A motive is the smallest identifiable
musical idea. Motives may be developed into
phrases,
periods, full
melodic ideas, and even entire large scale pieces.
For instance, the motive of
Beethoven's fifth symphony is introduced first thing. The opening four
notes (three
eighth notes followed by a
quarter note under
fermata) outline everything that happens for the rest of ths
symphony. The entire
harmonic and melodic
structure can be traced back to the
minor third interval in the opening
statement.
To begin a new piece, a
composer will often times decide on a motivic subject and then
develop it through
exposition and
improvisation (sometimes on paper, other times at the
keyboard) until a solid,
coherent thread of development is acheived.