Like salt, light is something that can have a dramatic effect on everything it touches. Light makes it possible to see. A lighthouse warns ships of the coastline; emergency lights warn drivers of a high-speed vehicle. Light speaks of security and reassurance. When we are in a dark house and hear an unfamiliar noise, we instinctively turn on a light because we want to be able to see and be seen. Jesus says we are to be like that to a neighborhood that dwells in darkness.