The colors thus shown are the elementary colors of white light, commonly called the “primary” colors. The red, blue, and yellow are the most dominant in the spectrum, and in consequence always understood when we speak of “primary” colors; the intermediate rays shade into the various colors of the spectrum and are called “complimentary colors.” They show all the tints of the rainbow, which is in fact a gigantic solar spectrum.
The blade of grass has appropriated the red rays of the spectrum (or light) and leaves us only the blue and yellow, which, being reflected and blended, give us the sensation of green instead of white.
Every color affects the eye (or optic nerve) with a different vibration, which enables the optic nerve to inform the brain of the color. In this way we get the sensation of color. Black is the absence of all color; that is to say, it absorbs all the rays and returns none. White is the reflection of all the rays, none being absorbed.
The “primary colors,” red, blue, and yellow, have their “secondary colors,” which is the combination of any two primaries; as a mixture of blue and red make purple, the complementary (or contrast) of yellow, blue and yellow make green, which makes red the complementary or contrast. Yellow and red make orange, the complementary of blue. The secondary colors are therefore purple, green and orange.
The tertiary colors are those obtained by a mixture of all the primary colors (one proportion of which produces black), making what are called “broken tones.”
The “secondary colors,” produced as above, make the perfect contrast or complementary colors of the primary set, and the “tertiary colors,” or “broken tones,” produced as above, enable us to carry out harmony effects.
No harmony of color is perfect unless it contains all three primaries in some proportion or other. Thus, green (blue and yellow) and red are correct, having the three primaries in the composition. For simplicity I will not go into shades, which are simply lighter tints of the primary colors; but I may add that in harmony of color the color value or intensity of the shades must be carefully noted, to be effective; that is, a brilliant orange (red and yellow) will not be complementary to light blue, but would be correct with blue of same intensity. All the innumerable shades or tones are produced from the three primary colors, by reducing the strength of tint; that is, making it lighter, and the tones are produced by admixture of black, etc., or, rather, the admixture of the three primary colors, in different proportions, lowering the tone, and making lighter. Thus all the shades are made, each having its proper complementary color or contrast.
All colors, when brought into close proximity, affect each other by reflection or absorption, and the nearer they are in tone the more they will suffer. The difference in tone should be considerable, or a neutral line of black, white or gray placed between them; otherwise you have reds in proximity to blue appearing yellow, the complementary of red and blue. Red in proximity to green (its complementary) is purer and brighter. Red in proximity to black becomes duller. Red in proximity to white appears lighter (pink). Red in proximity to gray becomes brighter; so that the same red will appear of different shades according to its arrangement with regard to other colors adjacent. The same law governs the arrangement of all colors. If red and white are placed in contact, the white becomes tinged with the complementary of red (green), and the red appears deeper and brighter. White placed beside a color strengthens its tone. Black dulls it. Black surfaces appear faintly tinted with the complementary of the adjacent color, because of its low reflective power.
Black and white are commonly said to be complementary to each other, and to harmonize with all the other colors.