Canon

Why not start this blog with something really interesting that is Canon.
So here goes a copy of the definition taken from Douglas R. Hofstadter in his delightful book named "Gödel, Escher, Bach: An Eternal Golden Braid".

"The idea of a canon is that one single theme is played against itself. This is done by having "copies" of the theme played by the various participating voices. But there are many ways todo this. The most straight forward of all canons is the round, such as "Three Blind Mice", "Row, Row, Row Your Boar", or "Frére Jacques", Here, the theme enters in the first voice and, after a fixed lime-delay, a "copy" of it enters, in precisely the same key. Alter the same fixed time-delay in the second voice, the third voice enters carrying the theme, and so on. Most themes will not harmonize with themselves in this way. In order for a theme to work as a canon theme, each of its notes must he able to serve in a dual (or triple, or quadruple) role: it must firstly he part of a melody, and secondly it must be part of a harmonization of the same melody. When there are three canonical voices, for instance, each note of the theme must act in two distinct harmonic ways, as well as melodically. Thus, each note in a canon has more than one musical meaning; the listener's ear and brain automatically figure out the appropriate meaning, by referring to context."

--Douglas R. Hofstadter, Gödel, Escher, Bach: An Eternal Golden Braid. Copyright © 1979 by Basic Books, Inc.