Do things always look smaller when they are further away? Can something be clearly visible but not there at all? Is it ever possible to have direct and true experience of reality? Are you totally sure?    In this delightful and informative little mathematical history book Phoebe McNaughton takes us on a classical journey through the history of artistic perspective, showing how the eye can be tricked and confused, the brain befuddled, and the philosopher inside all of us awakened by the nature of illusion.    This book about perspective is one of many art books available from the National Gallery, which include art history books, art exhibition catalogues and gift books.