“Our heathen forefathers,” says Thorlacius[28], “believed, like the Pythagoreans—and the farther back in antiquity the more firmly—that the whole world was filled with spirits of various kinds, to whom they ascribed in general the same nature and properties as the Greeks did to their Dæmons. These were divided into the celestial and the terrestrial, from their places of abode. The former were, according to the ideas of those times, of a good and elevated nature, and of a friendly disposition towards men, whence they also received the name of White or Light Alfs, or spirits. The latter, on the contrary, who were classified after their abodes in the air, sea, and earth, were not regarded in so favourable a light. It was believed that they, particularly the _land ones_, the _δαίμονες ἐπιχθόνιοι_ of the Greeks, constantly and on all occasions sought to torment or injure mankind, and that they had their dwelling partly on the earth in great and thick woods, whence came the name Skovtrolde[29] (Wood-Trolds); or in other desert and lonely places, partly in and under the ground, or in rocks and hills: these last were called Bjerg-Trolde (Hill Trolds); to the first, on account of their different nature, was given the name of Dverge (Dwarfs), and Alve, whence the word Ellefolk, which is still in the Danish language. These Dæmons, particularly the underground ones, were called Svartalfar, that is, Black Spirits, and inasmuch as they did mischief, Trolls.” The prose Edda draws a broad distinction between the light and the black elves,—the former being whiter than the sun; the latter darker than pitch. “Of the origin of the word Alf,” says Mr. Keightley, “nothing satisfactory is to be found. Some think it is akin to the Latin _albus_, white; others to _alpes_, Alps mountains. There is supposed to be some mysterious connection between it and the word Elf or Elv, signifying water in the northern languages; an analogy which has been thought to correspond with that between the Latin Nympha and Lympha. Both relations are perhaps rather fanciful than just. Of the derivation of Alf, as just observed, we know nothing certain[30]; and the original meaning of Nympha would appear to be, a new-married woman[31], and thence a marriageable young woman; and it was applied to the supposed inhabitants of the mountains, seas, and streams, on the same principle that the northern nations gave them the appellation of men and women, that is, from their imagined resemblance to the human form.