Learned: Fairy Tale Exposition

In the preface of C.S. Lewis' That Hideous Strength, Lewis points out that the fairy tales of all all begin with mundane beginnings. The culture and villages described in old fairy tale seems quaint and magical to us, but when they were originally written and told, the beginnings always described life as it truly was and then introduced magical elements. I thought it a very astute observation, and I wonder how it should affect my own writing.