Upon the whole, all the improvements of the time arrange themselves into two categories, namely: The better proportion, contrast, and more agreeable succession of moments in art works; and, second, the more ample means for intense expression. In the department of form, indeed, there was a very important transition made between the first half of the century and the last. The typical form of the first part of this division was the fugue, which came to a perfection under the hands of Bach and Haendel, far beyond anything to be found in the form previously. The fugue was the creation of this epoch, and while based upon the general idea of canonic imitation, after the Netherlandish ideal, it differed from their productions in several highly significant respects. While all of a fugue is contained within the original subject, and the counter-subject, which accompanies it at every repetition, it has an element of tonality in it which places it upon an immensely higher plane of musical art than any form known, or possible, before the obsolescence of the ecclesiastical modes. Moreover, the fugue has opportunities for episode, which enable it to acquire variety to a degree impossible for any form developed earlier; and which, when these opportunities were fresh, afforded composers a field for the display of fancy which was practically free. This, one may still realize by comparing the different fugues in Bach's "Well Tempered Clavier" with each other, and with those of any other collection. It is impossible to detect anywhere the point where the inspiration of the composer felt itself bound by the restrictions of this form. It was for Bach and Haendel practically a free form. And the few other contemporaneous geniuses of a high order either experienced the same freedom in it, or found ways of evading its strictness by the production of various styles of fancy pieces, which, while conforming to the fugue form in their main features, were nevertheless free enough to be received by the musical public of that day with substantially the same satisfaction as a fantasia would have been received a century later. Roughly speaking, Bach and Haendel exhausted the fugue. While Bach displayed his mental activity in almost every province of music, and like some one since, of whom it has been much less truthfully said, "touched nothing which he did not adorn," he was all his life a writer of fugues. His preludes are not fugues, and their number almost equals that of the fugues; but the operative principles were not essentially different--merely the applications of thematic development were different. Yet strange as it may seem, within thirty years from his death it became impossible to write fugues, and at the same time be free. Why was this?