Tones and Tone-Relations
122. Up to this point I have avoided the consideration of Tones and Tone-Relations. I have spoken of possible changes of tone in dots and in lines; changes of value, of color, of color-intensity; but it is not in dots nor in lines that these changes call for particular attention. Our interest has been in the positions, measures, shapes, and attitudes of dots and lines, and in the possibilities of arrangement and composition. When it comes to the consideration of areas and area-systems, however, the subject of tone-relations becomes one of the greatest interest, because areas are defined and distinguished, not only by their outlines, but quite as much by differences of tone; that is to say, by tone-contrasts.