Before proceeding to outline the development of the triplex form in which at least one movement of this sonata group was written and which is one of the most distinctive features of the sonata, it is not out of place to stop to consider what relationship, if any, existed between the movements. Was the sonata as a whole an indissoluble unit? Rather decidedly no. The grouping of several movements together came to be as conventional and as arbitrary, if not so regular, as the grouping of the suites. There is about the sonatas of Emanuel Bach a certain seriousness and an emotional genuineness which might prevail upon the pianist today, if ever he should think of playing them in concert, to respect the grouping in which the composer chose to present them to the world. But there is no organic life in the sonatas as a whole. Occasionally in his sonatas and in those of Clementi and Haydn the slow middle movement leads without pause into the rapid finale. In these cases, however, the slow movement is introductory to the last, to which it is attached though not related. Haydn, Mozart and even Beethoven took movements from one work and incorporated them in another. Moreover, it was the custom even as late as the time that Chopin played in Vienna, to play the first movement of a symphony, a concerto or a sonata early in a program and the last movements considerably later, after other works in other styles had been performed. The sonatas and symphonies of the last quarter of the eighteenth and the first quarter of the nineteenth centuries in the main lacked any logical principle of unity. We say in the main, because Emanuel Bach, F. W. Rust, and Beethoven succeeded, in some of their greatest sonatas, in welding the movements inseparably together. Clementi, too, in the course of his long life acquired such a mastery of the form. But these developments are special, and signalize in a way the passing on of the sonata. As a form the sonata proper was doomed by the lack of a unity which composers in the nineteenth century felt to be necessary in any long work of music. The day will come, if indeed it has not already come, when most sonatas will have been broken up by Time into the various distinct parts of which they were pieced together. Out of the fragments future years will choose what they will to preserve. Already the Bach suites have been so broken. It makes no difference that their separate numbers are for the most part of imperishable stuff. Movements of Haydn and Mozart will endure after their sonatas as wholes are dead. So, too, with many of the Beethoven sonatas. The links which hold their movements together are often but convention; and there is evidently no convention which Time will not corrode. II