In Norse mythology, Dökkálfar (Old Norse: Døkkálfar "Dark Elves"; singular Døkkálfr) and Ljósálfar (Old Norse for "Light Elves", singular Ljósálfr) are two contrasting types of elves; the former dwell within the earth and are most swarthy, while the latter live in Álfheimr, and are "fairer than the sun to look at". Álfheimr, or Elf-Land, was known as the place of residence for the elves, specifically the light elves. The Dökkálfar and the Ljósálfar are attested in the Prose Edda, written in the 13th century by Snorri Sturluson and in the late Old Norse poem Hrafnagaldr Óðins. Sturluson, born in 1179, was a prominent Icelandic chieftan and poet. Sturluson is known for being a wealthy figure of authority. Snorri was a human paradox. In his work "Snorra Saga Sturlusonar: A Short Biography of Snorri Sturluson," Kevin Wanner explains, "For his own contemporaries Snorri no doubt was the powerful chieftain known for his munificence as well as his avarice…a ruthless intriguer whom it was dangerous to have as one’s adversary. " Scholars have produced theories about the origin and implications of the dualistic concept.