In sculpture, poetry, and architecture we have seasons of reverting to the antique, and with good results. These arts dealt with tangible material, could be kept present to the eye and mind, and therefore developed quickly. We return to their ancient forms, so restful in their conformity to natural adjustment, for relief from the tireless ingenuity of modern producers, and to find bases for new flights. Music is, however, so essentially intangible that it required ages to discover sufficient of its underlying principles to afford the foundation for an art. Nothing within our ken has been as slow in evolving, and yet nothing has shown such an unwavering tendency forward and upward. These characteristics, and its insidious influence upon man's nature, entitle it to be called the divine art. It is in course of evolution from its original germ, but the outlines of its early technical forms have no significance for the nineteenth-century composer. For the above reasons statistics will be avoided when they are not essential in locating and verifying conditions. Some periods were too influential in broadening and defining the scope of musical expression to be ignored. I shall endeavor to make my theories in regard to the origin and growth of music accord with its inherent qualities, as well as with man's devious and changing nature. The greater the music the more direct is its appeal to our imaginations, and the stronger its effect upon our emotions. Each intrinsically great composition has its distinguishing mood or temperament, which is the sequential expression and perpetuation of an emotion. This mood is first announced by the chosen themes, and then its varied phases and the cumulative intensity essential to sustained expression are secured through the logical manipulation of these themes. I would divide music into two classes, natural and artificial. The latter class is, as the name assigned to it implies, a mechanical combination of musical means, the result of purely intellectual processes, incited by will force, and not by inspiration. It lacks all reason for being, and I shall dismiss it without further ceremony. It is to natural music, which springs from our imaginations, is formulated for purpose by intellect, appeals to the sympathies, and sways the emotions, that I shall devote my attention. The music of the barbarous races, although developed little beyond the initial stage, is adapted in its character to their habits and sensibilities, and is among them quite as powerful an agency for stimulating the passions as is our nineteenth-century music among the people of this Western civilization. Their musical exercises are purely emotional, and therefore natural. Natural music is composed of two species, that which is earnest and edifying, and that which is entertaining only. These diverse growths are equally spontaneous, and each develops form, substance, and proportions in keeping with the intellectual soil by which it is nurtured.