An Ancient Near-Eastern Understanding of Matthew 5:13 and the Salt of the Earth

Matthew 5:13 is one of the most well-known and popular passages in Scripture. Salt of the earth is a phrase in common usage in the English language, but the phrase’s meaning now has deviated from the original context in which Jesus first spoke it while teaching the crowds of ancient Judea. Currently, salt of the earth is used to reference hard-working common folk, those who support society from the background in their quiet virtuous way and who are underappreciated or just not often thought about. They are the backbone of society, or those who act as the glue, keeping the world together. But to properly understand what Jesus Himself meant in Matthew 5:13, along with related passages Mark 9:49–50 and Luke 14:34, one must use the Church’s tools for interpreting Scripture laid out in the Catechism, paragraphs 109–119. Using these instructions, and informed by Scripture, the Church Fathers, the orderly attributes of creation, and historical context, one can understand what it means to be the salt of the earth, and what is meant when Jesus says that this salt can lose its saltiness and may be thrown out.

Properties of Salt

To begin to understand what Jesus was speaking about, it may be useful to understand some physical properties of salt and what it was used for. A few terms are needed before trying to explain what salt does. Salt, most commonly sodium chloride (NaCl), is an electrolyte, which means that it not only dissolves in water, but also dissociates. When sugar is dissolved in water, it separates into individual particles of sugar and forms what is called a solution, thus distributing a sweet taste evenly in the water. When salt is dissolves in water, the sodium and chloride also dissociate, meaning they break into component ions which not only distribute throughout the water, but also allow the transmission of electricity through the water as the molecules and ions line up in ways that permit electrons to freely move through the solution.

Osmosis is the spontaneous passage or diffusion of water through a barrier which prevents the freedom of particles dissolved within the water. The electrolyte property of salt affects osmosis, important to biological processes because the way that ions diffuse is based on their concentration in water. This property of salt is important to biological function because the buildup of sodium ions is the process behind neural transmissions and muscle contraction. Salt’s ions are only permitted in certain amounts within biological systems, but because cells can control the flow of the ions and not the flow of the water, water flows from areas of low concentration of particles to high concentration of particles to equalize the distribution of the solutes. Where high amounts of salt are present with biological systems, because only a little salt is allowed within the cells, water is drawn out of cells, dehydrating the cells, sometimes enough to kill them. This property gives salt five primary uses and three subsequent associations in ancient societies: (1) salt as a seasoning, (2) salt as a preservative, (3) salt as a fertilizer, (4) salt as a cause of destruction or desolation, (5) salt as an antiseptic, (6) salt as a major valuable, (7) salt as a sign of favor, (8) salt used in covenant-making and sign of relationship.

Salt in the Time of Christ

Likely the first association Jesus would have had with salt, and likely one of the first things His audience would have recognized, is salt’s taste. Salt’s foremost use was as a seasoning, and it is this association that most modern people are familiar with. While salt is set alongside pepper on tables, their effects are not the same. Because salt is such an important substance for biological function, it is specifically built into the sense of taste as a flavor detectable by specific taste buds. It has an especially potent flavor, and yet salt’s primary use as a seasoning is to bring out the flavor of the food it is put on. There are a few different explanations for why salt enhances the flavors of foods instead of overriding them, but one main hypothesis is that salt induces diffusion, drawing out water and allowing the flavor particles to be less diluted and more pronounced. The other popular hypothesis is that the salt masks bitter tastes in food, allowing desirable sweet and savory flavor to be more pronounced.¹

The second common use of salt is preservation of food. In a time before refrigeration, food, and meat especially, still needed to be kept for extended periods of time without spoiling. The point of refrigeration is to keep microorganisms from spawning on and in the food making it inedible and dangerous to eat. This is a principle behind drying meat, smoking meat, and other methods of keeping meat. Of these, salt is just about the most ancient and this becomes a very prominent association of salt. While imperfect, salt is effective for this purpose. Most microorganisms are not very tolerant of salt. They have a weak ability to regulate the water in their bodies when salt is present beyond a certain extent, and if too much salt is present, they are killed, keeping the food safe for consumption. In Baruch 6:28, the wives of pagan priests are said to preserve the sacrifices of their husbands for later use. This passage is meant to demonstrate the uselessness of idols, but it also is an example of salt being used as a preservative.

Thirdly, salt has antiseptic properties which relate to the previously mentioned functions. By the same actions of osmosis which prevents unwanted growth on food, salt can prevent infection in wounds. Many ancients would use salt as an anti-septic because water would be drawn out of bacteria, killing them, drawing them out of the flesh, and so cleaning the area. It is commonly known that this is a very painful process, and it is such for a couple reasons. Firstly, besides drawing water out of the infectious organisms, salt also draws water out of the subject’s cells, drying them, which anyone with chapped lips or dry skin knows makes them more sensitive. Secondly, salt is not smooth, but jagged, and can itself cause some amount of damage to cell membranes. The ancients would have recognized the value of salt over the pain it would cause while being administered, but in modern usage, saline solutions are much more commonly used, being better at simultaneously washing out the wound and at not causing pain. A possible example of this kind of usage of salt in the Old Testament, at least symbolically, comes from 2 Kings 2:20. In this story, Elisha has just begun his ministry apart from Elijah and he comes to Jericho where the water source is bad and causes sickness and miscarriage. The leaders of the city plead with him, and in response he fills a bowl with salt and throws the salt in the water and cleanses it. It does not seem that Elisha would have had enough salt to truly purify a spring if it were infected by bacteria or fungi or other, and even if he did, it may not have been the most desirable water to drink from, but the symbolism is visible.

Fourthly, salt was used as a fertilizer in certain cases. In low amounts, salt can promote the growth of certain crops by killing weeds, thereby reducing competition. There is a fine line for this to work, between the killing of the weeds and the killing of the crops, and only certain salt-resistant crops, like asparagus, cauliflower, or cotton, really benefit from this kind of fertilizer. Salt can even promote the release of minerals in soil. A second fertilizing application of salt relates more to salt’s preservative properties when salt is applied to manure. Salt, again in low amounts, can keep manure from rotting if left to sit for a time before being spread in fields.

From the fifth association of salt is derived a somewhat popular idiom: “salting the earth.” It refers to stories where, after victory over an enemy, an invading army would spread salt on the fields around the loser’s city, rendering the fields useless and infertile. This both symbolizes and actualizes curse upon the land and the inhabitants who would face hardship without productive land and would likely have to leave. This is, of course, the message behind the Romans salting Carthage. They hated Carthage so much that they wanted it never to return to power. Another very ancient example of this, specifically with implications of divine judgement, comes from the eighth-century Sefire Treaty steles.² In section III on curses with accompanying rites, there is found the line “and may Hadad sow in them salt.” Them refers to Arpad and subject cities who are the subjects of this treaty with KTK. This treaty invokes divine judgement from the god, Hadad, upon Arpad in response to any potential unfaithfulness to the treaty. This appears to have been part of a common formula for covenant curses in ancient Mesopotamia as another similar inscription exists in Bukān, Iran.³ A Biblical example of this is found in Judges 9 when Abimelech, who had previously become king of Shechem by an act of treachery, was at war against his own city which was led by Gaal the son of Ebed. He defeated Shechem and amidst other violences against it, he sowed it with salt (Judges 9:45). There is debate about whether salting the earth was an actual tactic used by the ancients. For the high cost of throwing away salt, this wouldn’t be a particularly effective method. Salt can be easily washed away by rain, so the fields would likely be usable again before long, resulting only in a period of hardship. Besides this, the salting of Carthage is likely an apocryphal tale. Related to man salting the earth, one euphemism for a wasteland was a salt land because soil with a high concentration of salt is infertile. Thus, areas like the Dead Sea are not lively places, but desolate lands. In several passages of prophecy and song, there are imagery referring to the unrighteous losing their prosperity and becoming “as a wasteland” or his land to become a salt land. These are areas or people forsaken by God.

As a result of these properties, salt in the ancient world was an important commodity and contributed heavily to the wealth of a region. As societies grew to be more agriculturally dependent, salt became more important for trade and primitive industry as many immediate sources of salt fell short of the needed yield for large stationary populations.⁴ Examples such as Timbuktu and other medieval African cities trading salt for gold at high rates show that salt was on par with precious metals in certain times and places where it was harder to get. Just because salt was hard to come by at times did not mean that people were willing to go without. Indeed, they could not have survived such deprivation. In Italy, the famous Via Salaria is an ancient salt route in Italy with origins much older than Rome itself. It may have played a vital role in circumstances allowing the rise of Rome and soldiers of Rome were often paid in salt rather than money. This is where the word “salary” comes from. In 1 Maccabees, the king Demetrius shows Judea favor by releasing them from a salt tax (1 Macc 10:29, 11:35). Salt, then, was of vital importance economically to the ancients.

Salt was also used as a sign of favor in the ancient world. Because of its great value, it was a generous gift to those with which one wanted to be friendly with. In the Book of Ezra, the enemies of the Jews write to King Artaxerxes and in that letter, they describe how the Jews “eat the salt of the palace” (Ezra 4:14). The meaning of this phrase is that the Jews were living off the wealth of the king, literally subsidized by the wealth of the empire. This policy had originated from Cyrus the Great as was later uncovered, and it was a sort of favor upon the Jews and a symbol of his special relationship with them. When this was uncovered, the supplies were once again sent to the Jews, but in the passage describing this event — Ezra 7:22 — while certain large amounts of silver, wheat, oil, and wine, were sent to the Jews, salt was to be supplied in unlimited quantity.

Salt was used to represent relationships in the ancient world, and most importantly, covenants. In Nicomachean Ethics, in chapter 8, on friendship, Aristotle uses a phrase about sharing a “proper amount of salt” with a friend. This idea would have come from Athens to Judea with the Hellenistic culture spread by Alexander the Great, student of Aristotle, but in the context of the middle East, it would have been a shallower interpretation of sharing salt because such a phrase was already used in Mesopotamia. In Akkadian, the phrase tabat X lehemum means to eat the salt of another person,⁵ but it also was used in the ancient context to mean making a covenant. Ancient peoples often made covenants in connection with a meal, because people in relationship eat together peacefully. In certain contexts, sacrifices, covenant-making, and eating were all intertwined. Baruch 6:28 references sacrifice being made, but the eating of the sacrifice, or perhaps the sale of the sacrificial meat, being done without connection. In the case of the Jews, the priests were specifically instructed to eat from the offerings, and this was called “a covenant of salt for ever” (Num 18:19). The Jews had an extensive theology on this topic. From all the aforementioned attributes, salt was recognized by the Jews to be a very fitting sign of their covenant theology.

Salt to the Jews and in the Old Testament

The Jews used salt in mostly the same ways that other ancient peoples did, but they expanded on the symbolism of salt, and salt is mentioned extensively in the Hebrew Old Testament with several references to The Salt of the Covenant. Leviticus instructs that every cereal offering must be seasoned with salt and states, “You shall not let the salt of the covenant with your God be lacking from your cereal offering” (Lev 2:13). But why is salt in every cereal or grain offering? A careful study of the attributes of salt described above reveals how salt is a perfect sign to represent covenant-making under God. Salt is appropriate for the covenant in its antiseptic properties. Ever since the fall, because man broke his relationship with God and so cut himself off from the tree of life (Gen 3:22), he has been in need of a preservative to keep his life. Just as salt heals infection, covenant with God is understood to preserve spiritual life, keeping corruption and the infection of sinful lifestyles at bay. Because salt keeps food fresh, it became a symbol of permanence just as God’s covenant is made to last forever. At the same time, being unfaithful to the covenant causes the reverse: corruption permeates society and sin infects the people; life is destroyed. This is described in Deuteronomy 28, on covenant blessings and curses, and the rest of the Old Testament is the story of this cyclic occurrence.

Furthermore, the priests were instructed to eat of the cereal offering. The priests, being representatives for the people, were to eat a covenantal meal with God from the sacrifice being offered. Thus, when the priests ate of the covenantal meal with God, it was what Aristotle described as friends sharing the proper amount of salt over a meal.⁶ Furthermore, as salt could be used in certain cases as fertilizer, specifically by killing less salt-resistant weeds and promoting the release of minerals into the soil, so does the covenant act. Living according to the covenant drives out the sin and temptation which inhibits growth and promotes the release of virtue into the environment which promotes the growth of the people. But, to a people living contrary to the terms of the covenant, the effects of the covenant would be curse. Similarly, salt could be used to destroy the soil, rendering it infertile, but it would wash out in time and allow the return of life to the land after a period of trial and purification. It is with this understanding that Jesus spoke to the people in Matthew 5:13, and the covenant curses, further explored, may help explain what Jesus meant when He said that salt may lose its savor.

How Might Salt Lose Its Saltiness?

Matthew 5:13 contains the confusing clause, “but if salt has lost its taste, how shall its saltiness be restored?” One might question how salt could lose its taste or stop tasting like salt. Obviously, table salt does not lose its taste under normal circumstances. Typically, it is only when salt disappears that its saltiness goes away. It is possible that Jesus was simply speaking hypothetically or hyperbolically, but there is also a phenomena that Jesus may have been literally referencing here — a real way in which salt can lose its taste without disappearing. In fact, this interpretation is quite likely. In either case, it is not reasonable to think that Jesus was literally speaking of regular salt which would decompose, because NaCl is a stable compound which, if anything, is merely washed away and leaves no residue. Eugene P. Deatrick⁷ in 1962 reports this phenomenon that explains how rock salt in Israel may become less salty. According to Jacob Freedman, gypsum dust from the Jordan River Valley may be windblown into Jewish Palestine, polluting the rock salt of the area and rendering it less salty. Another detail Deatrick mentions is that modern Israeli shepherds regard rock salt as salt of the earth and sea salt as salt of the sea, further evidencing that Jesus was specifically referring to rock salt in his metaphor. It is this rock salt — the salt of the earth — that Jews would crush up and use for their food and which was contaminated by gypsum.

To Whom Was Jesus Speaking?

Knowing what salt meant in Jesus’ context is only useful when considering the intended recipients of the metaphor, because people in different roles receive unique instructions from this phrase according to their positions. Matthew 5:13 is at the beginning of the Sermon on the Mount where a large audience was there to hear the preaching, but the text in Matthew does not actually make it clear who He was speaking to. This does, in fact, play a great deal of importance: “Seeing the crowds, he went up on the mountain, and when he sat down his disciples came to him. And he opened his mouth and taught them” (Mt 5:1–2, emphasis added). Now it isn’t entirely clear, but it appears from this passage at the beginning of the Sermon on the Mount that Jesus is speaking to his disciples. This is similar to Mark 9:49 when Jesus is speaking in a house to his disciples, and that passage is somewhat clearer on this fact. If such is the case, then this could be interpreted in light of the priestly role of the inner circle of Jesus’ disciples, those who would later become the Apostles. They of course would have a particular leadership within the Church and in the world, and it is perhaps these who ought to be called the salt of the earth, mediators of the new covenant.⁸ This is one way in which St. Jerome and perhaps St. John Chrysostom interpret this passage.⁹ Essentially, this would mean that the metaphor is referring to the Church’s entity.¹⁰

However, at the end of the Sermon on the Mount is this passage: “And when Jesus finished these sayings, the crowds were astonished at his teaching” (Mt 7:28). So clearly, the crowds were at least listening in on what Jesus was telling his disciples. And in Luke 14:34–35, Jesus is explicitly said to have turned from those at table to whom he was primarily speaking, to the crowds looking intrusively in on the meal. Now these three passages seem to be describing different events, one being on the Mount, another in Capernaum, and another near or in Jerusalem, and while Matthew and Mark only explicitly report Jesus speaking to His disciples, Matthew and Luke both give reason to believe Jesus was speaking to the crowds too, either directly or indirectly. But Matthew’s is the only Gospel in which Jesus specifically makes that statement “you are the salt . . .”

The most straightforward interpretation of the text would be that Jesus is telling his disciples that they are the salt of the earth, and not telling the masses, but this does not require that Jesus is only instructing the clergy. Firstly, the first list of the Twelve doesn’t come until five chapters later in Matthew’s Gospel: this is quite early in Jesus’ ministry. Secondly, there are two adjacent passages that may inform the reader of another audience. The Beatitudes come immediately before, and the “light of the world” metaphor comes immediately after. The Beatitudes clearly describe those who are followers of Jesus, those who are his disciples, but they are also obviously not restricted to the Twelve (who are not a set group yet). “Blessed are the poor in spirit” (Mt 5:3): the poor in spirit is a group attainable by all those who follow Jesus. The Jerome Biblical Commentary,¹¹ among others, makes the direct connection between the passages of salt and of light: “The explanation of the two images (5:16) refers [the images] to the “good works” of the disciples.” Later in the sermon, Jesus similarly explains who will be saved as “he who does the will of my Father who is in heaven” (Mt 7:21).

So, the words of Jesus and the interpretation of scholars seems to point to an audience that is wider than the Twelve and the clergy, but narrower than the crowd, designated as “disciples,” or those who “manifest the goodness of “their Father in heaven” by living according to the teaching of Jesus. This means that Jesus is speaking to those who are called to a mission to go on and further teach the crowds, a group which includes all Christians. Historically, the Church promotes a “both/and” option in such situations, and any reductionist interpretation would be contrary to the truth. Hence, it would appear that Jesus is speaking this message both to the Twelve, and so the Church in her formality, as well as to this wider group of disciples, those who make up the Church. The work to which Jesus calls his audience is to be in individuals as well as for the culture at large.

Spiritual Implications for Christians as Salt

Upon study of the numerous contexts in which salt could be used in the ancient world, the most comprehensive look at the history and of the Biblical context reveals a covenantal meaning to the phrase “the salt of the earth.” When Jesus tells his followers that they are to be “the salt of the earth,” he is instructing them to be like spiritual salt, which is suitable for use in bringing out the true and good character of the world, for promoting spiritual growth and destroying spiritual and societal pollution, and for preserving the world for a glorious final destiny. Because of these attributes, salt is not just good for menial tasks, but suitable for signifying relationship and for a noble gift. Then even more, it is suitable for signifying covenant, particularly God’s covenant with His people. Christ’s followers, now Christians, are to bring the world back into covenant fidelity by their works which “shine before men . . . and give glory to [their] Father who is in heaven” (Mt 5:16).

The fundamental meaning of the call to be the salt of the earth is to be a saint. In every generation, when the world looked to be falling apart, great saints rose up to revive the faith, bringing it back from seeming death. We are all called to be saints, though not everyone is called to be a preacher or a large-scale reformer. Most of us are called to be saints on a more proximate scale by following our vocations with great love and heroic virtue. Saints are the salt of the earth because it is their work that brings the world into union, or Covenant fidelity, with God and by them the world is blessed. It is a participation in Christ’s sacrifice as enabled by the transformative power of grace which allows even our small works to be effective. Covenant living preserves life, ending the corruption of fallen matter and killing sin which infects our lives. It encourages spiritual development by the inhibition of evil habits. The disciple is a gift to the world, a gift of God’s grace and a sign of His favor, a gift that He gives freely and without restriction. And rather than causing uniformity and simply covering over the unique persons and cultures in the world, covenant living brings out the true person as a fuller expression of who he or she is. On the contrary, when people depart from Covenant living, and when the Christians fall away from their mission, infertility necessarily occurs, and so God’s gifts become curses, and the society becomes desolate and debased.

Salt, then, as used in Jesus’ metaphor, is just about the most comprehensive piece of imagery that describes Christians. When Jesus tells his followers (and by extension, us), “You are the salt of the earth,” he is revealing the spiritual reality of the Church as a sign of God’s covenantal love. But He is not merely revealing this aspect of the Church in her institutional form. He is instead revealing this to the Church as her members. Matthew 5:13 is a concise description of the mission that we, as members of the body of Christ, are sent out for. Therefore, Matthew 5:13 is not just a description of us as the salt of the earth, but a mandate to be the salt of the earth — to preserve, enhance, and heal the culture. The Church is the means by which virtue is drawn out in society and the means by which sin dies. We are a gift to the world from God if only we will remain pure, undefiled by the pollution of the world we are given to. All this Jesus says by the few words, backed by a great deal of providence in nature, “You are the salt of the earth.”