A city that is set on an hill cannot be hid. Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven. Salt penetrates, light exposes. Salt hinders the spread of corruption. Salt creates thirst.
Salt brings out the flavor.
If salt ever loses its flavor there is no way to restore the true natural taste. Jesus is the source of the light, Christians are the reflection of His light. As the moon reflects the glory of the sun. We Christians are to reflect the glory of the Son on a lost and dying world. We elevated above our surroundings, a city that is set on hill cannot be hid.