10. The history of music may be divided into two great periods--_Ancient_ and _Modern_--the Christian era forming a dividing line between them. Each of these periods, again, may be subdivided into two other periods, one long, the other quite short--an Apprentice Period, when types of instruments were being found out, melodic or harmonic forms mastered; in other words, the tonal sense undergoing its primary education. The other, a Master Period, when an art of music suddenly blossoms out, complete and satisfactory according to the principles recognized by the musicians of the time. In the natural course of things such an art, having once found its heart, ought to go on to perfection; but this has not generally been the case. After a period of vigorous growth and the production of master works suitable to the time, a decline has ensued, and at length musical productivity has entirely ceased. Occasionally a cessation in art progress of this kind may have been dependent upon the failure of one or other of the primary conditions of successful art mentioned above, especially the failure of material prosperity. This had something to do with the cessation of progress in ancient Egypt, very likely; but more often the stoppage of progress has been due to the exhaustion of the suggestive powers of the musical instruments in use. The composers of the music of ancient Greece had for instruments only lyres of six or eight strings, with little vibrative power. After ten centuries of use every suggestion in the compass of these instruments to furnish, had been carried out. If other and richer instruments could have been introduced, no doubt Greek music would have taken a new lease of life, _i.e._, supposing that the material prosperity had remained constant. The apprentice periods of ancient history extend back to the earliest traces of music which we have, beginning perhaps with the early Aryans in central Asia, whom Max Mueller represents as circling around the family altar at sunrise and sunset, and with clasped hands repeating in musical tones a hymn, perhaps one of the earliest of those in the Vedas, or a still older one. From this early association of music with religious worship we derive something of our heredity of reverence for the art, a sentiment which in all ages has associated music with religious ritual and worship, and out of which has come much of the tender regard we have for it as the expression of home and love in the higher aspects. All the leading types of instruments were discovered in the early periods of human history, but the full powers of the best have been reached only in recent times. 11. The art of music was highly esteemed in antiquity, and every great nation had a form of its own. But it was only in three or four countries that an art was developed of such beauty and depth of principle as to have interest for us. The countries where this was done were Egypt, Greece and India.