riads: the major, the minor, the augmented, the diminished,
and the altered. The major triad consists of the first note of the
diatonic scale, or tonic; its third, and its fifth. The minor triad
differs from the major only in that the second member is lowered a
semi-tone. The augmented triad differs from the major only in that the
third member is raised a semi-tone. The diminished triad differs from
the minor only in that the third member is lowered a semi-tone. The
altered triad is a chord different by a semi-tone from any of the
above.

The major triad in color is formed by taking any one of the twelve
color-centers of the ophthalmic color scale as the first member of
the triad; and, reading up the scale, the fifth step (each step
representing a semi-tone) determines the second member, while the
third member is found in the eighth step. The minor triad in color is
formed by lowering the second member of the major triad one step; the
augmented triad by raising the third member of the major triad one
step, and the diminished triad by lowering the third member of the
minor triad one step.

[Illustration: Figure 18. MAJOR TRIAD, MINOR TRIAD, AUGMENTED TRIAD,
DIMINISHED TRIAD]

These various triads are shown graphically in Figure 18 as
triangles within a circle divided into twelve equal parts, each part
representing a semi-tone of the chromatic scale. It is seen at a
glance that in every case each triad has one of its notes (an apex) in
or immediately adjacent to a different one of the grand divisions of
the colour scale hereinbefore established and described, and that the
same thing would be true in any "key": that is, by any variation of
the point of departure.

This certainly satisfies the mind in that it suggests variety in
unity, balance, completeness, and in the actual portrayal, in color,
of these chords in any "key" this judgment is confirmed by the eye,
provided that the colors have been thrown into proper _harmonic
suppression_. By this is meant such an adjustment of relative values,
or such an establishment of relative proportions as will produce the
maximum of beauty of which any given combination is capable. This
matter imperatively demands an aesthetic sense the most sensitive.

So this "musical parallel," interesting and reasonable as it is, will
not carry the color harmonist very far, and if followed too literally
it is even likely to hamper him in the higher reaches of his art,
for some of the music