Theme (music): Meaning (information, definition, explanation, facts)

In music, a theme is the initial or primary melody. After the principal theme is announced, a second melody, sometimes called a countertheme or secondary theme, may play. In a three-part fugue, the principal theme is announced three times in three different voices -- soprano, alto, bass -- or some variation of that. In a four-part fugue, the principal motif is announced four times. A motif is a short melodic figure used repeatedly which may be used to construct a theme. A leitmotif is a motif or theme associated with a person, place, or idea.

Thematic changes and processes are often structurally important, and theorists such as Rudolph Reti have created analysis from a purely thematic perspective. Fred Lerdahl describes thematic relations "associational" and thus outside his cognitive based generative theory's scope of analysis.