In bringing J.R.R. Tolkien's nearly unfilmable work to the screen, Jackson benefited from extraordinary special effects, evocative New Zealand locales, and an exceptionally well-chosen cast, but most of all from his own adaptation with co-writers Fran Walsh and Philippa Boyens, preserving Tolkien's vision and often his very words, but also making logical changes to accommodate the medium of film. While purists complained about these changes and about characters and scenes left out of the films, the additional hours of material in the extended editions help appease them by delving more deeply into Tolkien's music, the characters, and loose ends that enrich the story, such as an explanation of the Faramir-Denethor relationship, and the appearance of the Mouth of Sauron at the gates of Mordor.