25 Things You Didn’t Know About Se7en
7. All Of John Doe's Books Were Real… Sort Of
All of John Doe's handwritten notebooks were real books: that is, none of them were blanks.
Every single one was handwritten specifically for the film, although the same text was used for pretty much every page - careful freeze-framing proves this to be the case, and later on when Somerset reads Mills a portion of one of the books, having taken them all off the shelves to catalogue them, he reads from the same page we glimpse earlier on.
However, despite this cost-saving exercise the creation of this monument to monomania took Seven's props department two months to complete, and cost $15,000. Coincidentally, according to Lieutenant Somerset in the movie, it would probably take fifty men reading in shifts two months to read all of the books in the room.
In the same scene he claims that there are 2000 books in evidence with 250 pages per book, but it seems highly unlikely that even a dedicated props department with a perfectionist director would go that far to put together the mise-en-scène required for such a small part of the film.