Have you ever heard someone say, Turn the light on I can't see a thing? Or: We'll have to wait until the sun rises before we can see? Without a light, we would be lost. A long time ago people depended upon the light of the sun to do their work. They would begin to work when the sun 

rose and would stop when the sun set. Then  people discovered fire and found that it could light rooms at night. You know the famous story about how Abe Lincoln used to read a great deal in front of his fireplace just to get the light from the fire. Of course many people used candles if they could afford them. Later a fuel kerosene was used in special lamps.