"You are like salt for all mankind. But if salt loses its saltiness, there is no way to make it salty again. It has become worthless, so it is thrown out and people trample on it.
You are like light for the whole world. A city built on a hill cannot be hidden. No one lights a lamp and puts it under a bowl; instead he put it on the lamp stand, where it gives light for everyone in the house. In the same way your light must shine before people, so that they will see the thing you do and praise your Father in heaven."
Mark 9.50 : Luke 14.34-35