Tolkien the Modernist: "Beowulf" and Monsters

From Verlyn Flieger's book Splintered Light:

For all his sympathy with the poet [of Beowulf], he adds the perspective of his own century to his understanding of the Middle Ages in defending the poet's use of monsters as Beowulf's opponents. His reading of the monsters is psychological rather than allegorical. Grendel and the dragon are both monsters, true; but they are not the same kind of monster. In distinguishing between them, Tolkien is a modern, however powerful his inclination toward the past. "In a sense," he says [...] "the foe is always both within and without.... Thus Grendel has a perverted human shape.... For it is true of man, maker of myths, that Grendel and the Dragon, in their lust, greed, and malice, have a part in him." The monsters are within us as well as outside us. The hostile dark is a part of man, not just his besieging foe. The dragon may be the instrument of final defeat, but Grendel carries his own threat to humanity, for he moves in the shape of a man. And though the youthful Beowulf is victorious in his meeting with Grendel, that inner darkness, no less than the dragon's external threat, is always there to be battled.

The recurrence of these references to darkness, to the precariousness of the light, to the monsters, is forceful evidence of the emotional pull of the dark for Tolkien. His own reading of Christianity tends to emphasize the tragedy of the Fall and its consequences. [...] Tolkien's ability to enter in to the mood and spirit of Beowulf is persuasive evidence that he was acquainted firsthand with the battle [against the dark] and that, as Humphrey Carpenter comments, his experience had taught him that "no battle would be won forever." He could not have seen so deeply into the poem or experienced such near-identification with the poet unless Beowulf had struck a sympathetic chord in his own nature. It would seem clear that however he may qualify the pagan point of view, his heart is with the tragedy.