(con't from Part II)
There's something esthetically pleasing about hearing a theme begin again in another voice before it has a chance to play out; the appeal of a leader with an identical follower trailing very close behind seems to be universal (photo).
The final passage from Prelude Internationale Op. 5 [See menu bar, Free Stuff] is an example of this.
Then, by switching which voice takes the lead and which voice follows, you can come up with a second canon that sounds entirely different; the first 2 variations from Variations Op. 4 is an example of this [See menu bar, Free Stuff].
Whenever the player can find a 2 part canon at the octave in the theme, it can lend a certain charm, serve a transitional purpose to a related key, inject additional interest when the theme is restated, assist with continuous expansion, and even boost the energy level of a coda; several more examples may be found in the scores of other compositions posted on this site [See menu bar, Free Stuff].
It's also possible to build an entire composition around canonic imitation [See blog, Getting Started With Writing, Part XI].
An example of this is Canon in Bb Major Op. 16, the score for which is also posted on this web site [See menu bar, Free Stuff].