The coming designs will prove to be expansions of the Three-Part form.
THE RONDO-FORMS .-- The structural basis of the Rondo, and other larger or (as they are sometimes called) higher forms, is the Subject or Theme.

The form and contents of this factor, the Theme, are so variable that a precise definition can scarcely be given.

It is a musical sentence of very distinct character, as concerns its melodic, harmonic and, particularly, its rhythmic consistency; and of sufficient length to establish this individuality,--seldom, if ever, less than an entire period or double-period; often a Two-Part, not infrequently a complete Three-Part Song-form, though never more than the latter.
In the Rondo-forms, two or three such Themes are associated in such _alternating succession that, after each new Theme, the first or Principal Theme recurs_.

The term "Rondo" may be referred to this trait, the periodic return of the Principal theme, which, in thus "coming round" again, after each digression into another theme, imparts a characteristic circular movement (so to speak), to the design.

In the rondos, then, all the movements of musical development revolve about one significant sentence or theme, the style of which therefore determines the prevailing character of the whole composition.