Who is The Author (Paulo Coelho) from Veronika Decides to Die and what is their importance?

Paulo Coelho is a well known author of books that are based upon spiritual illumination and transformation. He makes a rare appearance in "Veronika...," in which he describes the reasons he chose to write the novel. Just as several of the book's characters are transformed by their encounters with Veronika, we can infer that the author has been transformed as well. In essence, the transformations he portrays in his book are, quite possibly, manifestations and projections of his own.