of blue, blue-violet, violet and purple. The merging of purple into purple-red will then correspond to the meeting place of the highest with the lowest, "spirit" and "matter." We conceive of this meeting-place symbolically as the "heart"--the vital centre. Now "sanguine" is the appropriate name associated with the color of the blood--a color between purple and purple-red. It is logical, therefore, to regard this point in our color-scale as its tonic--"middle C"--though each color, just as in music each note, is itself the tonic of a scale of its own. Mr. Louis Wilson--the author of the above "ophthalmic color scale" makes the same affiliation between sanguine, or blood color, and middle C, led thereto by scientific reasons entirely unassociated with symbolism. He has omitted orange-yellow and violet-purple; this makes the scale conform more exactly with the diatonic scale of two tetra-chords; it also gives a greater range of purples, a color indispensable to the artist. Moreover, in the scale as it stands, each color is exactly opposite its true spectral complementary. The color scale being thus established and broadly divided, the next step is to find how well it justifies itself in practice. The most direct way would be to translate the musical chords recognized and dealt with in the science of harmony into their corresponding color combinations. For the benefit of such readers as have no knowledge of musical harmony it should be said that the entire science of harmony is based upon the _triad_, or chord of three notes, and that there are various kinds of triads: 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]