I got into a semi-argument with a friend recently regarding how much credit to give George Lucas for Star Wars. She was commenting how he's an awful director and that's why the new Star Wars trilogy was so terrible and I countered Well I've read the script to the original Star Wars and that at least was spectacular, he's a great writer, to which she replied that they had done a major rewrite of his original script for A New Hope because the original script was so bad. Is that true?

And I already know other people wrote the screenplays to The Empire Strikes Back and Return of the Jedi, so now I'm starting to wonder how much of it Lucas himself actually came up with? I want to believe in Lucas but I need to see some evidence!