In the beginning, musicians typically play off of and mimic the musical forms and sounds that they are drawn to, and what resonates with them, which through repetition, forms the basis of further creative works.
Patterns hold which are constantly repeated. Notes juxtaposed together, as in chords and bass notes structured over beats, establishes an emotional base and a rhythm which excites or calms, or which can establish a number of other moods. From here, improvisation is structured, without which it just tends to whirl off into space.
