This discursiveness is a natural characteristic of the formative period in the evolution of sonata-form, before composers had learned the necessity of a close logical development throughout.
The "restatement after contrast" in sonata-form is commonly known as the "recapitulation." In the early specimens of the form the recapitulation was, except in its harmonies, almost identical with the exposition. Here the first theme is reduced to one half its original length, which is rather an unusual abbreviation. Mr. Hadow, in his "Sonata Form," lays down the following rule for this portion of the movement: "The recapitulation should not contain any noticeably fresh material; it should follow the main thought of the exposition with no important parentheses or divergences, and, when it varies, should do so in a manner which does not obscure the subjects, but only sets them in a new light."
In Figure XXXVIII is shown the foregoing plan in the form of a diagram. This should be compared with the similar diagrams in Chapter IX.
FIGURE XXXVIII.
TABULAR VIEW OF SONATA-FORM, OR FIRST-MOVEMENT FORM.
| A Exposition | B Development | A Recapitulation |
| Introduction (optional) Theme I, usually followed by a short transition, or link Theme II in contrasting key | This section is based on themes already presented in the Exposition | Theme I. Transition (?) Theme II in tonic or home key |
| Coda | Coda | |
| (Duality of harmony) | (Plurality of Harmony) | (Unity of Harmony) |
IV. HARMONY AS A PART OF DESIGN.
There remains to be considered the important factor of harmony, or arrangement of keys. This arrangement is shown in the diagram, Figure XXXVIII; but the principle involved is an important one, and the mere statement of Duality, Plurality and Unity hardly suffices to explain it. There seems to be no doubt that the subtle uses composers make of harmony are less intelligible to the average listener than are the uses of themes. A theme represents, as it were, a line, and since it is the tune that, for most listeners, constitutes the music the attention of the listeners is readily drawn to changes which materially affect it. Harmonic design, on the other hand—the setting of one key or series of keys against another—is often only dimly recognized, if at all, although it is of the greatest importance in all modern music. In sonata-form the harmonic plan (described above by the terms Duality, Plurality and Unity) adds an important element since it unifies the last section by stating both first and second theme in the same key. And in the middle, or development section, the freedom of harmonic progression—the multitude of keys—gives great variety and enables the composer freely to indulge his fancy.
In the present movement Bach chooses at times certain remote keys that impart to this section of the piece a charm of their own. The passage beginning on the second beat of measure 54 illustrates this: the four measures that follow are all in the remote key of F-flat major. (The reader should examine each of the modulations that occurs in the development section.) However unconscious of the charm of harmonic variety the average listener may be, he would surely be conscious of monotony were the piece all in one or even two keys. And since the tendency of the music of to-day is to exalt harmony at the expense of melody, it is desirable that the student should pay particular attention to these early phases of harmonic structure, so as to be able to appreciate this important element in modern music. In fact the whole progress of music since Haydn has been steadily onward towards a free use of the different keys, and as our ears have become accustomed to new combinations of chords, we have gradually come to feel the beauty that lies in glowing musical colors, and to accept them as a legitimate means of expression. In our chapters on Beethoven this phase of musical development will receive fuller attention.