My Future's So Bright I Gotta Wear Sunglasses 4

Light can be easily taken for granted. The sun will rise and daytime will come. Lights are turned on to rooms. Candles are lit or flashlights turned on. Light is so vital to the human existence because it pushes the dark aside so we can see. There's another aspect of light that makes it so important. This is 4 of 4 in this series.