Color Theory and Light
GA 91
Lecture Two
3 August 1903, Berlin
When the Sun's rays are refracted by a prism and caught on an opposite wall, the circle of the Sun's disk is stretched in length, yielding at its edges all the colors of the solar spectrum from red to violet. This spectrum exerts a threefold effect: as heat, light and chemical effect. And it does so in such a way that red emits the most heat, which gradually decreases towards yellow. In the middle between yellow and green is the light band (the part with the strongest light effect). The blue shades, with purple being the strongest, produce chemical effects.
If rays pass through a glass sphere containing an alum solution, the spot of light obtained at the other end will probably shine, but will not give off heat, because the alum solution has absorbed it and let the light through.
Iodine dissolved in carbon disulfide would make the light spot appear as a dark spot, but one that contains heat and can ignite substances. Thus, this solution would have retained the light and given off the heat. This proves that matter is an entity endowed with determinate properties and freely attracts and repels.
A prism with rock salt solution or made of rock salt would show that the strongest heat emission still goes beyond the red, thus providing evidence that there are still other rays that we cannot perceive with our eyes. These invisible warmth rays are the infrared ones. Beyond the purple, the chemical effects still reveal invisible ultraviolet rays.
So a spectrum would be composed of these three different fields of forces. From one side, the warmth line, which decreases toward the center; and from there, the rise of the chemical force line, which is strongest in the ultraviolet. Into the center of both projects the line of light.
The eye perceives colors because it is constructed to produce colors. If the eye perceives a red object on a white background and now looks away, the same object will appear as the illusion of green on a white background. The eye that has seen red demands green. Yellow demands indigo, yellow-green demands violet. These colors that demand to be complemented are called complementary colors. They are colors that together make white—they demand each other.
An eye that cannot produce blue colors would see the forest as yellow, and violet would appear red to it.
Every color demands its counterpart, and complementary colors exert an aesthetic effect.