“Great scripts are not written, they are rewritten, and rewritten and rewritten” is a statement Robert Downey Jr. made at a Q&A after a screening of Sherlock Holmes at the Director’s Guild of America a while back. He was responding to the question ‘how long in advance do you start memorizing your lines’. He emphatically retorted something to the effect of “why would I memorize lines that I’m not going to say?” and continued on about the process of rewriting a script and how for Holmes lines were still changing the morning before the scene was going to be shot.