitation
IMITATION is a name given to one of the most useful and indeed necessary devices in contrapuntal composition. It consists in a repetition, more or less exact, by one voice of a phrase or passage previously enunciated by another, e.g.—
In the former of these examples the imitation takes place at one bar's distance, and at the interval of an eleventh above. In the latter it is at the interval of an octave below.
If the imitation is absolutely exact as to intervals it becomes a Canon. But in the majority of cases imitations are not canonical. Imitations may take place at any interval or at any distance. They may also be sustained by any number of voices or instruments, e. g.—
where we have an imitation in four parts.
Imitations are sometimes conducted by contrary motion of the parts, or 'by inversion,' e.g.—
More rarely we meet with imitations per rectè et retrò or, as they are sometimes called, 'by reversion,' in which the antecedent, being read backwards, becomes the consequent:—
(These examples are all taken from Fétis.)
Imitations may also be made by inversion and reversion, or by 'augmentation,' or 'diminution.' It will be needless to give examples of all these different kinds. Good examples may be found in the theoretical works of Baltiferri, Azopardi, Zimmermann, Marpurg, Fux, and Cherubini. The Suites and Fugues of Bach, the Symphonies and Sonatas of Haydn, Mozart, and Beethoven are full of good examples of various kinds of imitation. In fact every classical writer, whether of vocal or instrumental music, has derived some of his finest effects from a judicious employment of such artifices. Every student of music must make himself familiar with these contrapuntal resources if he would fain scale the loftiest heights and make himself distinguished as a composer of high-class music.