Matthew 5:13-16 - The Sermon On The Mount: Salt And Light
13 "You people are [like] salt on the earth. But if salt loses its flavoring ability, how will it ever get it back again? From then on it would be good for nothing except to be thrown out onto the roadway and walked on by people. [Note: This was mined salt which, when losing its "saltiness" due to exposure to the sun or rain, was simply disposed of by being dumped onto the roadway where people walked].
14 You people are [like] light in the world. A city built on a hill will not go unnoticed. 15 Neither does a person light an [olive oil] lamp and place it under a bushel-sized container, but on a stand where it can illuminate everything in the house. 16 In that same way, you should allow your light [i.e., influence] to shine in front of people, so that they will see your good deeds and [be led to] honor your Father in heaven.