Hjúki and Bil

Scholarly theories that surround the two concern their nature, their role as potential personifications of the craters on the Moon or its phases, and their relation to later folklore in Germanic Europe.

In chapter 11 of the Prose Edda book Gylfaginning, the enthroned figure of High states that two children by the names of Hjúki and Bil were fathered by Viðfinnr.

"[10] Grimm adds that: Grimm gives further examples from Germanic folklore until the time of his writing (the 19th century) and notes a potential connection between the German word wadel (meaning the full moon) and the dialectal employment of the word for "brushwood, twigs tied up in a bundle, esp[ecially] fir-twigs, wadeln to tie up brushwood", and the practice of cutting wood out in the full moon.

[12] In both the story Hjúki and Bil found in the Icelandic Prose Edda and the English nursery rhyme "Jack and Jill", two children, one male and one female, fetch a pail of water, and the pairs have names that have been perceived as phonetically similar.

Scholar Leander Petzoldt writes that the figure seems to stem from the goddess and over time saw many changes, later developing "an elfin, dwarfish aspect and the ability to cripple people or cattle with the shot of an arrow" (such as in Wolfram von Eschenbach's 13th century poem "Willehalm").

Petzoldt further surveys the development of the figure: During the course of the thirteenth century, the Bilwis is less and less frequently treated as the personification of a supernatural power but becomes increasingly identified as a malevolent human being, a witch.

The Bilwis is one of the strangest and most mysterious beings in all folklore; its varying forms reflect the concerns of a farm culture, and it serves to explain the eerie appearance of turned-down rows of plants in cornfields.