ration near the other
end, selects a darker bluish green dress, on which the trimming will be
less contrasted, while the hat appears brighter than before, because of
greater contrast.

(170) The variations of color sequence which can thus be studied out by
simple masks are almost endless; yet upon a measured system the
character of each effect is easily described, and, if need be, preserved
by a written record.

+Invention of color groups.+

(171) Experiments with variable masks for the selection of color
intervals, such as have been described, soon stimulate the imagination,
so that it conceives sequences through any part of the color solid. The
color image becomes a permanent mental adjunct. Five middle colors,
tempered with white and black, permit us to devise the greatest variety
of sequences, some light, others dark, some combining small difference
of chroma with large difference of hue, others uniting large intervals
of chroma with small intervals of hue, and so on through a well-nigh
inexhaustible series.

(172) As this constructive imagination gains power, the solid and its
charts may be laid aside. _We can now think color consecutively._ Each
color suggests its place in the system, and may be taken as a point of
departure for the invention of groups to carry out a desired relation.

(173) This selective mental process is helped by the score described in
the last chapter; and the quantity of each color chosen for the group is
easily indicated by a variable circle, drawn round the various points on
the diagram. Thus, in the case of the child's clothes, a large circle
around G 6/5 gives the area of that color as compared with smaller
circles around Y 8/7 and BG 4/3, representing the area of the straw and
the trimming.

(174) When the plotting of color groups has become instinctive from long
practice, it opens a wide field of color study. Take as illustration the
wings of butterflies or the many varieties of pansies. These fascinating
color schemes can be written with indications of area that record their
differences by a simple diagram. In the same way, rugs, tapestries,
mosaics,--whatever attracts by its beauty and harmony of color,--can be
recorded and studied in measured terms; and the mental process of
estimating hues, values, chromas, and areas by established scales must
lead the color sense to finer and finer perceptions.

The same process serves as well to record the most annoying and
inharmoniou