Let your speech be always with grace, seasoned with salt,
that ye may know how ye ought to answer every man.
(Bible, Colossians, chapter IV, verse 6)
Salt's ability to preserve food was a foundation of civilization. It eliminated the dependence on the seasonal availability of food and it allowed travel over long distances. It was also a desirable food seasoning. However, salt was difficult to obtain, and so it was a highly valued trade item, which followed the pull of economics along salt roads such as the Via Salaria in Italy, some of which had been established in the Bronze Age. Until the twentieth century, salt was one of the prime movers of national economies and wars.
Today, salt is almost universally accessible, relatively cheap and often iodized.
Salt in Antiquity and Middle Ages
It is commonly believed that Roman soldiers were at certain times paid with salt. This, however, is a misconception: 'salary' derives from the Latin word salārium, meaning money given to soldiers so they could buy salt. The Roman Republic and Empire controlled the price of salt, increasing it to raise money for wars, or lowering it to be sure that the poorest citizens could easily afford this important part of the diet. It was also of high value to the Hebrews, Greeks, the Chinese and other peoples of antiquity.
Already in the early years of the Roman Republic, with the growth of the city of Rome, roads were built to make transportation of salt to the capital city easier. An example was the Via Salaria (originally a Sabine trail), leading from Rome to the Adriatic Sea. The Adriatic Sea, having a high salinity due to its shallow depth, had more productive solar ponds compared with those of the Tyrrhenian Sea, much closer to Rome.
During the late Roman Empire and throughout the Middle Ages salt was a precious commodity carried along the salt roads into the heartland of the Germanic tribes. Caravans consisting of as many as forty thousand camels traversed four hundred miles of the Sahara bearing salt to inland markets in the Sahel, sometimes trading salt for slaves: Timbuktu was a huge salt and slave market.
In the New Testament, Matthew 5:13 Jesus said, "You are the salt of the earth." He added that if the salt loses its flavor, it is good for nothing but to be trampled. Jesus said this in order to show his disciples how valuable they were and this saying is commonly used today to describe someone who is of particular value to society. In addition, the preservative quality of salt is in view here to show how the disciples were called to preserve the society and the world around them from moral decay. On another occasion according to the Gospels, Jesus commanded his followers to "have salt within them".
Cities and wars
Salt has played a prominent role in determining the power and location of the world's great cities. Liverpool rose from just a small English port to become the prime exporting port for the salt dug in the great Cheshire salt mines and thus became the entrepot for much of the world's salt in the 1800s.
Salt created and destroyed empires. The salt mines of Poland led to a vast kingdom in the 1500s, only to be destroyed when Germans brought in sea salt (to most of the world, considered superior to rock salt). Venice fought and won a war with Genoa over salt. However, Genovites Christopher Columbus and Giovanni Caboto would later destroy the Mediterranean trade by introducing the New World to the market.
Cities, states and duchies along the salt roads exacted heavy duties and taxes for the salt passing through their territories. This practice even caused the formation of cities, such as the city of Munich in 1158, when the then Duke of Bavaria, Henry the Lion, decided that the bishops of Freising no longer needed their salt revenue.
The gabelle — a hated French salt tax — was enacted in 1286 and maintained until 1790. Because of the gabelles, common salt was of such a high value that it caused mass population shifts and exodus, attracted invaders and caused wars.
During more modern times, it became more profitable to sell salted food than pure salt. Thus sources of food to salt went hand in hand with salt making. The British controlled salt works in the Bahamas as well as North American cod fisheries. This may have added to their economic clout during their 19th century imperial expansion period. The search for oil in the late 1800s and early 1900s used the technology and methods pioneered by salt miners, even to the degree that they looked for oil where salt domes were located.