A great example about lost work is that the insights we have onto Viking mythology was pretty much documented by a single guy, Snorri Sturluson. What we know ab

A great example about lost work is that the insights we have onto Viking mythology was pretty much documented by a single guy, Snorri Sturluson. What we know about Norse mythology is just a tiny piece of their mythos, as they didn't have the habit of writing down their tales/legends/stories and most of it got lost after they converted to Christianism.