Hold a quartz prism up to the sun on a clear day. As you do this the light refracts within the crystal and shines a small rainbow on a target surface. By doing this simple experiment we may observe the individual elements of the sunlight, from red, orange, yellow, green, and all the way to violet. (See figure 1.1) Through closer inspection one could pinpoint the most pure concentrations of each colour on this rainbow—the brightest blue, the healthiest green, the most vibrant orange. Between each of these points the colours mix, giving way to shades of yellow-green, indigo-blue, orange-red, and the like, fading in and out as they move from one concentrated area to the next.