I had been obsessed with the Arthurian legends all my life, and I knew that that would work its way into any trilogy I wrote. I was fascinated by the Eddas, the Norse and Icelandic legends, Odin on the world tree.
It's worth being suspicious of writers - or anyone! - who does that myth-making thing. There's always a tendency to retrospectively impose structures on a life. Life as it's lived has a far more complex shape.