The Deathly Hallows (Mark Spoilers!)

[Renmiri]

I think it was to slow down Harry and friends from chasing the Deathly Hallows

I don't really think Dumbledore thought that much in depth about it, because he only really knows of Hermione's level of intellect, and can't really predict what her logical view would be like on such a book. I think he thought that they would notice the emblem, look it up, and then that would be their link to the Deathly Hallows.

But on that scene at King's Cross he did tell Harry that he counted on Hermione to slow them down. That is why I thought the book was his way of making Hermione dismiss it.