Salt and light are both elements with which everyone is familiar. They are essential to life. In the ancient middle east salt was sometimes added to fuel for cooking. Dried animal dung with added salt was shaped into fuel cakes, used in outdoor 'earth' ovens. The salt acted as a catalyst to help the dung catch fire quicker and burn brighter.
Was this something familiar to Jesus I wonder? In the Sermon on the Mount he tells his disciples, "you are the salt of the earth" (Matthew 5: 13). Was he thinking of salt as preservative? Or as the means of bringing out the flavour in food? Or salt as symbol of a covenant? Or was it also the dung-salt cakes for the earth ovens, the remains of which would be "thrown out and trampled under foot"?
Perhaps all those things, but I rather like the salt in the cooking fuel idea, as it links with what Jesus said next, "you are the light of the world". So, for a community to be the salt of the earth is to help light and warm the fire of love for God and neighbour. What do you think?