GEB

(Like Gödel, Escher, Bach)

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 to do this
The most straightforward of all canons is the round
Such as "Three Blind Mice", "Row, Row, Row Your Boat", or "Frère Jacques"
Here, the theme enters in the first voice and after a fixed time delay a copy of it enters in precisely the same key
After 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 be able to serve in a dual or a triple or a quadruple role
It must firstly be part of a melody, and secondly it must be part of a harmonization of the same melody
When the 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 the canon has more than one musical meaning
The listener's ear and brain automatically figure out the appropriate meaning by referring to context

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
(The idea of a canon is that one single theme is played against itself)