Who wrote down the Norse myths, and can we trust them?

Most of the texts we have on the Norse myths come from Iceland. The oral tradition of the pre-Christian inhabitants was collected and recorded in manuscripts there, primarily in the 13th century. Two works matter most. The Prose Edda, an Old Norse textbook of the early 13th century often attributed to Snorri Sturluson around 1220, is considered the fullest and most detailed source for modern knowledge of Norse mythology. The Poetic Edda is a collection of anonymous poems, passed orally from singer to singer for centuries.

So can we trust them? Partly. Iceland had decided to convert to Christianity in 1000 AD, so the myths were written down by Christians, more than two centuries later. The Prose Edda appears to have been written as a textbook to help poets understand verse and its kennings. Its Prologue gives a Christian twist: the gods become human Trojan warriors who left Troy after its fall. And the surviving manuscripts were all written more than half a century after Snorri's death and differ considerably, so none probably preserves the work exactly as he wrote it.

Snorri himself had a dramatic end. He was assassinated at Reykholt in autumn 1241. Shortly before, he had received a letter in cipher runes warning him of the plot, but he could not understand them.

The Poetic Edda owes its survival to one book: the Codex Regius, thought written in the 1270s and the sole source for most of its poems. It was discovered in 1643, and in 1971 it was brought back to Iceland by ship with a military escort.