Against a Dwarf (Old English: Wið Dweorh) is an Anglo-Saxon metrical charm found in the Lacnunga. The charm was written in alliterative verse in half lines and was used for its assumed curative properties, although what the charm is supposed to be curing is still a matter of debate.
Some scholars believe that the charm was supposed to help victims sleep more easily if they were suffering from a disease that caused convulsions. Another theory is that the dwarf, a being from Anglo-Saxon mythology, might originally have been a night demon of some kind. The night demon, according to this theory, could possibly have been the personification of the illness.
Most theories that speculate that the dwarf represents some kind of disease usually think that the disease is related to sleeping because of the inclusion of the Seven Sleepers in the charm. According to one source, "The names of the Seven Sleepers of Ephesus occur in various charms of the Middle Ages. They are usually, as might be expected, to secure sleep, but in some cases are to be employed against fever".
Matthew Lewis also believes that the charm is related to helping someone who is having trouble sleeping, and he believes that knowing the origin of the word nightmare is key to understanding the charm. Although the etymology of nightmare is somewhat disputed, the word can possibly be translated as meaning "night monster", specifically a monster that crushes and binds its victims. Sometimes the night monster is thought to sexually abuse its victims. According to Lewis, the dwarf in this charm is a manifestation of a night monster, as dwarfs were linked to the idea of evil spirits and thought to be capable of causing physical harm.