For our purposes in this class, we will call the first section of the piece, where the
motive-countermotive pair appear 2, 3, or even 4 times in close succession, the
exposition. These multiple appearances of the motive-countermotive
may all appear with the same harmonic support, starting on the same pitch-name though in
different octaves (Inventio 3, mm. 1-4, 2 appearances; Inventio 4, mm. 1-6, 3
appearances), or with changing harmonic support (Inventio 1, mm. 1-2, 4 appearances;
Inventio 7, mm. 1-2, 4 appearances). Keep in mind that this style of imitative opening
is only one of two types of invention beginnings. The other type might be called the
contrapuntal associate, where two equal voices begin simultaneously and there is no
imitation, as illustrated in Inventio 5, 6, 9, 11, 12, 14, and 15.
As a model for the imitative opening, we will focus first on Inventio 1. Notice
how the first two appearances of the motive begin on the same pitch-name (C), and imply the
same harmonic accompaniment (tonic). The next two appearances, in m. 2, again both begin
on the same pitch-name (G), and imply dominant harmony. Measure 3 continues the tonic-dominant
progression in mm. 1-2 by resolving the harmony back to tonic. Notice further that while the
motive in the upper voice at the beginning of m. 1 is imitated by the lower voice, the
upper-voice countermotive in the last half of m. 1 is not imitated by the lower voice in
m. 2. This is very important to realize. It would've been impossible for the lower voice
to continue at the beginning of m. 2 with the countermotive from the end of m. 1 since that
countermotive implies tonic harmony, and the beginning of m. 2 is already on dominant harmony.
Notice finally that the lower-voice imitation at the end of m. 2 does not close with an
ascending 5th skip (G-D), as did the motive at the head of m. 2. Instead, it closes with a
4th skip (G-C). The end of the motive is altered so that dominant harmony of m. 2 can resolve
to tonic harmony in m. 3. Compare this exposition with that of Inventio 7.
A second type of imitative exposition is illustrated by Inventio 4. There, the
imitation do not shift from tonic to dominant harmony. Rather, all appearances of
the motive begin on the same pitch-name (D), and all imply tonic harmony. The motive
itself (mm. 1-2) does, of course, imply a progression from tonic to dominant (and then
resolves back to tonic in m. 3). Inventio 8 and 13 also illustrate this type of imitative
Inventio 5 illustrates well the contrapuntal associate. Both voices begin simultaneously,
on tonic, complementing one another melodically and rhythmically, and lead eventually to a
restatement of the voice pairing but with parts reversed, starting at m. 5, but this time on
dominant harmony. Inventio 11 follows this plan as well, somewhat modified (NB mm. 3-4!). The
dominant-harmony presentation begins at m. 7. See also Inventio 9 (dominant statement
begins at m. 17) and 14 (dominant statement begins at m. 6.
In sum, there are two basic types of invention openings, the imitative and the contrapuntal
associate. The imitative type has two subtypes: tonic/dominant alternation and all tonic entries
of the motive. In the type based on the contrapuntal associate, the voice pairing is presented
first in tonic and then, possibly after a transition, in or on dominant.
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