Where a voice entered first, the mirror enters it last. Where a motive is stated by the soprano, the mirror states it in the bass. Tonic pitches are replaced by dominants and dominants by tonics. While this reversal can be heard in the subjects, it is especially audible in pedal tones. Click the following examples to hear the difference.
Modulations move in the opposite direction.
Where a sequence went up, in the mirror it goes down. Whereas Johann Sebastian did not specify instrumentation for his Art of Fugue, Carl Philipp Emanuel included transcriptions of Contrapunctus XIII for duo harpsichords. While we do not know who transcribed them, these arrangements represent the practice of the Bach household where improvisation was clearly the order of the day. This canon is one of the best examples in music literature of not only proportional canon , but also canon in contrary motion , and double counterpoint at the octave . Please refer to the Canons of the Art of Fugue study for an analysis of this canon .