The first Rondo differs from the latter, however, in being more compact, more coherent and continuous, and more highly developed.

This manifests itself in the relation of the Themes to each other, which, despite external contrast, is more intimate than that between the Principal and Subordinate Song (or Trio); further, in the transitional passages from one Theme into the other (especially the Re-transition, or "returning passage"); in the customary elaboration of the recurring Principal Theme; and in the almost indispensable coda, which often assumes considerable importance, and an elaborate form and character.
The evolution of the First Rondo-form of the Song with Trio may be clearly traced in classic literature.

Many intermediate stages appear, naturally; and it is sometimes difficult to determine whether the design is Rondo or compound Song-form, simply because it is scarcely possible to decide just when the "Trio" assumes the more intimate relation of a Subordinate theme, or when the freedom and comparative looseness of association (peculiar to the Song with Trio) is transformed into the closer cohesion and greater smoothness of finish _which fuses all the component Parts of the design into one compact whole_,--the distinctive stamp of all so-called "higher" forms.
The thoughtful examination and comparison of the following four examples will elucidate the matter:-- 1.

Beethoven, first pianoforte sonata (op.

2, No.