Light is a form of energy that takes the shape of magnetic or electrical waves, and these waves are reflected off of or emitted from matter (Dictionary.com's 21st Century Lexicon). According to Sir Isaac Newton's theory of light and color, since these waves of light have different frequencies and wavelengths, once reflected off of or emitted from matter, these waves appear as colors. Newton developed the theory because he saw that when light passed through a prism, light broke up into seven different colors of different wavelengths: red, orange, yellow, green, blue, indigo, and violet. Newton further saw that all colors were really a combination of these seven different colors and, therefore, a combination of different light wavelengths ("Isaac Newton: 1642 - 1727," Wichita State University). There are different theories that work together to explain how we see color. According to the Young-Helmholtz theory, also called the trichromatic theory, we are able to see color because the retinas of our eyes are formed with three types of cones that are sensitive to the wavelengths of the three colors; red, green and blue ("Theories of Color Vision," University of Calgary). Therefore, the difference between light and color is that light is energy made up of wavelengths, whereas colors are the various wavelengths our eyes are sensitive to and can see once the light is reflected from or emitted from matter. Light and color are dominant recurring motifs in Jeanne DuPrau's The City of Ember. As the characters achieve enlightenment by making their way out of Ember, the more they witness brighter light and more color.
The recurring motif of light is first developed when the narrator explains that Ember is surrounded in darkness, and the only light the citizens of Ember have is electric. As the story develops, the reader learns that the citizens are running out of light bulbs, and their power generator is beginning to fail.
The motif of color is developed throughout as the narrator describes various colors such as the red of Lina's messenger jacket. But what is most interesting is the description that Ember's most dominant colors are black and gray: "gray buildings, gray streets, black sky" (Ch. 5). Lina rebels against her drab, colorless surroundings by buying very expensive, black market colored pencils, a moment that further develops the recurring color motif.
The recurring color motif reaches its greatest intensity the moment Doon and Lina see the brightest colors they have ever seen in their lives when they experience the first sunrise after having emerged from Ember. Not knowing what the sun is, they think of it as a light. And, they note that as the light rises higher into the sky, "The color seeped out of the sky and washed over the land ... every shade of green sprang to life around them" (Ch. 19).