“The book is always better than the movie.” This presumption is widespread, but it is less a critical determination than a personal bias. A movie based on a literary source is often seen as a secondary work and, consequently, of secondary value. Literature, generally, still occupies a more privileged position in the cultural hierarchy than movies do; and readers often have a proprietary attitude toward the book, an attitude that inﬂuences their reception of a ﬁlm based upon it.
Cahir, Linda Costanzo. Literature into Film : Theory and Practical Approaches, McFarland & Company, Incorporated Publishers, 2006.