It's a flat surface, but it appears to have depth, more than than one layer. Are you familiar, with the author, Daniel C. Dennett. I, have one of his books, Freedom Evolves. I'm not quite sure, why I bought it. It's my first book, on philosophy. It, ought to be a hoot, trying to understand it. Sort of like a monkey, who came across, a copy of the Origin of Species.