the Scefing from squadroned foes
from many a tribe, the mead-bench tore,
awing the earls. Since erst he lay
friendless, a foundling, fate repaid him:
for he waxed under welkin, in wealth he throve,
till before him the folk, both far and near,
who house by the whale-path . . .

Farther down, in the description of Grendel, alliteration appears with the use of "g," "m," and "f."

Grendel this monster grim was called,
march-riever mighty, in moorland living,
in fen and fastness; fief of the giants . . .

One important line comes just after Hrothgar builds his mead hall; this place of feasting and merriment becomes famous, and inflames the passions of the monster Grendel, who is said to be directly descended from Cain.

Then the mighty war-spirit endured for a season,
Bore it bitterly, he who bided in darkness,
That light-hearted laughter loud in the building
Greeted him daily...

Here it is seen how Grendel felt envy for the happiness of the king and warriors. He, as almost a personification of evil and darkness, had to sit and listen to song and laughter for a full year, and so his rage and his eventual attacks are easier to understand.

Another important line comes late in the story; as Beowulf and Wiglaf battle the dragon, Wiglaf gives Beowulf the moral strength to continue:

"Thou wouldst let thine honor not ever be lessened.

Thy life thou shalt save, mighty in actions,
Atheling undaunted, with all of thy vigor;I'll give thee assistance."
(Hall, Beowulf, gutenberg.org)

I have taught Beowulf for years, and I've never run across what I would call the four most famous lines of the epic. However, there are several key points in the story that might have passages worthy of being considered the most important parts of the story. Let's look at the first of these.

The initial focus of the story is Beowulf's quest to kill Grendel. No one has been able to kill this monster. Beowulf brags that he is powerful enough to do it alone and with his bare hands. Not all of the Danes believe he can. Here is what the poet says after Beowulf and Grendel tangle in Herot:

No Dane doubted
The victory, for the proof, hanging high
From the rafters where Beowulf had hung it, was the monster's
Arm, claw and shoulder and all.

This is perhaps the most famous image from the poem; it may be the most famous image in English literature. Beowulf has proved himself to be the warrior he said he was. Now, when he goes on to kill Grendel's mother and eventually, as an old king, the dragon, we are not surprised.