MUS 311 Counterpoint

J. The Two-Part Invention; Motive Development
Chapter 10

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Invention:

Invention--short contrapuntal work centering around the development of material from one or two motives.

Motive--melodic statement, or subject, varying in length from half a measure to two measures, usually.

Motives quickly define the key and rhythmic structure.

Good motives have some distinctive melodic or rhythmic feature that gives them interest and makes them recognizable throughout a composition.

Imitation and Countermotive:

After the motive has been stated in one voice, it is then imitated in the second voice--usually at the octave, sometimes at the fifth.

The imitation may begin immediately after the last note of the motive in the first voice, or it may overlap slightly.

Against the imitation of the motive in the second voice, the first voice may contain free material--material that does not recur as a recognizable unit, and has little linear distinction.

Or, a countermotive may be used.

Countermotive--a line that appears somewhat consistently as counterpoint to the motive. It has melodic interest of its own, yet compliments the motive, rhythmically.

Development Through Special Devices:

The motive, or other material, may be developed using the following devices:

change of interval
sequential repetition of a portion of the motive
stretto (tight overlap)
augmentation
diminution
contrary motion (inversion)
retrograde motion.

Episode

Episode--a section based on a portion of the motive or countermotive, or on new material--often two to four bars long; usually sequential.

The episode functions in modulating from the key of the statement to the next key, and provides relief from full statements of the motive.

Middle Entries

Middle Entry--a statement of the motive that occurs after an intervening episode, but before the closing section in tonic.

A cadence in a key other than the tonic generally precedes middle entries.

The most common keys for middle entries are:

In major or minor: dominant or relative major/minor, subdominant or relative major/minor, mediant, submediant.
In major: supertonic.
In minor: subtonic.

Often, there are two or three middle entries, each separated by an episode.

Final Statement

There are usually at least one or two statements of the motive in the tonic key as the final portion of the invention.

There is no "one plan" for two-part inventions, yet they have certain features in common:

Initial statement of motive (2-4) in tonic, dominant.
Episode, modulating to V (or vi) if key is major, III if minor.
One or two middle entries in key just reached.
Further middle entries in closely related keys, followed and/or preceded by episodes. Possible stretto, dominant pedal point.
Final statements of motive in tonic (1 or 2).