The principle superstition existing about salt is that spilling it at the table is considered a bad omen: But ill-luck can be averted, say the superstitious, if a pinch of the spilled salt is thrown with the right hand over the left shoulder.
It is not true that this superstition comes from the belief that Jesus, at the Last Supper, upset a salt-celler. The only instance of this story is contained in a painting of the Last Supper by Leonardo da Vinci.
In fact, the spilling of salt was taken as an ill-omen by the Romans long before the time of Jesus.
Salt was used in early Biblical times by the Jews in their sacrifices. As an emblem of preservation, it was ordered by Moses to be strewn over all flesh that was to be used in sacrifices.
Grose, commenting on the spilt salt in his Antiquities (1731) says that it is unlucky to help people to salt. The spilling of salt is also mentioned by Scot in his Discovery of Witchcraft (1684) and by Gaul in Maq-Astro -Mancers.
Both the Greeks and Romans mixed salt in their sacrificial cakes and in their lustrations (purification ceremonies) made use of salt and water which, says Pennant, gave rise to the practice of the use of the Holy Water by the church. It was the custom in Northumberland in England to set a pewter plate containing a little salt upon a corpse. It is still not uncommon to put salt into a coffin.
Salt was a highly prized commodity in Biblical times. It is referred to repeatedly in the Bible, one instance being “If he be not worth his salt.”