As far as _form_ is concerned, the work already begun is continued by Haydn. The Sonata-form tends to limit itself more and more to the first movement; more and more clearly does the “second theme” crystallise itself; slow-drawn movements are preferred more and more in the second place, and graceful rondo-like movements in the third--without, however, any appearance of compulsion. The only relic of the traditional “suite” of dances, which Haydn retains in his sonatas or symphonies, is the “Minuet” which he is so fond of using as an intermezzo.[107] The old dance-forms, _as_ dances, were so speedily forgotten, that in a certain trio a delicate slow waltz is marked as “allemande”--whereas the old allemande is not even written in the time of a waltz, apart from the difference in style.[108] [Illustration: W. A. Mozart. Engraved in 1793 by C. Kohl (1754-1807).] Haydn received more from the clavier than he gave to it. He transferred to the orchestra the clavier-forms of the time, and thus pointed out to it the path to the symphony. Without doubt the modern symphony, in the first instance, is to be traced to the clavier pieces of Philip Emanuel Bach; and Haydn, to whom fell the task of the intermediary, was the first to put the rich development of this chamber-music to practical use. Clavier and orchestra always advance in mutual rivalry, treading on each other’s heels. In Haydn it was the clavier that aided the orchestra; in Beethoven the orchestra aided the clavier; Mozart, standing between, gives to each its own. Thus it is that Mozart has given much, and much of its special character, to the clavier. This equilibrium--and Mozart is always the very personification of equilibrium--is most striking in his piano-concertos, which justly enjoy the renown of having created an epoch in this class. Especially remarkable is the C minor concerto, in which the piano experienced one of its chief emancipations. On one side stood the orchestra, on the other the instrument, and yet neither of these two great rivals loses anything of its essential nature; rather, they owe to this very rivalry many of their best effects. When clavier and orchestra address and answer each other; when the clavier intertwines itself with the strings and the wood, and they in turn blend with the clavier; when in the running strife each sounds in its own style and gives birth to a natural variation of phrases and to delicate alterations of the constituent forms; all proceeds in accordance with that self-evident logic which, at such critical points in artistic history, naturally dispenses with internal laws.