Neither identified sources nor analogues for Beowulf can be definitively proven, but many conjectures have been made. These are important in helping historians understand the Beowulf manuscript, as possible source-texts or influences would suggest time-frames of composition, geographic boundaries within which it could be composed, or range (both spatial and temporal) of influence (i.e. when it was "popular" and where its "popularity" took it).
There are Scandinavian sources, international folkloric sources, and Celtic sources.[d]
Scandinavian parallels and sources
19th century studies proposed that Beowulf was translated from a lost original Scandinavian work, but this idea was quickly abandoned. But Scandinavian works have continued to be studied as a possible source. Proponents included Gregor Sarrazin writing in 1886 that an Old Norse original version of Beowulf must have existed, but that view was later debunked by Carl Wilhelm von Sydow (1914) who pointed out that Beowulf is fundamentally Christian and written at a time when any Norse tale would have most likely been pagan.
The epic's possible connection to Grettis saga was made early on by Guðbrandur Vigfússon (1878).
Grettis saga is a family saga, and a story about Grettir Ásmundarson, a great-grandson of an Icelandic settler, cannot be comparably as old as Beowulf. Axel Olrik (1903) claimed that on the contrary, this saga was a reworking of Beowulf, and others had followed suit.
However, Friedrich Panzer (1910) wrote a thesis in which both Beowulf and Grettis saga drew from a common folkloric source, and this encouraged even a detractor such W. W. Lawrence to reposition his view, and entertain the possibility that certain elements in the saga (such as the waterfall in place of the mere) retained an older form.
The viability of this connection has enjoyed enduring support, and was characterized as one of the few Scandinavian analogues to receive a general consensus of potential connection by Theodore M. Andersson (1998). But that same year, Magnús Fjalldal published a volume challenging the perception that there is a close parallel, and that tangential similarities were being overemphasized as analogies.
Hrolf kraki and Bodvar Bjarki
Another candidate for a cogener analogue or possible source is the story of Hrolf kraki and his servant, the legendary bear-shapeshifter Bodvar Bjarki. The story survives in Old Norse Hrólfs saga kraka and Saxo's Gesta Danorum. Hrolf kraki, one of the Skjöldungs, even appears as "Hrothulf" in the Anglo-Saxon epic. Hence a story about him and his followers may have developed as early as the 6th century.
International folktale sources
Bear's Son Tale
Friedrich Panzer (1910) wrote a thesis that the first part of Beowulf (the Grendel Story) incorporated preexisting folktale material, and that the folktale in question was of the Bear's Son Tale (Bärensohnmärchen) type, which has surviving examples all over the world.
This tale type was later catalogued as international folktale type 301, now formally entitled "The Three Stolen Princesses" type in Hans Uther's catalogue, although the "Bear's Son" is still used in Beowulf criticism, if not so much in folkloristic circles.
However, although this folkloristic approach was seen as a step in the right direction, "The Bear's Son" tale has later been regarded by many as not a close enough parallel to be a viable choice. Later, Peter Jørgensen, looking for a more concise frame of reference, coined a "two-troll tradition" that covers both Beowulf and Grettis saga: "a Norse 'ecotype' in which a hero enters a cave and kills two giants, usually of different sexes"; which has emerged as a more attractive folk tale parallel, according to a 1998 assessment by Andersson.
Similarity of the epic to the Irish folktale "The Hand and the Child" had already been noted by Albert S. Cook (1899), and others even earlier,[e][f] Swedish folklorist Carl Wilhelm von Sydow (1914) then made a strong argument for the case of parallelism in "The Hand and the Child", because the folktale type demonstrated a "monstrous arm" motif that corresponded with Beowulf wrenching off Grendel's arm. For no such correspondence could be perceived in the Bear's Son Tale or Grettis saga.[g]
James Carney and Martin Puhvel also agree with this "Hand and the Child" contextualisation.[h] Puhvel supported the "Hand and the Child" theory through such motifs as (in Andersson's words) "the more powerful giant mother, the mysterious light in the cave, the melting of the sword in blood, the phenomenon of battle rage, swimming prowess, combat with water monsters, underwater adventures, and the bear-hug style of wrestling."
Attempts to find classical or Late Latin influence or analogue in Beowulf are almost exclusively linked with Homer's Odyssey or Virgil's Aeneid. In 1926, Albert S. Cook suggested a Homeric connection due to equivalent formulas, metonymies, and analogous voyages. In 1930, James A. Work also supported the Homeric influence, stating that encounter between Beowulf and Unferth was parallel to the encounter between Odysseus and Euryalus in Books 7–8 of the Odyssey, even to the point of both characters giving the hero the same gift of a sword upon being proven wrong in their initial assessment of the hero's prowess. This theory of Homer's influence on Beowulf remained very prevalent in the 1920s, but started to die out in the following decade when a handful of critics stated that the two works were merely "comparative literature", although Greek was known in late 7th century England: Bede states that Theodore of Tarsus, a Greek, was appointed Archbishop of Canterbury in 668, and he taught Greek. Several English scholars and churchmen are described by Bede as being fluent in Greek due to being taught by him; Bede claims to be fluent in Greek himself.
Frederick Klaeber, among others, argued for a connection between Beowulf and Virgil near the start of the 20th century, claiming that the very act of writing a secular epic in a Germanic world represents Virgilian influence. Virgil was seen as the pinnacle of Latin literature, and Latin was the dominant literary language of England at the time, therefore making Virgilian influence highly likely. Similarly, in 1971, Alistair Campbell stated that the apologue technique used in Beowulf is so rare in epic poetry aside from Virgil that the poet who composed Beowulf could not have written the poem in such a manner without first coming across Virgil's writings.
It cannot be denied that Biblical parallels occur in the text, whether seen as a pagan work with "Christian colouring" added by scribes or as a "Christian historical novel, with selected bits of paganism deliberately laid on as 'local colour'," as Margaret E. Goldsmith did in "The Christian Theme of Beowulf". Beowulf channels the Book of Genesis, the Book of Exodus, and the Book of Daniel in its inclusion of references to the Genesis creation narrative, the story of Cain and Abel, Noah and the flood, the Devil, Hell, and the Last Judgment.