The first condition, however, for a fruitful investigation is that we consider the heathen or heathen-appearing records by themselves without mixing their statements with those of Gylfaginning. We must bear in mind that the author of Gylfaginning lived and wrote in the 13th century, more than 200 years after the introduction of Christianity in Iceland, and that his statements accordingly are to be made a link in that chain of documents which exist for the scholar, who tries to follow the fate of the myths during a Christian period and to study their gradual corruption and confusion.
This caution is the more important for the reason that an examination of Gylfaginning very soon shows that the whole cosmographical and eschatological structure which it has built out of fragmentary mythic traditions is based on a conception wholly foreign to Teutonic mythology, that is, on the conception framed by the scholars in Frankish cloisters, and then handed down from chronicle to chronicle, that the Teutons were descended from the Trojans, and that their gods were originally Trojan chiefs and magicians. This "learned" conception found its way to the North and finally developed its most luxurious and abundant blossoms in the Younger Edda preface and in certain other parts of that work.
Permit me to present in brief a sketch of how the cosmography and eschatology of Gylfaginning developed themselves out of this assumption:—The Asas were originally men, and dwelt in the Troy which was situated on the centre of the earth, and which was identical with Asgard (thar næst gerdu their ser borg i midjum heimi, er kallat er Asgardr; that köllum ver Trója; thar bygdu gudin ok ættir theirra ok gjördust thadan af mörg tidindi ok greinir bædi á jord ok á lopti—ch. 9).
The first mythic tradition which supplies material for the structure which Gylfaginning builds on this foundation is the bridge Bifrost. The myth had said that this bridge united the celestial abodes with a part of the universe situated somewhere below. Gylfaginning, which makes the Asas dwell in Troy, therefore makes the gods undertake an enterprise of the greatest boldness, that of building a bridge from Troy to the heavens. But they are extraordinary architects and succeed (Gudin gjördu brú til himins af jördu—ch. 13).
The second mythic tradition employed is Urd's fountain. The myth had stated that the gods daily rode from their celestial abodes on the bridge Bifrost to Urd's (subterranean) fountain. Thence Gylfaginning draws the correct conclusion that Asgard was supposed to be situated at one end of the bridge and Urd's fountain near the other. But from Gylfaginning's premises it follows that if Asgard-Troy is situated on the surface of the earth Urd's fountain must be situated in the heavens, and that the Asas accordingly when they ride to Urd's fountain must ride upward, not downward. The conclusion is drawn with absolute consistency ("Hvern dag rida æsir thangat upp um Bifröst"—ch. 15).
The third mythic tradition used as material is the world-tree, which went (down in the lower world) to Urd's fountain. According to Völuspa (19), this fountain is situated beneath the ash Ygdrasil. The conclusion drawn by Gylfaginning by the aid of its Trojan premises is that since Urd's fountain is situated in the heavens, and still under one of Ygdrasil's roots, this root must be located still further up in the heavens. The placing of the root is also done with consistency, so that we get the following series of wrong localisations:—Down on the earth, Asgard-Troy; thence up to the heavens the bridge Bifrost; above Bifrost, Urd's fountain; high above Urd's fountain, one of Ygdrasil's three roots (which in the mythology are all in the lower world).
Since one of Ygdrasil's roots thus had received its place far up in the heavens, it became necessary to place a second root on a level with the earth, and the third one was allowed to retain its position in the lower world. Thus was produced a just distribution of the roots among the three regions which in the conception of the middle ages constituted the universe, namely, the heavens, the earth, and hell.
In this manner two myths were made to do service in regard to one of the remaining Ygdrasil roots. The one myth was taken from Völuspa, where it was learned that Mimer's fountain is situated below the sacred world-tree; the other was Grimnismal (31), where we are told that frost-giants dwell under one of the three roots. At the time when Gylfaginning was written, and still later, popular traditions told that Gudmund-Mimer was of giant descent (see the middle-age sagas narrated above). From this Gylfaginning draws the conclusion that Mimer was a frost-giant, and it identifies the root which extends to the frost-giants with the root that extends to Mimer's fountain. Thus this fountain of creative power, of world-preservation, of wisdom, and of poetry receives from Gylfaginning its place in the abode of the powers of frost, hostile to gods and to men, in the land of the frost-giants, which Gylfaginning regards as being Jotunheim, bordering on the earth.
In this way Gylfaginning, with the Trojan hypothesis as its starting-point, has gotten so far that it has separated from the lower world with its three realms and three fountains Urd's realm and fountain, they being transferred to the heavens, and Mimer's realm and fountain, they being transferred to Jotunheim. In the mythology these two realms were the subterranean regions of bliss, and the third, Nifelhel, with the regions subject to it, was the abode of the damned. After these separations were made, Gylfaginning, to be logical, had to assume that the lower world of the heathens was exclusively a realm of misery and torture, a sort of counterpart of the hell of the Church. This conclusion is also drawn with due consistency, and Ygdrasil's third root, which in the mythology descended to the well Hvergelmer and to the lower world of the frost-giants, Nifelhel, Nifelheim, extends over the whole lower world, the latter being regarded as identical with Nifelheim and the places of punishment therewith connected.
This result carries with it another. The goddess of the lower world, and particularly of its domain of bliss, was in the mythology, as shall be shown below, the goddess of fate and death, Urd, also called Hel, when named after the country over which she ruled. In a local sense, the name Hel could be applied partly to the whole lower world, which rarely happened, partly to Urd's and Mimer's realms of bliss, which was more common, and Hel was then the opposite of Nifelhel, which was solely the home of misery and torture. Proofs of this shall be given below. But when the lower world had been changed to a sort of hell, the name Hel, both in its local and in its personal sense, must undergo a similar change, and since Urd (the real Hel) was transferred to the heavens, there was nothing to hinder Gylfaginning from substituting for the queen of the lower world Loke's daughter cast down into Nifelhel and giving her the name Hel and the sceptre over the whole lower world.