I always disapprove of this sort of literary chauvinism as a matter of principle - GEB is a good book, but hardly necessary to the development of the human organism.
Eh, it's pretty clear that it was only intended to be a hyperbolically strong recommendation of a book. No need to interpret it literally. (Still, despite that, and despite its status as one of my favourite books, I agree that it doesn't really fit as a "rationality quote".)
I always see that the monthly Rationality Quotes thread has this line: "Do not quote comments/posts on LW/OB - if we do this, there should be a separate thread for it." This is the thread for those quotes.
This is a (possibly) monthly thread for posting any interesting rationality-related quotes you've seen on LW/OB.