People have long believed in ghosts, and there are many folktales current about them. The same goes for elves and the trolls who are thought to live in crags, hills and mountains. Many believe that it can be dangerous to insult these supernatural beings or creatures (in Icelandic, “verur”).
Special elf-stones can be found widely and it is thought to be risky to tamper with them. As such, there are many examples of plans, such as for roads, which have been altered out of consideration for the elf people. The elves might well avenge any offence, just as many stories relate.