The origins of Beowulf predate the era of readily available manuscripts and texts for a common and, at the time, mostly illiterate peasantry to read.
Though Beowulf was recorded in Old English, it can readily be assumed that its roots are to be found in the mostly oral traditions of the ancient Germanic tribes that roamed and settled much of Western Europe. Because of this heavy oral tradition, stories and legends were passed on by storytellers who would recite their tales from memory. Beowulf, in many ways, reflects this tradition in how it is told. Epics and ballads of considerable length may have needed repetition in order to be memorized easier, and Beowulf has many of its events told again and again. In that sense, a story being retold in Beowulf might be akin to refrain of a song. Also, it is quite possible that the especially more heroic events needed more emphasis, for killing Grendel was no small task, so repetition might have been used as a tool to remind the storytellers as to which events within the Beowulf story were the most important.
In essence, repetition in Beowulf was used both for memorization and event emphasis. First of all, repetition in Beowulf may be present as an aid for memorization. Though there are two different tales of Beowulfs heroism in water, it can be noted that both have many similarities. The first is told at the banquet before Beowulf it to face Grendel. Unferth, king Hrothgars spokesman, notes that Beowulf was bested by one Breca in a swimming contest.
Though Beowulfs response is long and detailed, it is to be seen that he faced more than a few sea monsters. Rough were the waves; fishes in the sea were roused to great anger. Then my coat of mail, hard and hand-linked, guarded me against my enemiesA cruel ravager dragged me down to the sea-bed, a fierce monster held me tightly in its grasp. . .
(42). In his encounter with Grendels mother, much the same is to be seen after Beowulf dives into the lake. Then she grasped at him, clutched the Geat in her ghastly claws; and yet she did not so much as scratch his skin; his coat of mail protected him; she could not penetrate the linked metal rings with her loathsome fingers (61). Though the stories take place at different times and under different circumstances, the parallels can easily be seen.
From this, it can be surmised that for memorization purposes retelling the same story in a different way might be easier than telling a completely new one. Next, and perhaps more importantly, repetition stressed the important events that Beowulf undertook and marked them for the most important parts of the story. This can best be seen in the telling and oft repeated retelling of his encounter with Grendel. The first time it is told, obviously, is when the Geat performs the feat. However, following that, it is told again almost immediately to Hrothgar. I did not hold my deadly enemy firm enough for that; the fiend jerked free with immense power.
Yet, so as to save his life, he left behind his hand (50). Again it is mentioned before Grendels mother attacks the thanes. Grendel, that hateful outcast, was surprised in the hall by a vigilant warrior spoiling for a fight. Grendel gripped and grabbed him there, but the Geat remembered his vast strengththus he overcame the envoy from hell, humbled his evil adversary (57).
Beowulf himself tells of his fight with Grendel to King Hygelac. The demon monster meant to shove me in it, and many another innocent besides; that was beyond him after I leapt up, filled with furyGrendel escapedbut he left behind at Heorot his right hand (73). Though each telling is different in its length and wording, it can be derived that these repetitions are to strike the point home that while Beowulf did go on many different adventures and slay many beasts, the encounters that are repeated are the meat of the story and are the ones that are the most critical to be remembered and repeated.