The origin of Elves (Norse; álfar(elves), álfr(elf)) can be found in ancient Norse mythology, in which, elves are described as divine, or near-divine, race of humanoids (Vættir), likened to the Æsir. In common description they are described as sage and immortal beings occupying the threshold between humans and the gods. In some cases humans that were beloved by the gods became elves within their lives. Ancient Elves are delineated into a pair of similar but distinct races; Light Elves (Ljósálfar) and Dark Elves (Svartálfar), each originating from separate homes within the nine worlds of Yggdrasil. Within the Poetic Edda the differences are commonly ascribed as: "There is one place there that is called the Elf Home (Álfheimr which is the elven city). People live there that are named the light elves (Ljósálfar). But the dark elves (Dökkálfar) live below in earth, in caves and the dark forest and they are unlike them in appearance - and more unlike them in reality. The Light Elves are brighter than the sun in appearance, but the Dark Elves are blacker than pitch." (Snorri, Gylfaginning 17, Prose Edda)