The "Encyclopedia of Indo-European Culture" theorizes that Sleipnir's eight legs may be the remnants of horse-associated divine twins found in Indo-European cultures and ultimately stemming from Proto-Indo-European religion. The encyclopedia states that "[...] Sleipnir is born with an extra set of legs, thus representing an original pair of horses. Like Freyr and Njörðr, Sleipnir is responsible for carrying the dead to the otherworld." The encyclopedia cites parallels between the birth of Sleipnir and myths originally pointing to a Celtic goddess who gave birth to the Divine horse twins. These elements include a demand for a goddess by an unwanted suitor (the hrimthurs demanding the goddess Freyja) and the seduction of builders.