alances darker blue-green. Middle red balances
middle blue-green. In short, every straight line through this centre
indicates opposite qualities that balance one another. The color points
so found are said to be "_complementary_," for each supplies what is
needed to complement or balance the other in hue, value, and chroma.

(77) The true complement of the buttercup, then, is not the violet,
which is too weak in chroma to balance its strong opposite. We have no
blue flower that can equal the chroma of the buttercup. Some other means
must be found to produce a balance. One way is to use more of the weaker
color. Thus we can make a bunch of buttercups and violets, using twice
as many of the latter, so that the eye sees an _area_ of blue twice as
great as the _area_ of yellow-red. Area as a compensation for
inequalities of hue, value, and chroma will be further described under
the harmony of color in Chapter VII.

(78) But, before leaving this illustration of the buttercup and violet,
it is well to consider another color path connecting them which does not
pass through the sphere, _but around it_ (Fig. 12). Such a path swinging
around from yellow-red to blue slants downward in value, and passes
through yellow, green-yellow, green, and blue-green, tracing a _sequence
of hue_, of which each step is less chromatic than its predecessor.

[Illustration: Fig. 12.]

This diminishing sequence is easily written thus,--YR 8/9, Y 7/8,
GY 6/7, G 5/6, BG 4/5, B 3/4,--and is shown graphically in Fig. 12. Its
hue sequence is described by the initials YR, Y, GY, G, BG, and B. Its
value-sequence appears in the upper numerals, 8, 7, 6, 5, 4, and 3,
while the chroma-sequence is included in the lower numerals, 9, 8, 7, 6,
5, and 4. This gives a complete statement of the sequence, defining its
peculiarity, that at each change of hue there is a regular decrease of
value and chroma. Nature seems to be partial to this sequence,
constantly reiterating it in yellow flowers with their darker green
leaves and underlying shadows. In spring time she may contract its
range, making the blue more green and the yellow less red, but in autumn
she seems to widen the range, presenting strong contrasts of yellow-red
and purple-blue.

(79) Every day she plays upon the values of this sequence, from the
strong contrasts of light and shadow at noon to the hardly perceptible
differences at twilight. The chroma of this sequence expands during the
summer to st