A short musical idea, a salient recurring figure, musical fragment or succession of notes. Without this small structural unit of music, a symphony would not be possible.

An expression that has a complete musical sense of its own, built from motives and other smaller musical ideas, combining to make larger musical structures.

The melodic subject matter of a piece of music. A theme is built from multiple phrases, and is the recognizable melody upon which a composition is typically based.

A self-contained part of a musical composition or musical form, that is the result of the thoughtful presentation and development of musical themes. Individual movements of a symphony can be performed separately, and provide a satisfying experience to the listener.

An extended musical composition comprised of several movements, typically four. The symphony is the entirety of the musical journey, bringing each of the musical motives, phrases, themes, and movements into a unified whole.