I considered stuff that I could manipulate freely to be a separate thing. This meant that sheets of paper (being glued to the book) were not separate things.

I considered stuff that I could manipulate freely to be a separate thing. This meant that sheets of paper (being glued to the book) were not separate things. I don't recall checking for loose leaves that I stuck in books, though. I wasn't as critical back then as I'm now :) Oh, and the idea breaks down entirely for fluid or gaseous things.