The other noticeable feature of Haydn's treatment of the variation-form is illustrated very happily by the 'Andante con Variazioni' in F minor for clavier solo, and by the movement in the F major sonata for clavier and violin; both showing how strongly he regarded the form as one to be unified in some way or other beyond the mere connection based on identity of structure or tune which is common to all the members of the series. The first of these is really a set of variations on two themes; since the principal theme in the minor is followed by a slighter one contrasting with it, in the major. The variations on these two themes alternate throughout, and end with a repetition of the principal theme in its original form, passing into an elaborate coda full of allusions to its principal figures. Thus there is a double alternation of modes and of styles throughout binding the members together; and the free development of the features of the theme in the coda gives all the weight and interest necessary to clench the work at the end. The slow movement for clavier and violin is somewhat different in system, but aims at the same object. After the theme comes an episode, springing out of a figure in the cadence of the theme, and modulating to the dominant and back; then comes the first variation in full, followed by another episode modulating to B♭, with plenty of development of characteristic figures of the theme, coming back (after about the same length as the first episode) to a pause on the dominant chord of the principal key, and followed by another variation with demisemiquaver ornamental passages for the pianoforte. This variation deviates a little at the end, and pauses on the dominant chord again; and then the beautiful and serene theme is given out once more in its original form. This is therefore an ingenious kind of Rondo in the form of variations. The short contrasting episodes are quite in Rondo-form, the only difference being that the two middle repetitions of the theme are made unusually interesting by appearing in a fresh guise. One more point worth noting about Haydn's works of this kind, is that some of his themes are so rich and complex. In a few of the sets in the quartets the theme is not so much a tune as a network of figures combined in a regular harmonic scheme—see Ex. 17; and the same holds true of the 'Andante con Variazioni' mentioned above, which is long, and full of the most various and remarkable figures. It may be said finally that there is no branch of composition in which Haydn was richer and more truly polyphonic than in his best sets of variations.
Mozart, on the other hand, represents the extreme of the melodic form of variations. If in many of Haydn's slighter examples this tendency was perceptible, in Mozart it comes to a head. The variations which he makes purely out of ornamental versions of the tune of the theme, are at least four times as many as his harmonic and more seriously conceived ones. As has been said before, Mozart wrote far more sets than Haydn, and many of them were probably pièces d'occasion—trifles upon which there was neither time nor need to spend much thought. It is scarcely too much to say moreover that variation-writing was not Mozart's best province. Two of his greatest gifts, the power of moulding his form with the most refined and perfect accuracy, and spontaneous melody, have here no full opportunity. The themes which necessarily decide ths form are in many cases not his own, and, except in rare instances, it does not seem to have entered into his head to try to make new and beautiful melodies on the foundation of their harmonic framework. He seems rather to have aimed at making variations which would be easily recognisable by moderately-gifted amateurs; and it must be allowed that it takes a good deal of musical intelligence to see the connection between a theme and a variation which is well enough conceived to bear frequent hearing. It is also certain that the finest variations have been produced by scarcely any but composers of a very deep and intellectual organisation, like Beethoven, Bach, and Brahms. Mozart was gifted with the most perfect and refined musical organisation ever known; but he was not naturally a man of deep feeling or intellectuality, and the result is that his variation-building is neither impressive nor genuinely interesting. Its chief merits are delicate manipulation, illustrating the last phase of harpsichord-playing as applied to the Viennese type of pianoforte with shallow keys, and he obtains the good balance in each set as a whole without any of Haydn's interesting devices. A certain similarity in the general plan of several of the independent sets suggests that he had a regular scheme for laying out the succession of variations. The earlier ones generally have the tune of the theme very prominent; then come one or two based rather more upon the harmonic framework, so as to prevent the recurrence becoming wearisome; about two-thirds of the way through, if the theme be in the major, there will be a minor variation, and vice versâ; then, in order to give weight to the conclusion and throw it into relief, the last variation but one has a codetta of some sort or an unbarred cadenza, or else there is an unbarred cadenza dividing the last variation from the final coda, which usually takes up clearly the features of the theme. These unbarred cadenzas are a characteristic feature of Mozart's sets of variations, and indicate that he regarded them as show pieces for concerts and such occasions, since they are nothing but pure finger-
