Anatomy Room
Contrapunctus inversus 12 a 4

／Contrapunctus inversus a 4

Mirror fugue with 1 theme, 4 voices, 3/2 beat, 56 bars each

Mirror fugue is a piece that makes it possible for the whole piece to be
inverted. The image and the mirrored image are printed side by side on both
sides in the first edition of the art of fugue.

Taking ゛h-c'゛ as a pivot, the top and the bottom are inverted, therefore, ゛
d ゛reflects ゛a'゛ and ゛a゛ reflects ゛d'゛. Many mirror music could be made
easily if they were simply made from inversing a whole piece upside down,
however, making it possible to be performed and heard naturally, there are
some restrictions as follows. ; Disapproval for transposition to a remote
key, and frequent use of syncopation and tonic in a highest voice.
Limitation for a register between highest and lowest key.

Rhythmic change of 3/2 in the common theme is notated. The counter
theme is accompanied to the response, the following theme and the
response.



The lower column becomes the mirrored image in the music above. As a
comparison, the two images are placed in parallel here though simultaneous
performance is not realized. Now, we would like to touch on the image only.

Sequence can be found from bar 17. One part of the theme is repeated in
the upper two voices.



The slurred motive in bass in the above music gives a hint to a later coming
variant theme.



It is the variant theme that you see in soprano above and the same theme
can be seen in alto from bar 26, in tenor from bar 32 and in bass from bar
42.　Like an echo, the motive at the beginning of the theme repeats in
tenor from bar 21, alto from bar 22 and bass from bar 22. This motive often
reappears together with the theme likewise.



Slightly different variant theme from the others is stated in alto from bar
55, in which the former motive is used repeatedly, bearing a stretto-like
effect.

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