It is not the intention of the author of the following sketch to comprise in it strictures on every department of the musical art, a labour which would lead far beyond the limits assigned to this preliminary discourse, but simply to give an abstract of the modern European system of music, considered in its essential and constituent parts, which comprehend the laws of sounds or of notes; rhythm; séméiotechnie, or the system of musical characters; and, lastly, composition, which is so closely allied to the former subjects, that it would be difficult to divide them without a diminution of perspicuity and interest. I shall treat then, in the most summary manner, of all these compartments together; and this union will be the more easy, as the progress of these different subjects is simultaneous, and is often comprised in the writings of the same author. Although no great improvement is effected in any art suddenly, and without much previous thought and consideration, and though every such discovery is introduced in so gradual a manner, as to be hardly perceptible, yet there are periods when accumulated observations, and wants generally felt, lead men who are happily organized, or placed in favourable circumstances, to seize on more extensive views of a subject, and to create more powerful methods of arriving at a knowledge of it, the superiority of which soon becomes generally experienced, and eventually leads the habits and ideas of the whole mass of mankind in a new direction. These rare moments, which are, however, renewed at intervals, form what is called periods. They are more or less remarkable, according as the object attained is more or less important.