When the modern artist, like the Greek, selects for representation a certain part of nature, he does so because he has contrasted it, and wishes others to contrast it, with the whole of nature. When, again, in certain parts of his in sounds, on the mixture of hues entering into the general effect; and pitch in colors depending on the subdivision of light and its vibratory effects. Undoubtedly, too, it is owing partly to a subtle recognition of the correspondences just indicated that to certain effects in the arts both of sound and of sight the more general terms, tone and color, have come to be applied interchangeably. In connection with the various divisions and subdivisions under which will be treated the different phases of form to be considered it is sufficient to say that duration, limited by pauses in connection with force, as applied to the accents of syllables or notes, gives rise to rhythm; that extension, limited by outlines in connection with light and shade, as applied to contour or shape, gives rise to proportion; that quality and pitch of tone taken together furnish the possibility of developing the laws of the harmony of sound; and that quality and pitch of color furnish the same possibility with reference to the laws of the harmony of color. It is important to notice, too, that force or accent, while having to do mainly with rhythm, has a certain influence also upon tonein poetry upon the tunes of verse, and in music upon the melodic suggestions of different degrees of animation; also that, in the same way, light and shade, while having to do mainly with outline and proportion, have a certain influence also upon color. They change it in order to interpret the meaning which a colored surface is intended to convey, as, for instance, whether it is to represent what is flat or round. They suggest, too, the vitality characterizing nature. Correspondingly, also, it is important to notice that quality and pitch of sound are often necessary for the full effects of force as applied to rhythm; and that the same elements of color are often necessary for the full effects of light and shade as applied to proportion. In fact, when used in the same art, the different special effects that enter into the general effects of proportion and harmony which are now to be considered are none of them produced exclusively according to one method or to one combination of methods, but more or less according to all of them when operating conjointly.–Proportion and Harmony of Line and Color, I.