In the only extant note on Sellic Spell, J.R.R. Tolkien wrote:
“This version is a story, not the story. It is only to a limited extent an attempt to reconstruct the Anglo-Saxon tale that lies behind the folk-tale element in Beowulf – in many points it is not possible to do that with certainty; in some points (e.g. the omission of the journey of Grendel’s dam) my tale is not quite the same.
Its principal object is to exhibit the difference of style, tone and atmosphere if the particular heroic or historical is cut out. Of course we do not know what precisely was the style and tone of these lost Old English things. I have given my tale a Northern cast of expression by putting it first into Old English. And by making it timeless I have followed a common habit of folk-tales as received.
As far as Beowulf goes I have attempted to [?draw] a form of story that would have made linking with the Historial Legend easiest – especially in the character of Unfriend. And also a form that will ‘explain’ Handshoe and the disappearance of the companions in the tale as we have it. That the third companion ‘Ashwood’ is in any way related to the coastguard is a mere guess.
The only daughter comes in as a typical folk-tale element. I have associated her with Beowulf. But here the original process was evidently actually more intricate. More than one tale (or motive of tales) was associated with the Danish and Geatish royal houses.”
“Grendel came forth in the dead of night;
the moon in his eyes shone glassy bright,
as over the moors he strode in might,
until he came to Heorot.
Dark lay the dale, the windows shone;
by the wall he lurked and listened long,
and he cursed their laughter and cursed their song
and the twanging harps of Heorot.”