In The Library of Babel by Jorge Luis Borges, the speaker says,
They were urged on by the delirium of trying to reach the books in the Crimson Hexagon: books whose format is smaller than usual, all-powerful, illustrated and magical.
In the above quote, he mentions the "Crimson Hexagon", which has its own meaning as an almost soul-consuming wish. However, so much of this short story is analogous to and symbolism for real-world objects. So, what does the "crimson hexagon" represent?
A central concern of The Library of Babel — and particularly this section of it — is the search for order and meaning within a chaotic world.
In this passage, Borges introduces the Purifiers; those who, in their pursuit of truth and meaning, destroy anything they consider of no value:
Others, inversely, believed that it was fundamental to eliminate useless works. They invaded the hexagons, showed credentials which were not always false, leafed through a volume with displeasure and condemned whole shelves: their hygienic, ascetic furor caused the senseless perdition of millions of books.
We have already learned enough to understand why this can be considered shocking, blasphemous:
So, the Purifiers are a form of destructive, narrow-minded zealotry. They destroy items of inner beauty, while on a quest that sounds attractive, but upon deeper understanding, is utterly futile.
And now we reach the Crimson Hexagon:
They were urged on by the delirium of trying to reach the books in the Crimson Hexagon: books whose format is smaller than usual, all-powerful, illustrated and magical.
The Crimson Hexagon, mentioned so briefly, is given as the object the Purifiers are seeking. So, we need to understand it as the object that destructive ideologues are after.
In the context of the Library, the Crimson Hexagon sounds utterly out of place. The Library is a place of utter compliance to a constant structure; the Crimson Hexagon is imagined as an utter exception to that, breaking every single rule of the world as we understand it. All the books of the Library have the same characters; those of the Crimson Hexagon break the format and have illustrations. The Crimson Hexagon books are "magical" — a property entirely out of place in our world up until now, where even the most coveted book was prized for the true knowledge it contains, not for any power that is anything other than natural. In every aspect — including their size and appearance — they are other than what the rest of the world contains.
And so, what the Purifiers, the zealots, are seeking is the impossible. They are not content with the world as it is, with its chaos and disorder. They yearn to find, not just greater knowledge and understanding, but all knowledge and power, packed up for them in a way that is entirely outside the realm of reality.
Certainly that is something much to be wished for, but it seems extremely doubtful that any will ever find it.
(An interesting thing to note is that if the Crimson Hexagon is indeed their object, their own methods are a waste of time: the Crimson Hexagon would be easily identifiable; they don't need to destroy every book on all the Hexagons on their way. Futile and destructive.)
This Crimson Hexagon also stands in contrast to the next idea Borges brings: the Man of the Book. This is a much more subtle, and much more plausible, belief - indeed, the Library as describes seems to demand that such a person exist. This is not a belief of total power, breaking the bounds of reality; it is the understanding that reality's shape naturally funnels knowledge to somebody. That a Man of the Book exists somewhere. And, that one's own understanding of that knowledge and that person will be limited.
In conclusion: the Crimson Hexagon is the enticing, but impossible goal, that zealots uses as a hollow drive and justification for their destruction.
