The sky is blue, the grass is green, the sun a burning yellow, but why? We know that white light is really a composite of the colors orange, yellow, green, blue, indigo and violet. The retina, which receives the light, contains three types of color sensors called red, green and blue cones. The red cones respond to the longer wave-lengths of light, the green cones to the middle range, and the blue cones to the short wave-lengths.

The brain has to juggle all of this different wave-length information and funnel it through the retina’s 5 million cones before we get a precisely painted picture of what our eyes have seen. This constantly changing stream of images from the world to our mind gives patterns of color at speed of light.

This amazing visual system works reliably in all but a tiny percent of the American population. When it does not, the result is color blindness.