The number of qualities in use in music--twelve in our scale of equal temperament--is, of course, not all there are in the world of tones; they are a human and arbitrary selection, governed by technical and historical motives, into which we shall not enter. Peoples with a different culture have made a different selection. But we are not concerned with the music of angels or of orientals, but with our own. With these twelve, with their possible variations in pitch, loudness, and tone-color, the musician has a rich and adequate material. All the elements of an aesthetic experience are present in striking simplicity even in the single musical tone. There is the sensuous medium, the sound; there is a life expressed, a feeling aroused in us, yet so completely objectified in the sound that it seems to belong to the latter on equal terms with color or quality or loudness; there is a unity and variety and orderly structure in the dominance of the fundamental among the overtones and the fusion of all in the total clang. Thus every note is a complete little aesthetic organism. Yet the beauty of single tones is very slight,--less, I think, than that of single colors; they need the contrast or the agreement in consonance with other tones in order to awaken much feeling; they must be members of a wider whole; observe how, when sounded after other tones, they become enriched through the contrasting or consonant memory of those tones. Nevertheless, the single tone has its feeling, however slight, and to understand this is to go a long way toward understanding the more complex structures of music.