Also Chopin, Nocturne No. 13 (op. 48, No. 1).
Examples of this compound Song-form will also be found, almost without exception, in Marches, Polonaises, and similar Dance-forms; and in many pianoforte compositions of corresponding broader dimensions, which, if extended beyond the very common limits of the Three-Part form, will probably prove to be Song with Trio. This the student may verify by independent analysis of pianoforte literature,—never forgetting that uncertain examples may need (if small) to be classed among the group-forms, or (if large) may be suspected of belonging to the higher forms, not yet explained, and are therefore to be set aside for future analysis. Mention must be made of the fact that in some rare cases—as in Mendelssohn's well-known "Wedding March"—two Trios, and consequently two da capos, will be found.
CHAPTER XIII. THE FIRST RONDO-FORM.
EVOLUTION.—It cannot have escaped the observant student of the foregoing pages, that the successive enlargement of the structural designs of musical composition is achieved by a process of natural growth and progressive evolution. No single form intrudes itself in an arbitrary or haphazard manner; each design emerges naturally and inevitably out of the preceding, in response to the necessity of expansion, and conformably with the same constant laws of unity and variety,—the active agents, along the entire unbroken line of continuous evolution, being reproduction (Unity) and legitimate modification (Variety); or, in other words, modified repetition. It is upon the indisputable evidence of such normal evolution in the system of musical structure, that our conviction of the legitimacy and permanence of this system rests.
The diagrams which appear on pages 78 and 98 partly illustrate the line of evolution, which, in its fullest significance, may be traced as follows: the tone, by the simplest process of reproduction, became a figure; the figure, by multiplication or repetition, gave rise to the motive; the latter, in the same manner, to the phrase. The repetition of the phrase, upon the infusion of a certain quality and degree of modification (chiefly affecting the cadences) became the period; the latter, by the same process, became the double-period. The limit of coherent phrase-succession (without a determined interruption) being therewith reached, the larger Part-forms became necessary. The Two-Part form emerged out of the double-period, the two "connected" periods of which separated into two "independent" Parts, by the determined interruption in the center. And, be it well understood, each new design having once been thus established, its enlargement within its own peculiar boundaries followed as a matter of course; I mean, simply, that the two Parts did not need to remain the periods that were their original type; the process of growth cannot be stopped. The Three-Part form resulted from adding to the Two-Part the perfecting reversion to the starting-point, and confirmation of the principal statement. The Five-part form, and the Song with Trio are enlargements of the Three-Part forms by repetition or multiplication; and with the latter the limit of this particular process appears to be achieved. Any further growth must take place from within, rather than by addition from without.
But the process of evolution continues steadily, as the student will witness. To one vital fact his attention is here called,—a fact which he is enjoined to hold in readiness for constant application,—namely, that perfection of structural design is attained in the Three-Part form, and that every larger (or higher) form will have its type in this design, and its basis upon it. 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. This, which is naturally called the Principal theme, is placed at the beginning of the rondo. Its end being reached, it is temporarily abandoned for a second sentence, called the Subordinate theme, of more or less emphatically contrasting style and of nearly or quite equal length (generally shorter, however), and always in a different key. After this there occurs the momentous return to the beginning,—the most insistent and vital fundamental condition of good, clear, musical form, of whatsoever dimension or purport,—and the Principal theme reasserts itself, recurring with a certain degree of variation and elaboration (occasionally abbreviation), thus vindicating its title as Principal theme, and stamping its fellow-theme as a mere digression. After this,—if a still broader design is desired,—another digression may be made into a new Subordinate theme, in still another key, followed by the persistent return to the Principal theme. And so on. Upon the Subordinate theme, or themes, devolves the burden of variety and contrast, while the Principal theme fulfils the requirements of corroboration and concentration. A coda, sometimes of considerable length, is usually added; it appears to be necessary, as a means of supplying an instinctive demand for balance, increased interest, and certain other scarcely definable conditions of very real importance in satisfactory music form.
Of the Rondo-forms there are three grades, distinguished respectively by the number of digressions from the Principal theme:—