Salt is a mineral extracted from the ground, or taken from the sea by evaporation, which is used to give flavour to food (see Job 6:6). It is a preservative, enabling meat and other foods to be kept for long periods, and also a basic antiseptic (see Ezekiel 16:4). All these qualities were known and used extensively in Bible times.

Salt is also given a spiritual significance. Under the Law of Moses grain offerings were to be seasoned with salt, to indicate that the offerer was making his offering in sincerity and in the right spirit.

Jesus tells his disciples "you are the salt of the earth" (Matthew 5:13), meaning that the guidance and example they would give to the world could prevent human civilisations becoming altogether tasteless and corrupt. Jesus also warned them that they were not to lose their 'saltiness' by neglecting the preaching of the gospel. If they did, they, and the world they were influencing would become altogether useless.