Folk-song was the beginning of what we call “melody,” and the best specimens of folk-songs are quite as perfect within their small range as are the greatest works of the masters. Their contour and rhythm are sometimes as delicately balanced as the mechanism of a fine instrument. And when we remember that these melodies were the spontaneous utterance of simple, untutored peoples who, in forming them, depended almost entirely on instinct, we realize how intimate a medium music is for the expression of feeling. People who could neither read nor write and who had little knowledge or experience of artistic objects could, nevertheless, create perfect works of beauty in the medium of sound. Harmony is an adjunct to the other two elements. It is in music something of what color is in painting. As contrasted with the long line of melody and the regular impulses in time of rhythm, harmony deals in masses. Melody carries the mind from one point to another; harmony strikes simultaneously and produces an immediate sensation. Its effect upon us is probably due to a subtle physical correspondence within ourselves to combinations of sounds that spring direct from nature. The whole history of music shows a gradual assimilation by human beings of new combinations of sounds, and it is probable that only the first chapters of that history have been written. We have spoken of the synthetic quality of melody, and it is obvious that the larger the scope of music the more important this quality becomes. When a composer creates a sonata or symphony he must so dispose all his material--rhythms, melodies, and harmonies--as to give to the work perfect coherence. A work of art expressed in the element of time needs this synthesis more than one expressed in space. For although there is in music no “subject,” yet beauty is being unfolded and the need of a cumulative and coördinated expression of it is quite as great as it would be were the music “about” something. There are various ways of arranging musical material so as to attain this end. The chief principle of its synthesis is derived from the volatile nature of sound itself. It is this: that no one series of sounds formed into a melody can long survive the substitution of other series, unless there be given some restatement, or at least some reminder, of the first. The result of this is that in the early music there was an alternation of one phrase or one tune with another; and this in turn was followed by all sorts of experiments tending to bring about variety in unity. (These simple forms somewhat resemble what is known in poetry as the triolet.) The most common form in music is threefold. It is found in folk-songs, marches, minuets, nocturnes, and so forth, and--expanded to huge proportions--in symphonic movements. In folk-songs this form consists in repeating a first phrase after a second contrasting one. In minuets, nocturnes, romances, and the like, each part is a complete melody in itself.