(con't from Part I)
There's something esthetically pleasing about hearing thematic material beginning again in another voice before it has a chance to fully play out; the appeal of a leader with an identical follower trailing very close behind seems to be universal (photo).
Then, by switching which voice takes the lead and which voice follows, we can come up with a second canon that sounds entirely different; the first 2 variations from this author's Op. 4 Variations on a cantus firmus in C Major are an example of this [See menu bar, Free Stuff].
Whenever a 2-part canon at the octave can be found 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 of this may be found in the scores of other compositions described on this web site [See menu bar, Free Stuff].
This author's Pastorale Op. 12 in Ab Major and the Choral from his Op. 18 Choral and Fugue in D Major are examples where the music is composed largely of canonic writing.
An entire composition might even be built around this device -- this is exemplified in this author's Canon Op. 16 in Bb Major.
The organ scholar will find it very helpful to examine these scores.