[Illustration: Example 49 continued.]
These sixteen measures are the product out of eight measures, by extension; that is, they are reducible to a simple period-form (as may be verified by omitting the passages indicated under dotted lines), and they represent in reality nothing more than its manipulation and development. The original 8-measure period makes a complete musical sentence, and was so devised in the mind of the composer, without the extensions. The method of manipulation is ingenious; observe the variety obtained by the striking dynamic changes from ff to pp; and, hand in hand with these, the changes from major to minor, and back (as shown by the inflection of b-flat to b-double-flat). These are first applied to members only, of the Antecedent, as indicated by the brackets a and b, and then to the entire Consequent phrase. Observe, also, that in the repeated form of the latter, the rhythm is modified to a smoother form, during two measures. The result here achieved is constant Unity and constant Variety from almost every point of view, admirably counterbalanced.
THE PHRASE-GROUP.—A second method consists in enlarging the period-form to three phrases, by the same process of addition which, as explained in the preceding chapter, transforms the single phrase into the double-phrase or period. In order to preserve the continuity of the three phrases, it is evident that the second phrase must also close with a semicadence,—the perfect cadence being deferred until the last phrase is concluded.
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This form, be it well understood, does not include any of the triple-phrase designs which may result from merely repeating one or the other of the two phrases that make a period, as is shown in Ex. 48. All such phrase-clusters as are reducible to two phrases, because nothing more than simple repetition has been employed in their multiplication, should always be classed among ordinary periods; for two successive phrases, if connected (that is, unless they are purposely broken asunder by a definite perfect cadence at the end of the first phrase) always represent the analogy of Question and Answer.
The enlarged form we are at present considering consists of three different phrases, as a general rule; probably very closely related, or even distinctly resembling one another; but too independent, nevertheless, to constitute actual repetition, and therefore to admit of reduction to two phrases. For this very reason it cannot justly be called "period" at all, but takes the name of "phrase-group." An illustration by diagram will make the distinction clear:—
