It's rare that film audiences get an opportunity to look deeply into the mind of a filmmaker--yeah, there are the Good Morning America interviews and the DVD audio commentaries, but these are so often characterized by, "Dude, she looked so hot in that dress" kinds of comments.
When Orson Welles was shown Universal's rough cut for his classic Touch of Evil, he promptly wrote out a fiery and detailed 58-page memo filled with proposed changes, all based on his intentions while shooting the film. Although the first theatrical versions of the film did not heed these changes, Welles's wishes were finally honored in a 1996 re-edited version of Touch of Evil.
But the memo, in itself, is worth some attention, for it reveals a precise form of genius, indeed. In the memo, Welles addresses minute details of music (the music from honky-tonk cafes needed to contrast in a jarring fashion), placement of opening credits, editing (many, many specific instances where subtle differences in editing create impressions Welles finds visually and/or aurally unacceptable), dialogue lines, and so much more.
This website--http://www.wellesnet.com/touch_memo1.htm--features an annotated version of the memo, indicating which scenes were changed, how, and when. It's fascinating, but probably only after you've seen the movie a time or two.