(44) Lest this exact attitude in color study should seem inartistic, compared with the free and almost chaotic methods in use, let it be said that the stage thus far outlined is frankly disciplinary. It is somewhat dry and unattractive, just as the early musical training is fatiguing without inventive exercises. The child should be encouraged at each step to exercise his fancy. (45) Instead of cramping his outlook upon nature, it widens his grasp of color, and stores the memory with finer differences, supplying more material by which to express his sense of coloristic beauty. (46) Color harmony, as now treated, is a purely personal affair, difficult to refer to any clear principles or definite laws. The very terms by which it seeks expression are borrowed from music, and suggest vague analogies that fail when put to the test. Color needs a new set of expressive terms, appropriate to its qualities, before we can make an analysis as to the harmony or discord of our color sensations. (47) This need is supplied in the present system by measured CHARTS, and a NOTATION. Their very construction preserves the _balance of colors_, as will be shown in the next chapter, while the chapter on harmony (Chapter VII.) shows how harmonious pairs and triads of color may be found by MASKS with measured intervals. In fact, practice in the use of the charts supplies the imagination with scales and sequences of color quite as definite and quite as easily written as those sound intervals by which the musician conveys to others his sense of harmony. And, although in neither art can training alone make the artist, yet a technical grasp of these formal scales gives acquaintance with the full range of the instrument, and is indispensable to artistic expression. From these color scales each individual is free to choose combinations in accord with his feeling for color harmony. Let us make an outline of the course of color study traced in the preceding pages.[15] [Footnote 15: _See_ Part II., A Color System and Course of Study.] +PERCEPTION of color.+ (48) _Hue-difference._ Middle hues (5 principals). Middle hues (5 intermediates). Middle hues (10 placed in sequence as SCALE of HUE). _Value-difference._ Light, middle, and dark values (without change of hue). Light, middle, and dark values (traced with 5 principal hues). 10 values traced with each hue. SCALE of VALUE. _The Color Sphere_. _Chroma-difference._ Strong, middle, and weak chroma (without change of hue). Strong, middle and weak chroma (traced with three values without change of hue). Strong, middle, and weak chroma (traced with three values and ten hues). Maxima of color and their gradation to white, black, and gray. _The Color Tree._ +EXPRESSION of color.+ (49) _Matching and imitation_ of hues (using stuffs, crayons, and paints). _Matching and imitation_ of values and hues (using stuffs, crayons, and paints).