“A civilized life is impossible without salt” (Pliny, Nat. Hist. 31.41)
How was salt used in the ancient world?
Salt is an essential nutrient in the human diet. It allows our muscles and cells to function properly. The diet of a person living in the ancient Mediterranean region consisted of vegetables, breads, and occasionally meat. Salt does not naturally occur in these foods in sufficient quantities and was often added as a seasoning to make the food more flavorful. Salt was also used to preserve meat and to tan leather. Because of its versatility as both a condiment and preserver, salt became an important economic commodity from as early as 3,000 BCE. Salt was so important that the Roman army was provided a special salary (salarium) so that their soldiers could purchase salt (sal).
Salt was obtained in several ways (Pliny, Nat. Hist. 31.39). Salty seas and marshes were a common source. Salt water, collected in shallow pans or shallow ponds, evaporated, leaving behind the salt. Certain plants like seaweed and kelp were also common sources. Burning the plants and boiling the ash would leave behind a residue of salt. The Dead Sea in Palestine, also called the Salt Sea, provided a large amount of unrefined sea salt, which contained other minerals that needed to be removed through purification prior to human consumption. There were also salt quarries in the salty mountain on the Sea’s southwestern shore.
How is salt portrayed in the Bible?
There are more than thirty references to salt in the Hebrew Bible and the New Testament. In the Pentateuch salt is specified for grain offerings (Lev 2:13). The phrase “a covenant of salt” may refer to salt’s preservative ability: like salt, the covenant preserves the priesthood (Num 18:19) and the dynasty of David (2Chr 13:5). Alternatively this phrase could symbolize the communal meal. Elisha heals a spring of unwholesome water with salt (2Kgs 2:19-22). But salt could also render soil infertile (Judg 9:45) and so could symbolize judgment (Deut 29:22-23; Ps 107:33-34; see also Gen 19:25-26).
In the New Testament, salt is mentioned in all three synoptic gospels. Most famously in Matt 5:13, in the Sermon on the Mount, Jesus says to his disciples:
“You are the salt of the earth; but if salt has lost its taste, how can its saltiness be restored? It is no longer good for anything, but is thrown out and trampled under foot.”
Scholars debate the meaning of the puzzling phrase “salt of the earth.” A common interpretation is that Jesus is telling his disciples how they should act to flavor or preserve the world. The disciples exist for the good of others, not themselves. Otherwise they are useless, like flavorless salt.
The Greek phrase “salt of the earth” could also refer to an earthen oven, in which salt was used as a catalyst to burn fuel. Over time, the salt would no longer create the necessary chemical reaction and would be thrown out. By this reading, the disciples improve the world, not as a condiment, but as a catalyst: mixing fully into the world without being an agent of change would be a fundamental failure. Either way, the cultural importance of salt is key to the meaning of this verse: the disciples are like this precious commodity, which was critical for food preparation, preservation of meat and leather, and cooking.