Fafnir his foster-son Sigurd to kill the dragon. Regin instructed Sigurd to dig a pit in which he could lie in wait under the trail Fáfnir used to get to a stream and there plunge his sword, Gram, into Fafnir's heart as he crawls over the pit to the water. Regin then ran away in fear, leaving Sigurd to the task. As Sigurd dug, Odin appeared in the form of an old man with a long beard, advising the warrior to dig more trenches for the blood of Fafnir to run into, presumably so that Sigurd does not drown in the
Investigations into Germanic Mythology there is no explicit revelation in the poem Hárbardsljóð concerning the identity of the title figure, Harbard, who is concealed under this name remained disputed until the end of the 19th century. In the third volume of the same work, Rydberg's theory regarding the World Mill is discussed in relationship to the eddic poem Grottosöngr. He has also been mentioned as one of several writers who proposed analogs for Askr and Embla from comparative mythology, and who sought Indo-Iranian analogs for the Eddic Poem, Völuspá. In 2004, Swedish Doktorand (PhD student) Anna Lindén reviewed the full two-volume work on mythology,