The white crystalline compound of sodium chloride (NaCl), known as common salt. There are in the earth vast underground deposits of rock salt, some several thousand feet thick. The oceans of the world contain about 2.7 percent sodium chloride in solution. This may seem to be very little, yet a cubic mile of seawater holds nearly 124 million tons of salt. The Dead Sea (Salt Sea) in Palestine is up to six times as salty. (Gen. 14:3) Salt was readily available to the Israelites. Evaporation of the Dead Sea waters furnished an ample supply, although of poor quality. There were salt-bearing hills near the southern end of the Dead Sea, not far from where Lot’s wife became a pillar of salt. (Gen. 19:26; Zeph. 2:9) Supplies of salt in northern Palestine may have come, at least partly, from the Phoenicians, who, it is said, obtained it by evaporation from the Mediterranean.
Notwithstanding such virtually inexhaustible supplies, salt has not always been readily available to man. Wars and revolutions have been fought for it. In ancient China salt was second to gold in value. Wives and children have been sold into slavery just for common salt. Caesar’s soldiers received part of their pay in salt, called salarium, from which comes the English word “salary.”—Compare Ezra 4:14.
The Bible takes note of salt as an essential part of man’s diet, as a seasoning for food. (Job 6:6) Under the Mosaic law anything offered on the altar to Jehovah had to be salted, not because of flavor, but doubtless because salt represented freedom from corruption or decay. (Lev. 2:11, 13; Ezek. 43:24) Large quantities of salt evidently were stored in the temple grounds for this purpose. Ezra saw to it that plenty was on hand for the sacrifices. (Ezra 6:9; 7:21, 22) It is reported that Antiochus III (c. 198 B.C.E.) gave 375 medimni (about 562 bushels or 20,000 liters) of salt to the temple service.
Certain healing, medicinal and antiseptic values are attributed to salt. Newborn babies were sometimes rubbed with salt at birth. (Ezek. 16:4) In limited quantities salt is beneficial on certain acid soils or when mixed with manure, but if allowed to accumulate in the soil, it kills vegetation and the land becomes barren and unfruitful, as was the case with the once-fertile Euphrates valley. A city condemned to total destruction was sometimes deliberately sown with salt, this act expressing the desire that the place be perpetually barren and sterile.—Deut. 29:22, 23; Judg. 9:45; Job 39:5, 6; Jer. 17:6.
Salt is often used in the Bible figuratively. Jesus told his disciples: “You are the salt of the earth,” a preserving influence on others, preventing spiritual putrefaction and moral decay. The good news they carried would preserve life. However, he went on to say to them: “but if the salt loses its strength, how will its saltness be restored? It is no longer usable for anything but to be thrown outside to be trampled on by men.” (Matt. 5:13; Mark 9:50; Luke 14:34, 35) One Bible commentator says on this: “The salt used in this country [United States] is a chemical compound—muriate of soda—and if the saltness were lost, or it were to lose its savour, there would be nothing remaining. It enters into the very nature of the substance. In eastern countries, however, the salt used was impure, mingled with vegetable and earthy substances; so that it might lose the whole of its saltness, and a considerable quantity of earthy matter remain. This was good for nothing except that it was used, as it is said, to place in paths, or walks, as we use gravel. This kind of salt is common still in that country. It is found in the earth in veins or layers, and when exposed to the sun and rain, loses its saltness entirely.”—Barnes’ Notes (1865) on Matthew 5:13.
Because salt prevented decay it became a symbol of stability and permanence. Often when covenants were made, the parties ate together—eating salt together—denoting perpetual loyalty and fidelity to one another in the covenant relationship. A “covenant of salt” therefore was considered very binding. (Num. 18:19) Accordingly, Judean King Abijah’s statement that Jehovah had made “a covenant of salt” with David and his sons meant that the covenant with David’s line for the kingship would stand forever. Jesus Christ the “son of David” and the “root of David” proves to be the one holding the Kingdom and administering its affairs forever.—2 Chron. 13:4, 5; Ps. 18:50; Matt. 1:1; Rev. 5:5; Isa. 9:6, 7.
Jesus said: “For everyone must be salted with fire” that is, purified and cleansed by Jehovah’s Word, which burns up all falsehood and error, and also by the fire of persecution, which tests and purifies one’s loyalty and devotion to Jehovah. (Jer. 20:8, 9; 23:29; Mark 9:49; 1 Pet. 1:6, 7; 4:12, 13) The apostle Paul said to Christians: “Let your utterance be always with graciousness, seasoned with salt, so as to know how you ought to give an answer to each one.” (Col. 4:6) One’s speech should always be in good taste, appetizing and having an appeal to its hearers, and should tend toward preserving the lives of those who heed it.