The binary form, such as we find it in the suites of Froberger and even in those of J. S. Bach, is essentially a harmonic structure. The balance and contrast which is the effect of any serviceable shape of music is here one of harmony, principally of tonic and dominant and dominant and tonic, with only a few measures of modulation for variety. There is, in addition, some contrast between that musical material which is presented first in the tonic key and that which appears later in the dominant. But, while we may speak of these materials as first and second themes or subjects, their individuality is hardly distinct and is, in effect, obliterated by the regularity and smoothness of style in which these short pieces are conventionally written. The composer makes no attempt to set them off clearly, one against the other. The entrance into the dominant key is almost never devised in such a way as to prepare the listener for a new musical thought, quite separate and different from that which he has already heard. The transitional passage from tonic to dominant emerges from the one and merges into the other, without break or distinctions. In the matter of setting his themes in their frame, Scarlatti hardly differs from his contemporaries. His style, though free and varied, is in constant motion. But his genius was especially fertile in clean-cut figures; and when, as he often does, he combines two or three distinct types of these in one short piece, the music is full of thematic variety and sparkles with an animation which at times is almost dramatic. Scarlatti is, indeed, hovering close to the sonata form in a great many of his pieces, and in one actually strikes it.[14] We shall, however, postpone a more detailed discussion of Scarlatti’s pieces in relation to the sonata form to the next chapter. The distribution of his musical material is quite whimsical and irregular, always more instinctive than experimental. It is chiefly by the quality of this material that he stands apart from his contemporaries, and as the founder of the free and brilliant pianoforte style.