The Science Behind Salt Losing Its Saltiness
Decrypting Matthew 5:13
This article is focused on a metaphor found in both Matthew and Luke.
13 “You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled by men. (Mat 5:13 NIV)
The version in Luke is a close parallel.
34 “Salt is good, but if it loses its saltiness, how can it be made salty again? 35 It is fit neither for the soil nor for the manure pile; it is thrown out. “He who has ears to hear, let him hear.” (Luk 14:34–35 NIV)
Notice that in Luke the verse ends with the admonishment, “He who has ears to hear, let him hear.” This synoptic marker clearly indicates that there is more to this verse than is readily apparent. Another indicator is the chemical impossibility at its heart.
Simply put, salt cannot lose its flavor. There have been several arguments put forth over the years. Some have pointed out that Jesus was a moral philosopher and not a chemist. Others have suggested that the impossibility was the point. Just as it was against nature for salt to lose its flavor so too was it against the will of God that a disciple could lose his faith.
The most common explanation is that during the time of Jesus, salt was quite impure, containing a variety of other substances. If this compound got wet, the actual salt would be washed away, leaving a powdery substance lacking saltiness.
So basically three explanations. The first is that Jesus wasn’t a chemist. The second is that Jesus understood the impossibility of salt losing its flavor and that that was part of the point he was trying to make. The third option is that people in the time of Jesus had access to poor-quality salt mixed basically with dirt.
My own view is that the creator of these verses understood chemistry quite well. In fact, these verses were designed as a puzzle that could only be solved by someone with a fair amount of chemical knowledge themselves.
First, we must analyze the verses we have. Salt that has lost its flavor is thrown out and trampled by men according to Matthew. In Luke, it is not good for either the soil or the dungheap.
This bit about a dungheap reminds me of a similar saying from the Gospel of Thomas.
(93) <JESUS said>, ‘Do not give holy things to dogs, lest they throw them upon the dunghill. Do not throw pearls to swine lest they [. . .].”¹
This is, of course, a parallel to the verses from Matthew concerning pearls and where not to cast them.
6 “Do not give dogs what is sacred; do not throw your pearls to pigs. If you do, they may trample them under their feet, and then turn and tear you to pieces. (Mat 7:6 NIV)
Okay, at the risk of repeating myself, let me set the evidence out as clearly as possible. Matthew 7:6, above, tells us that if we cast our pearls to pigs that they, the pigs, will trample them. Matthew 5:13, below, also tells us that salt that has lost its saltiness will be trampled by men.
13 “You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled by men. (Mat 5:13 NIV)
Then we turn to the Gospel of Thomas, where we are told not to give holy things to dogs because they will throw them on a dunghill.
(93) <JESUS said>, ‘Do not give holy things to dogs, lest they throw them upon the dunghill. Do not throw pearls to swine lest they [. . .].”²
This saying matches up with Luke’s version of salt lacking saltiness.
34 Salt is good: but if the salt have lost his savour, wherewith shall it be seasoned? 35 It is neither fit for the land, nor yet for the dunghill; but men cast it out. He that hath ears to hear, let him hear. (Luk 14:34–35 KJV)
The parallels are clear. The texts indicate, in a veiled manner, that pearls thrown before pigs are somehow connected to salt lacking saltiness.
This is where chemistry gets involved. Let’s consider a pig trampling on a pearl. Let us suppose that it completely crushes a pearl down to powder.
This powder would be composed of the chemical calcium carbonate (CaCO³). More importantly for our research, chemically, calcium carbonate is a salt. However, it doesn’t taste like sodium chloride (NaCl), but more like chalk, because that is essentially what it is. It is a salt lacking saltiness.
Here, the key to the puzzle hinges on the double meaning attached to the word salt, which in one case refers to sodium chloride, while in the other, according to Oxford Languages, it indicates “any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation.”
Do not cast your pearls before pigs or fools because they will trample them and turn them into a salt lacking saltiness.
Okay, so let's take it as a given that when the text mentions a salt lacking saltiness it is implicitly referring to pearls. What does that tell us?
In the case of Matthew 5:13, it doesn’t really convey any special information as this verse is just the first in a series of metaphors from the Sermon on the Mount.
In Luke, however, we find the verse at the conclusion of the Parable of Counting the Cost, where it seems that the addition of pearls might have greater significance than it first appears.
28 “Suppose one of you wants to build a tower. Will he not first sit down and estimate the cost to see if he has enough money to complete it? 29 For if he lays the foundation and is not able to finish it, everyone who sees it will ridicule him, 30 saying, ‘This fellow began to build and was not able to finish.’ 31 “Or suppose a king is about to go to war against another king. Will he not first sit down and consider whether he is able with ten thousand men to oppose the one coming against him with twenty thousand? 32 If he is not able, he will send a delegation while the other is still a long way off and will ask for terms of peace. 33 In the same way, any of you who does not give up everything he has cannot be my disciple. 34 “Salt is good, but if it loses its saltiness, how can it be made salty again? 35 It is fit neither for the soil nor for the manure pile; it is thrown out. “He who has ears to hear, let him hear.” (Luk 14:28–35 NIV)
We will consider this matter more thoroughly in a future article.
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