They are not classified; the student must determine whether the form is pure First Rondo, or an intermediate grade between Rondo and "Song with Trio." One of the examples is a genuine Song with Trio; and one is a _Three-Part Song-form_; with reasonable vigilance the student will detect these "catches." To distinguish these three designs from each other, recollect-- That the Three-Part Song-form consists of three _single Parts_, fairly similar in character, fairly small in form, and severed either by a firm cadence, or by unmistakable proof of new "beginning;" That in the first Rondo-form, at least one of the themes (if not both) contains _two_ (or three) Parts; and, That in the Song with Trio, the two "Songs" are more independent of each other, and more decisively separated, than are the "themes" of the Rondo-form.
With reference to all uncertain cases, it must be remembered that _the more doubtful a distinction is, the less important is its decision_.
These designs naturally merge one in another, and at times it is folly to impose a definite analysis upon them.
The analysis should be as minute as possible, nevertheless.

The first step is to define the extremities of the two themes.

This fixes the coda (and the introduction, if present); the re-transition (returning passage into the Principal theme); and the transition into the Subordinate theme--if present.

The form of each theme must be defined in detail, as in Ex.

54:-- Beethoven, pianoforte sonatas: op.