In 1632, Erik Johan Prytz, vicar of Linköping, Sweden, wrote that people would frequently strike deals with nature spirits such as forest nymphs and water spirits in order to learn sorcery, for success in hunting and fishing, and for luck generally (Hall 28).
The evidence, not just from Sweden, but from all over Europe, bears him out.
Swedish sorcerer Matts Larsson was accused in 1685 of having intimate relations with a bergrået, a mountain nymph (Hall 30).
In 1697, the infamous sorcerer Jon of Hallebo confessed that he had received a book of magic from “the man in the stream,” a water spirit known in Swedish as strömkarlen (Hall 32).
The notorious outlaw Tidemann Hemmingsson was also accused of having concluded a pact with a “forest maiden,” a skogsrået, which reportedly granted him good luck in hunting (Hall 35).