CHAP. III. Simple periods. Sections. Phrases. HISTORY OF PIANOFORTE MUSIC. chief requirements of this plan, like those of any work of art, are three, viz.: Unity, Variety and Symmetry. The simplest form of composition which can give any satisfaction, regarded as a completed whole, is a single Period, the nearest analogue of which is a single couplet. A good example of this is in the church tune, " Onward, Christian Soldier," in " Hymns, Ancient and Modern." Here the period is divided into two sections, to fit the two lines of the couplet, and these two sections are balanced against each other, symmetrically. More commonly the two sections of a simple period are each divided by a c&sura, or point of partial repose. Indeed, such a division is plainly to be seen in the tune above cited. Each of the two di- visions of each section is then called a phrase. More frequently than otherwise, the third phrase is nearly or quite an exact repetition of the first, and the fourth similarly reminds one of the second, that is, they rhyme with each other, so that such a simple period is closely analogous to the ballad stanza. It is, in fact, the form commonly and necessarily used in setting such stanzas to music. The point of re- pose at the end of the first section (second phrase) is more marked than those which finish the first and third phrases, but is still only a half stop, or musical semicolon. The last section of course closes the period by a.full stop. A good example of this form is the first period of the theme in the A major son- ata of Mozart (No. 12, Peters' edition).
Another thing MONOPHONIC MUSIC. 33 must now be noticed about this period, viz. : that what gives unity to it is the repeated employment of a single melodic fragment as a pattern or design. The melodic idea, or "motive," of the first measure is repeated in the second, but in different pitch. The third measure is less obviously an imitation of the first, but still has nothing incongruous with it. The second and fourth phrases have motives differing slightly from that of the first and third, but still analogous to it, and possibly derived from it, or at least suggested by it. This use of one, or a few simple motives, of which the case cited is a very simple example, is carried out on the most elaborate scale in all large compositions. In the hands of a master, this multifarious transformation of the original motive invented, prevents unity from becoming uniformity, continually presents them in new and interesting lights, and develops from them, as from germs, a complex and elaborate whole, sat- factory to the intellect and to the artistic sense. When the composer comes to add a second period to his first, this new period will most naturally be a simple one, like the first, made up of two symmetrical sections, balanced against each other as antece- dent and consequent. This period, however, must not be wholly new, else we should have not one compo- sition, made up of two periods, but two compositions of one complete period each, wholly unrelated. The new period must, of course, contain new materials, or at least a fresh treatment of the old ones, otherwise it would be merely a repetition of the first period, c CHAP. III. Motives. Reiatfons ofperiods combined into period' groups.