In British superstition, a pinch of salt is traditionally thrown over the left shoulder after spilling salt. The gesture is intended to ward off bad luck believed to follow the accident.
Salt was historically valuable and had practical importance as a preservative, so spilling it could be interpreted as wasteful or ominous. In Christian-influenced European folklore, the left side was sometimes associated with the Devil, which helps explain why the corrective gesture is made over the left shoulder. The ritual is symbolic rather than a proven method of changing fortune.
Leonardo da Vinci’s painting The Last Supper is often said to show Judas Iscariot beside an overturned salt cellar, and popular retellings connect this image with the superstition. However, the painting is not a simple documentary record of the custom. Modern versions usually involve only a small pinch of salt, not an entire handful.