" The noun fylgja, formed from the verb "to follow, to accompany" (fylgja), referred in some ways to an individual's double, comparable to the Egyptian Ka and the Greek eidolon. It was a kind of guardian angel that took the form of a female entity (fylgjukona) or an animal that protected the family or person it had adopted. "

― Claude Lecouteux , The Return of the Dead: Ghosts, Ancestors, and the Transparent Veil of the Pagan Mind