Why does the poet set up larger cycles of historical and natural time to frame the action of the poem?

Links with Celtic mythology: Another way to view Gawain is to consider its relationship with Celtic mythology, something frequently present in Arthurian material. The Celts, the people who lived in the British Isles prior to the arrival of the Romans and the Anglo-Saxons, had a strong body of pagan belief, ritual practices, and stories surrounding those beliefs and practices. Many of the characters in these myths were gods and goddesses; many of their ritual practices and beliefs echoed motifs in their myths. As the Middle Ages progressed and Christianity grew more dominant, these motifs and characters were often preserved in the folklore and literature of the British Isles. Arthurian material is particularly notable for its ties to Celtic myth, for many of the characters and events in these stories resemble gods and motifs in the older myths. In Gawain, there is a constant sense of the Celtic, pagan cosmology underlying the events with the Green Knight and Gawain's quest. As the poem progresses, this becomes especially complicated when set against the obvious Christianity in the story: Christian belief and pagan ritual mingle in intricate ways in Gawain.