The command "Let there be light" was the beginning of creation, and all created life has found it "was good." Plants and animals transform the force of the sun's rays into food and life. The human race, in all languages, has used light to interpret joy, hope, intelligence, information, truth. The contrast of light and darkness explains the contrast of good and evil.
Each day in the past winter I have watched the children running to school, shouting to one another, happy to greet one another, to get together for a few minutes outdoors on the playground. It seemed so different from Shakespeare's picture of "the schoolboy with shining morning face, creeping like a snail, unwillingly to school." There seemed no reason for this contrast except that the playground was out in the sunlight and the schoolroom was in comparative darkness. Perhaps the schoolrooms were even worse in Shakespeare's time