Beowulf, an epic poem composed sometime around the eighth century, tells the story of a hero named Beowulf who travels to Denmark to help rid the Danes of a pair of murdering monsters.
The entire poem juxtaposes the forces of good (the Geat and Danish warriors) against the forces of evil (Grendel, Grendel's mother, and the dragon). As the central figure and epic hero, Beowulf embodies the qualities of good to a greater degree than the other characters.
But what is Beowulf's motivation? Why does he risk everything to help the Danes? That requires a little bit of background information.
Beowulf is not initially present when Grendel begins attacking the Danish warriors at Hrothgar's famed mead hall, Herot. The attacks go on for years, forcing the warriors to abandon the hall.
When Beowulf first arrives at Herot, Hrothgar relates the story of how helped save the life of Beowulf's father, Edgetho, when he was a young man:
Beowulf, you've come to us in friendship, and because
Of the reception you father found at our court.
Edgetho had begun a bitter feud,
Killing Hathlaf, a Wulfing warrior:
Your father's countrymen were afraid of war,
If he returned to his home, and they turned him away.
Then he traveled across the curving waves
To the land of the Danes. I was new to the throne,
Then, a young man ruling this wide
Kingdom and its golden city . . .
I bought the end of Edgetho's
Quarrel, sent ancient treasures through the ocean's
furrows to the Wulfings; your father swore he would keep the peace.
This story shows that Beowulf's motivation in coming to Denmark is to repay the kindness that Hrothgar had shown to his father years before. This selfless act is an indication of “Good,” in the sense that Beowulf didn't have to do it. No one even knew that Beowulf knew of Grendel's terror. When Beowulf, now a symbol of good, shows up at Herot, he clashes with the symbols of “Evil,” Grendel and Grendel's mother, who are said to have descended from Cain.