It must go beyond the form it is using to express ideas beautifully to be literature to me. This at least sets up the possibility of including more than just fiction, or history fictionalized, into the canon. And I do think a canon is important, but I realize that it is also someone's opinion of what should be our canon, and not something set in stone--which is bullshit to large degree. Take my definition of literature for instance, and then also see why I put Watchmen into my canon. One of my bases for including some books is whether or not my favorite writers would be influenced or enjoy the book, and I can easily imagine James Joyce or Thomas Pynchon or Kurt Vonnegut or William Shakespeare reading Watchmen.