Where does the lore about salt and ghosts originate?

Question

I have watched Supernatural through season seven and always thought the salt thing was particular to the world of "Supernatural." I have not watched or read a lot of "ghost stories."

While watching an episode of Merlin with my daughter today, I saw that they referenced the same idea. In episode 49, A Herald of the New Age, Merlin is tossed a bag of salt with the edict that a ring of it will protect him from evil spirits. The comment is made in jest and Gaius later says the practice is rubbish, but the superstition is referenced.

Upon researching the subject (briefly,) I discovered that some people belive the superstation to be true because salt is supposedly a pure substance, while others believe only blessed salt would work, and others only that salt directly from the sea will work. I did not, However, find anything that suggested an origin for the superstition.

So, what is/are the origins for beliefs that salt will protect against evil spirits? If it is widespread because of various origins, or difficult to know because of its ancient existence, I'd still love to know the countries/regions where the belief seems to have started. Please offer references wherever possible.

Answer 1

There's some interesting info about the history of salt used in superstitions here

The concept of superstitious protection from spirits probably comes from a general understanding of the concept of salt as a preserver of tissues after death.

Wiccanism (and spell-casting in general) certainly has its roots in older pre-christian traditions but it's worth noting that many canons of modern wiccan lore that are portrayed in shows like Merlin and Buffy (including the use of spells, salt rituals, magical arcana, etc) are less than 50-100 years old and that the religion itself is essentially a grab-bag of tenets and rituals from a range of older religions such as early Christianity and Judaism.

Answer 2

In the Philippines, salt is also used against "Manananggal". A (bat?) winged-woman who eats people (and children) who cuts leaves their lower half (waist down) when is out hunting. They say that if you see the woman's lower half, you need to put salt in it to prevent her from returning thus people will find out which lady is the "manananggal".

I thought back then it was a weird belief but after reading a couple of articles where salt was used to fight/prevent creatures...i'm having a whole new respect for salt. Besides making my fried fish more delicious than it already is xD